package org.hl7.fhir.r5.conformance;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;

/*
  Copyright (c) 2011+, HL7, Inc.
  All rights reserved.
  
  Redistribution and use in source and binary forms, with or without modification, 
  are permitted provided that the following conditions are met:
    
   * Redistributions of source code must retain the above copyright notice, this 
     list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above copyright notice, 
     this list of conditions and the following disclaimer in the documentation 
     and/or other materials provided with the distribution.
   * Neither the name of HL7 nor the names of its contributors may be used to 
     endorse or promote products derived from this software without specific 
     prior written permission.
  
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
  POSSIBILITY OF SUCH DAMAGE.
  
 */


import java.io.IOException;
import java.io.OutputStream;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.lang3.StringUtils;
import org.hl7.fhir.exceptions.DefinitionException;
import org.hl7.fhir.exceptions.FHIRException;
import org.hl7.fhir.exceptions.FHIRFormatError;
import org.hl7.fhir.r5.conformance.ProfileUtilities.ProfileKnowledgeProvider.BindingResolution;
import org.hl7.fhir.r5.context.IWorkerContext;
import org.hl7.fhir.r5.context.IWorkerContext.ValidationResult;
import org.hl7.fhir.r5.elementmodel.ObjectConverter;
import org.hl7.fhir.r5.elementmodel.Property;
import org.hl7.fhir.r5.formats.IParser;
import org.hl7.fhir.r5.model.Base;
import org.hl7.fhir.r5.model.BooleanType;
import org.hl7.fhir.r5.model.CanonicalType;
import org.hl7.fhir.r5.model.CodeType;
import org.hl7.fhir.r5.model.CodeableConcept;
import org.hl7.fhir.r5.model.Coding;
import org.hl7.fhir.r5.model.DataType;
import org.hl7.fhir.r5.model.Element;
import org.hl7.fhir.r5.model.ElementDefinition;
import org.hl7.fhir.r5.model.ElementDefinition.AggregationMode;
import org.hl7.fhir.r5.model.ElementDefinition.DiscriminatorType;
import org.hl7.fhir.r5.model.ElementDefinition.ElementDefinitionBaseComponent;
import org.hl7.fhir.r5.model.ElementDefinition.ElementDefinitionBindingComponent;
import org.hl7.fhir.r5.model.ElementDefinition.ElementDefinitionConstraintComponent;
import org.hl7.fhir.r5.model.ElementDefinition.ElementDefinitionExampleComponent;
import org.hl7.fhir.r5.model.ElementDefinition.ElementDefinitionMappingComponent;
import org.hl7.fhir.r5.model.ElementDefinition.ElementDefinitionSlicingComponent;
import org.hl7.fhir.r5.model.ElementDefinition.ElementDefinitionSlicingDiscriminatorComponent;
import org.hl7.fhir.r5.model.ElementDefinition.PropertyRepresentation;
import org.hl7.fhir.r5.model.ElementDefinition.SlicingRules;
import org.hl7.fhir.r5.model.ElementDefinition.TypeRefComponent;
import org.hl7.fhir.r5.model.Enumeration;
import org.hl7.fhir.r5.model.Enumerations.BindingStrength;
import org.hl7.fhir.r5.model.Enumerations.FHIRVersion;
import org.hl7.fhir.r5.model.Enumerations.PublicationStatus;
import org.hl7.fhir.r5.model.ExpressionNode;
import org.hl7.fhir.r5.model.ExpressionNode.Kind;
import org.hl7.fhir.r5.model.ExpressionNode.Operation;
import org.hl7.fhir.r5.model.Extension;
import org.hl7.fhir.r5.model.IdType;
import org.hl7.fhir.r5.model.IntegerType;
import org.hl7.fhir.r5.model.PrimitiveType;
import org.hl7.fhir.r5.model.Quantity;
import org.hl7.fhir.r5.model.Resource;
import org.hl7.fhir.r5.model.StringType;
import org.hl7.fhir.r5.model.StructureDefinition;
import org.hl7.fhir.r5.model.StructureDefinition.ExtensionContextType;
import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionContextComponent;
import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionDifferentialComponent;
import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionKind;
import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionMappingComponent;
import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionSnapshotComponent;
import org.hl7.fhir.r5.model.StructureDefinition.TypeDerivationRule;
import org.hl7.fhir.r5.model.UriType;
import org.hl7.fhir.r5.model.UsageContext;
import org.hl7.fhir.r5.model.ValueSet;
import org.hl7.fhir.r5.model.ValueSet.ValueSetExpansionComponent;
import org.hl7.fhir.r5.model.ValueSet.ValueSetExpansionContainsComponent;
import org.hl7.fhir.r5.renderers.TerminologyRenderer;
import org.hl7.fhir.r5.renderers.spreadsheets.SpreadsheetGenerator;
import org.hl7.fhir.r5.terminologies.ValueSetExpander.ValueSetExpansionOutcome;
import org.hl7.fhir.r5.utils.FHIRLexer;
import org.hl7.fhir.r5.utils.FHIRPathEngine;
import org.hl7.fhir.r5.utils.PublicationHacker;
import org.hl7.fhir.r5.utils.ToolingExtensions;
import org.hl7.fhir.r5.utils.TranslatingUtilities;
import org.hl7.fhir.r5.utils.XVerExtensionManager;
import org.hl7.fhir.r5.utils.XVerExtensionManager.XVerExtensionStatus;
import org.hl7.fhir.r5.utils.formats.CSVWriter;
import org.hl7.fhir.utilities.CommaSeparatedStringBuilder;
import org.hl7.fhir.utilities.MarkDownProcessor;
import org.hl7.fhir.utilities.Utilities;
import org.hl7.fhir.utilities.VersionUtilities;
import org.hl7.fhir.utilities.i18n.I18nConstants;
import org.hl7.fhir.utilities.validation.ValidationMessage;
import org.hl7.fhir.utilities.validation.ValidationMessage.IssueSeverity;
import org.hl7.fhir.utilities.validation.ValidationMessage.IssueType;
import org.hl7.fhir.utilities.validation.ValidationMessage.Source;
import org.hl7.fhir.utilities.validation.ValidationOptions;
import org.hl7.fhir.utilities.xhtml.HierarchicalTableGenerator;
import org.hl7.fhir.utilities.xhtml.HierarchicalTableGenerator.Cell;
import org.hl7.fhir.utilities.xhtml.HierarchicalTableGenerator.Piece;
import org.hl7.fhir.utilities.xhtml.HierarchicalTableGenerator.Row;
import org.hl7.fhir.utilities.xhtml.HierarchicalTableGenerator.TableModel;
import org.hl7.fhir.utilities.xhtml.XhtmlNode;
import org.hl7.fhir.utilities.xml.SchematronWriter;
import org.hl7.fhir.utilities.xml.SchematronWriter.Rule;
import org.hl7.fhir.utilities.xml.SchematronWriter.SchematronType;
import org.hl7.fhir.utilities.xml.SchematronWriter.Section;

/** 
 * This class provides a set of utility operations for working with Profiles.
 * Key functionality:
 *  * getChildMap --?
 *  * getChildList
 *  * generateSnapshot: Given a base (snapshot) profile structure, and a differential profile, generate a new snapshot profile
 *  * closeDifferential: fill out a differential by excluding anything not mentioned
 *  * generateExtensionsTable: generate the HTML for a hierarchical table presentation of the extensions
 *  * generateTable: generate  the HTML for a hierarchical table presentation of a structure
 *  * generateSpanningTable: generate the HTML for a table presentation of a network of structures, starting at a nominated point
 *  * summarize: describe the contents of a profile
 *  
 * note to maintainers: Do not make modifications to the snapshot generation without first changing the snapshot generation test cases to demonstrate the grounds for your change
 *  
 * @author Grahame
 *
 */
public class ProfileUtilities extends TranslatingUtilities {

  public class ElementDefinitionResolution {

    private StructureDefinition source;
    private ElementDefinition element;

    public ElementDefinitionResolution(StructureDefinition source, ElementDefinition element) {
      this.source = source;
      this.element = element;
    }

    public StructureDefinition getSource() {
      return source;
    }

    public ElementDefinition getElement() {
      return element;
    }

  }

  public class ElementRedirection {

    private String path;
    private ElementDefinition element;

    public ElementRedirection(ElementDefinition element, String path) {
      this.path = path;
      this.element = element;
    }

    public ElementDefinition getElement() {
      return element;
    }

    @Override
    public String toString() {
      return element.toString() + " : "+path;
    }

    public String getPath() {
      return path;
    }

  }
  
  public class TypeSlice {
    private ElementDefinition defn;
    private String type;
    public TypeSlice(ElementDefinition defn, String type) {
      super();
      this.defn = defn;
      this.type = type;
    }
    public ElementDefinition getDefn() {
      return defn;
    }
    public String getType() {
      return type;
    }
    
  }
  public class BaseTypeSlice {
    private ElementDefinition defn;
    private String type;
    private int start;
    private int end;
    public boolean handled;
    public BaseTypeSlice(ElementDefinition defn, String type, int start, int end) {
      super();
      this.defn = defn;
      this.type = type;
      this.start = start;
      this.end = end;
    }
  }

  public static class ElementChoiceGroup {
    private Row row;
    private String name;
    private boolean mandatory;
    private List<String> elements = new ArrayList<>();
    
    public ElementChoiceGroup(String name, boolean mandatory) {
      super();
      this.name = name;
      this.mandatory = mandatory;
    }
    public Row getRow() {
      return row;
    }
    public List<String> getElements() {
      return elements;
    }
    public void setRow(Row row) {
      this.row = row;      
    }
    public String getName() {
      return name;
    }
  }
  
  private static final int MAX_RECURSION_LIMIT = 10;
  
  public class ExtensionContext {

    private ElementDefinition element;
    private StructureDefinition defn;

    public ExtensionContext(StructureDefinition ext, ElementDefinition ed) {
      this.defn = ext;
      this.element = ed;
    }

    public ElementDefinition getElement() {
      return element;
    }

    public StructureDefinition getDefn() {
      return defn;
    }

    public String getUrl() {
      if (element == defn.getSnapshot().getElement().get(0))
        return defn.getUrl();
      else
        return element.getSliceName();
    }

    public ElementDefinition getExtensionValueDefinition() {
      int i = defn.getSnapshot().getElement().indexOf(element)+1;
      while (i < defn.getSnapshot().getElement().size()) {
        ElementDefinition ed = defn.getSnapshot().getElement().get(i);
        if (ed.getPath().equals(element.getPath()))
          return null;
        if (ed.getPath().startsWith(element.getPath()+".value") && !ed.hasSlicing())
          return ed;
        i++;
      }
      return null;
    }
  }

  private static final String ROW_COLOR_ERROR = "#ffcccc";
  private static final String ROW_COLOR_FATAL = "#ff9999";
  private static final String ROW_COLOR_WARNING = "#ffebcc";
  private static final String ROW_COLOR_HINT = "#ebf5ff";
  private static final String ROW_COLOR_NOT_MUST_SUPPORT = "#d6eaf8";
  public static final int STATUS_OK = 0;
  public static final int STATUS_HINT = 1;
  public static final int STATUS_WARNING = 2;
  public static final int STATUS_ERROR = 3;
  public static final int STATUS_FATAL = 4;


  private static final String DERIVATION_EQUALS = "derivation.equals";
  public static final String DERIVATION_POINTER = "derived.pointer";
  public static final String IS_DERIVED = "derived.fact";
  public static final String UD_ERROR_STATUS = "error-status";
  private static final String GENERATED_IN_SNAPSHOT = "profileutilities.snapshot.processed";
  private static final boolean COPY_BINDING_EXTENSIONS = false;
  private static final boolean DONT_DO_THIS = false;
  private final boolean ADD_REFERENCE_TO_TABLE = true;

  private boolean useTableForFixedValues = true;
  private boolean debug;

  // note that ProfileUtilities are used re-entrantly internally, so nothing with process state can be here
  private final IWorkerContext context;
  private FHIRPathEngine fpe;
  private List<ValidationMessage> messages;
  private List<String> snapshotStack = new ArrayList<String>();
  private ProfileKnowledgeProvider pkp;
  private boolean igmode;
  private boolean exception;
  private ValidationOptions terminologyServiceOptions = new ValidationOptions();
  private boolean newSlicingProcessing;
  private String defWebRoot;
  private boolean autoFixSliceNames;
  private XVerExtensionManager xver;
  private boolean wantFixDifferentialFirstElementType;
  private Set<String> masterSourceFileNames;

  public ProfileUtilities(IWorkerContext context, List<ValidationMessage> messages, ProfileKnowledgeProvider pkp, FHIRPathEngine fpe) {
    super();
    this.context = context;
    this.messages = messages;
    this.pkp = pkp;

    this.fpe = fpe;
    if (context != null && this.fpe == null) {
      this.fpe = new FHIRPathEngine(context, this);
    }
  }

  public ProfileUtilities(IWorkerContext context, List<ValidationMessage> messages, ProfileKnowledgeProvider pkp) {
    super();
    this.context = context;
    this.messages = messages;
    this.pkp = pkp;
    if (context != null) {
      this.fpe = new FHIRPathEngine(context, this);
    }
  }
  
  public static class UnusedTracker {
    private boolean used;
  }

  public boolean isIgmode() {
    return igmode;
  }

  public void setIgmode(boolean igmode) {
    this.igmode = igmode;
  }
  
  public boolean isWantFixDifferentialFirstElementType() {
    return wantFixDifferentialFirstElementType;
  }

  public void setWantFixDifferentialFirstElementType(boolean wantFixDifferentialFirstElementType) {
    this.wantFixDifferentialFirstElementType = wantFixDifferentialFirstElementType;
  }

  public boolean isAutoFixSliceNames() {
    return autoFixSliceNames;
  }

  public ProfileUtilities setAutoFixSliceNames(boolean autoFixSliceNames) {
    this.autoFixSliceNames = autoFixSliceNames;
    return this;
  }

  public interface ProfileKnowledgeProvider {
    class BindingResolution {
      public String display;
      public String url;
    }
    boolean isDatatype(String typeSimple);
    boolean isResource(String typeSimple);
    boolean hasLinkFor(String typeSimple);
    String getLinkFor(String corePath, String typeSimple);
    BindingResolution resolveBinding(StructureDefinition def,
      ElementDefinitionBindingComponent binding, String path) throws FHIRException;
    BindingResolution resolveBinding(StructureDefinition def, String url, String path) throws FHIRException;
    String getLinkForProfile(StructureDefinition profile, String url);
    boolean prependLinks();
    String getLinkForUrl(String corePath, String s);
  }



  public List<ElementDefinition> getChildMap(StructureDefinition profile, ElementDefinition element) throws DefinitionException {
    if (element.getContentReference() != null) {
      List<ElementDefinition> list = null;
      String id = null;
      if (element.getContentReference().startsWith("#")) {
        // internal reference
        id = element.getContentReference().substring(1);
        list = profile.getSnapshot().getElement();
      } else if (element.getContentReference().contains("#")) {
        // external reference
        String ref = element.getContentReference();
        StructureDefinition sd = context.fetchResource(StructureDefinition.class, ref.substring(0, ref.indexOf("#")));
        if (sd == null) {
          throw new DefinitionException("unable to process contentReference '"+element.getContentReference()+"' on element '"+element.getId()+"'");
        }
        list = sd.getSnapshot().getElement();
        id = ref.substring(ref.indexOf("#")+1);        
      } else {
        throw new DefinitionException("unable to process contentReference '"+element.getContentReference()+"' on element '"+element.getId()+"'");
      }
        
      for (ElementDefinition e : list) {
        if (id.equals(e.getId()))
          return getChildMap(profile, e);
      }
      throw new DefinitionException(context.formatMessage(I18nConstants.UNABLE_TO_RESOLVE_NAME_REFERENCE__AT_PATH_, element.getContentReference(), element.getPath()));

    } else {
      List<ElementDefinition> res = new ArrayList<ElementDefinition>();
      List<ElementDefinition> elements = profile.getSnapshot().getElement();
      String path = element.getPath();
      for (int index = elements.indexOf(element) + 1; index < elements.size(); index++) {
        ElementDefinition e = elements.get(index);
        if (e.getPath().startsWith(path + ".")) {
          // We only want direct children, not all descendants
          if (!e.getPath().substring(path.length()+1).contains("."))
            res.add(e);
        } else
          break;
      }
      return res;
    }
  }


  public List<ElementDefinition> getSliceList(StructureDefinition profile, ElementDefinition element) throws DefinitionException {
    if (!element.hasSlicing())
      throw new Error(context.formatMessage(I18nConstants.GETSLICELIST_SHOULD_ONLY_BE_CALLED_WHEN_THE_ELEMENT_HAS_SLICING));

    List<ElementDefinition> res = new ArrayList<ElementDefinition>();
    List<ElementDefinition> elements = profile.getSnapshot().getElement();
    String path = element.getPath();
    for (int index = elements.indexOf(element) + 1; index < elements.size(); index++) {
      ElementDefinition e = elements.get(index);
      if (e.getPath().startsWith(path + ".") || e.getPath().equals(path)) {
        // We want elements with the same path (until we hit an element that doesn't start with the same path)
        if (e.getPath().equals(element.getPath()))
          res.add(e);
      } else
        break;
    }
    return res;
  }


  /**
   * Given a Structure, navigate to the element given by the path and return the direct children of that element
   *
   * @param structure The structure to navigate into
   * @param path The path of the element within the structure to get the children for
   * @return A List containing the element children (all of them are Elements)
   */
  public List<ElementDefinition> getChildList(StructureDefinition profile, String path, String id) {
    return getChildList(profile, path, id, false);
  }
  
  public List<ElementDefinition> getChildList(StructureDefinition profile, String path, String id, boolean diff) {
    return getChildList(profile, path, id, diff, false);
  }
  
  public List<ElementDefinition> getChildList(StructureDefinition profile, String path, String id, boolean diff, boolean refs) {
    List<ElementDefinition> res = new ArrayList<ElementDefinition>();

    boolean capturing = id==null;
    if (id==null && !path.contains("."))
      capturing = true;
  
    List<ElementDefinition> list = diff ? profile.getDifferential().getElement() : profile.getSnapshot().getElement();
    for (ElementDefinition e : list) {
      if (e == null)
        throw new Error(context.formatMessage(I18nConstants.ELEMENT__NULL_, profile.getUrl()));
      if (e.getId() == null)
        throw new Error(context.formatMessage(I18nConstants.ELEMENT_ID__NULL__ON_, e.toString(), profile.getUrl()));
      
      if (!capturing && id!=null && e.getId().equals(id)) {
        capturing = true;
      }
      
      // If our element is a slice, stop capturing children as soon as we see the next slice
      if (capturing && e.hasId() && id!= null && !e.getId().equals(id) && e.getPath().equals(path))
        break;
      
      if (capturing) {
        String p = e.getPath();
  
        if (refs && !Utilities.noString(e.getContentReference()) && path.startsWith(p)) {
          if (path.length() > p.length()) {
            return getChildList(profile, e.getContentReference()+"."+path.substring(p.length()+1), null, diff);
          } else if (e.getContentReference().startsWith("#")) {
            return getChildList(profile, e.getContentReference().substring(1), null, diff);            
          } else if (e.getContentReference().contains("#")) {
            String url = e.getContentReference().substring(0, e.getContentReference().indexOf("#"));
            StructureDefinition sd = context.fetchResource(StructureDefinition.class, url);
            if (sd == null) {
              throw new DefinitionException("Unable to find Structure "+url);
            }
            return getChildList(sd, e.getContentReference().substring(e.getContentReference().indexOf("#")+1), null, diff);            
          } else {
            return getChildList(profile, e.getContentReference(), null, diff);
          }
          
        } else if (p.startsWith(path+".") && !p.equals(path)) {
          String tail = p.substring(path.length()+1);
          if (!tail.contains(".")) {
            res.add(e);
          }
        }
      }
    }

    return res;
  }

  public List<ElementDefinition> getChildList(StructureDefinition structure, ElementDefinition element, boolean diff, boolean refs) {
    return getChildList(structure, element.getPath(), element.getId(), diff, refs);
  }

  public List<ElementDefinition> getChildList(StructureDefinition structure, ElementDefinition element, boolean diff) {
    return getChildList(structure, element.getPath(), element.getId(), diff);
  }

  public List<ElementDefinition> getChildList(StructureDefinition structure, ElementDefinition element) {
    if (element.hasContentReference()) {
      ElementDefinition target = element;
      for (ElementDefinition t : structure.getSnapshot().getElement()) {
        if (t.getId().equals(element.getContentReference().substring(1))) {
          target = t;
        }
      }      
      return getChildList(structure, target.getPath(), target.getId(), false);
    } else {
      return getChildList(structure, element.getPath(), element.getId(), false);
    }
        }

  public void updateMaps(StructureDefinition base, StructureDefinition derived) throws DefinitionException {
    if (base == null)
      throw new DefinitionException(context.formatMessage(I18nConstants.NO_BASE_PROFILE_PROVIDED));
    if (derived == null)
      throw new DefinitionException(context.formatMessage(I18nConstants.NO_DERIVED_STRUCTURE_PROVIDED));
    
    for (StructureDefinitionMappingComponent baseMap : base.getMapping()) {
      boolean found = false;
      for (StructureDefinitionMappingComponent derivedMap : derived.getMapping()) {
        if (derivedMap.getUri() != null && derivedMap.getUri().equals(baseMap.getUri())) {
          found = true;
          break;
        }
      }
      if (!found) {
        derived.getMapping().add(baseMap);
      }
    }
  }
  
  /**
   * Given a base (snapshot) profile structure, and a differential profile, generate a new snapshot profile
   *
   * @param base - the base structure on which the differential will be applied
   * @param differential - the differential to apply to the base
   * @param url - where the base has relative urls for profile references, these need to be converted to absolutes by prepending this URL (e.g. the canonical URL)
   * @param webUrl - where the base has relative urls in markdown, these need to be converted to absolutes by prepending this URL (this is not the same as the canonical URL)
   * @param trimDifferential - if this is true, then the snap short generator will remove any material in the element definitions that is not different to the base
   * @return
   * @throws FHIRException 
   * @throws DefinitionException 
   * @throws Exception
   */
  public void generateSnapshot(StructureDefinition base, StructureDefinition derived, String url, String webUrl, String profileName) throws DefinitionException, FHIRException {
    if (base == null) {
      throw new DefinitionException(context.formatMessage(I18nConstants.NO_BASE_PROFILE_PROVIDED));
    }
    if (derived == null) {
      throw new DefinitionException(context.formatMessage(I18nConstants.NO_DERIVED_STRUCTURE_PROVIDED));
    }
    checkNotGenerating(base, "Base for generating a snapshot for the profile "+derived.getUrl());
    checkNotGenerating(derived, "Focus for generating a snapshot");

    if (!base.hasType()) {
      throw new DefinitionException(context.formatMessage(I18nConstants.BASE_PROFILE__HAS_NO_TYPE, base.getUrl()));
    }
    if (!derived.hasType()) {
      throw new DefinitionException(context.formatMessage(I18nConstants.DERIVED_PROFILE__HAS_NO_TYPE, derived.getUrl()));
    }
    if (!derived.hasDerivation()) {
      throw new DefinitionException(context.formatMessage(I18nConstants.DERIVED_PROFILE__HAS_NO_DERIVATION_VALUE_AND_SO_CANT_BE_PROCESSED, derived.getUrl()));
    }
    if (!base.getType().equals(derived.getType()) && derived.getDerivation() == TypeDerivationRule.CONSTRAINT) {
      throw new DefinitionException(context.formatMessage(I18nConstants.BASE__DERIVED_PROFILES_HAVE_DIFFERENT_TYPES____VS___, base.getUrl(), base.getType(), derived.getUrl(), derived.getType()));
    }
    
    if (snapshotStack.contains(derived.getUrl())) {
      throw new DefinitionException(context.formatMessage(I18nConstants.CIRCULAR_SNAPSHOT_REFERENCES_DETECTED_CANNOT_GENERATE_SNAPSHOT_STACK__, snapshotStack.toString()));
    }
    derived.setUserData("profileutils.snapshot.generating", true);
    snapshotStack.add(derived.getUrl());

    if (!Utilities.noString(webUrl) && !webUrl.endsWith("/"))
      webUrl = webUrl + '/';

    if (defWebRoot == null)
      defWebRoot = webUrl;
    derived.setSnapshot(new StructureDefinitionSnapshotComponent());

    try {
      checkDifferential(derived.getDifferential().getElement(), typeName(derived.getType()), derived.getUrl());
      checkDifferentialBaseType(derived);
      
      // so we have two lists - the base list, and the differential list
      // the differential list is only allowed to include things that are in the base list, but
      // is allowed to include them multiple times - thereby slicing them

      // our approach is to walk through the base list, and see whether the differential
      // says anything about them.
      int baseCursor = 0;
      int diffCursor = 0; // we need a diff cursor because we can only look ahead, in the bound scoped by longer paths


      for (ElementDefinition e : derived.getDifferential().getElement()) 
        e.clearUserData(GENERATED_IN_SNAPSHOT);

      // we actually delegate the work to a subroutine so we can re-enter it with a different cursors
      StructureDefinitionDifferentialComponent diff = cloneDiff(derived.getDifferential()); // we make a copy here because we're sometimes going to hack the differential while processing it. Have to migrate user data back afterwards
      StructureDefinitionSnapshotComponent baseSnapshot  = base.getSnapshot(); 
      if (derived.getDerivation() == TypeDerivationRule.SPECIALIZATION) {
        String derivedType = derived.getType();
        if (StructureDefinitionKind.LOGICAL.equals(derived.getKind()) && derived.getType().contains("/")) {
          derivedType = derivedType.substring(derivedType.lastIndexOf("/")+1);
        }
        baseSnapshot = cloneSnapshot(baseSnapshot, base.getType(), derivedType);
      }
//      if (derived.getId().equals("2.16.840.1.113883.10.20.22.2.1.1")) {
//        debug = true;
//      }
      processPaths("", derived.getSnapshot(), baseSnapshot, diff, baseCursor, diffCursor, baseSnapshot.getElement().size()-1, 
          derived.getDifferential().hasElement() ? derived.getDifferential().getElement().size()-1 : -1, url, webUrl, derived.present(), null, null, false, base.getUrl(), null, false, null, null, new ArrayList<ElementRedirection>(), base);
      checkGroupConstraints(derived);
      if (derived.getDerivation() == TypeDerivationRule.SPECIALIZATION) {
        for (ElementDefinition e : diff.getElement()) {
          if (!e.hasUserData(GENERATED_IN_SNAPSHOT)) {
            ElementDefinition outcome = updateURLs(url, webUrl, e.copy());
            e.setUserData(GENERATED_IN_SNAPSHOT, outcome);
            derived.getSnapshot().addElement(outcome);
          }
        }
      }
      
      if (derived.getKind() != StructureDefinitionKind.LOGICAL && !derived.getSnapshot().getElementFirstRep().getType().isEmpty())
        throw new Error(context.formatMessage(I18nConstants.TYPE_ON_FIRST_SNAPSHOT_ELEMENT_FOR__IN__FROM_, derived.getSnapshot().getElementFirstRep().getPath(), derived.getUrl(), base.getUrl()));
      updateMaps(base, derived);

      setIds(derived, false);
      if (debug) {
        System.out.println("Differential: ");
        for (ElementDefinition ed : derived.getDifferential().getElement())
          System.out.println("  "+ed.getId()+" : "+typeSummaryWithProfile(ed)+"["+ed.getMin()+".."+ed.getMax()+"]"+sliceSummary(ed)+"  "+constraintSummary(ed));
        System.out.println("Snapshot: ");
        for (ElementDefinition ed : derived.getSnapshot().getElement())
          System.out.println("  "+ed.getId()+" : "+typeSummaryWithProfile(ed)+"["+ed.getMin()+".."+ed.getMax()+"]"+sliceSummary(ed)+"  "+constraintSummary(ed));
      }
      CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder();
      //Check that all differential elements have a corresponding snapshot element
      int ce = 0;
      for (ElementDefinition e : diff.getElement()) {
        if (!e.hasUserData("diff-source"))
          throw new Error(context.formatMessage(I18nConstants.UNXPECTED_INTERNAL_CONDITION__NO_SOURCE_ON_DIFF_ELEMENT));
        else {
          if (e.hasUserData(DERIVATION_EQUALS))
            ((Base) e.getUserData("diff-source")).setUserData(DERIVATION_EQUALS, e.getUserData(DERIVATION_EQUALS));
          if (e.hasUserData(DERIVATION_POINTER))
            ((Base) e.getUserData("diff-source")).setUserData(DERIVATION_POINTER, e.getUserData(DERIVATION_POINTER));
        }
        if (!e.hasUserData(GENERATED_IN_SNAPSHOT)) {
          b.append(e.hasId() ? "id: "+e.getId() : "path: "+e.getPath());
          ce++;
          if (e.hasId()) {
            String msg = "No match found in the generated snapshot: check that the path and definitions are legal in the differential (including order)";
            messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.VALUE, url+"#"+e.getId(), msg, ValidationMessage.IssueSeverity.ERROR));
          }
        }
      }
      if (!Utilities.noString(b.toString())) {
        String msg = "The profile "+derived.getUrl()+" has "+ce+" "+Utilities.pluralize("element", ce)+" in the differential ("+b.toString()+") that don't have a matching element in the snapshot: check that the path and definitions are legal in the differential (including order)";
        System.out.println("Error in snapshot generation: "+msg);
        if (!debug) {
          System.out.println("Differential: ");
          for (ElementDefinition ed : derived.getDifferential().getElement())
            System.out.println("  "+ed.getId()+" = "+ed.getPath()+" : "+typeSummaryWithProfile(ed)+"["+ed.getMin()+".."+ed.getMax()+"]"+sliceSummary(ed)+"  "+constraintSummary(ed));
          System.out.println("Snapshot: ");
          for (ElementDefinition ed : derived.getSnapshot().getElement())
            System.out.println("  "+ed.getId()+" = "+ed.getPath()+" : "+typeSummaryWithProfile(ed)+"["+ed.getMin()+".."+ed.getMax()+"]"+sliceSummary(ed)+"  "+constraintSummary(ed));
        }
        if (exception)
          throw new DefinitionException(msg);
        else
          messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.VALUE, url, msg, ValidationMessage.IssueSeverity.ERROR));
      }
      // hack around a problem in R4 definitions (somewhere?)
      for (ElementDefinition ed : derived.getSnapshot().getElement()) {
        for (ElementDefinitionMappingComponent mm : ed.getMapping()) {
          if (mm.hasMap()) {
            mm.setMap(mm.getMap().trim());
          }
        }
        for (ElementDefinitionConstraintComponent s : ed.getConstraint()) {
          if (s.hasSource()) {
            String ref = s.getSource();
            if (!Utilities.isAbsoluteUrl(ref)) {
              if (ref.contains(".")) {
                s.setSource("http://hl7.org/fhir/StructureDefinition/"+ref.substring(0, ref.indexOf("."))+"#"+ref);
              } else {
                s.setSource("http://hl7.org/fhir/StructureDefinition/"+ref);
              }
            }  
          }
        }
      }
      if (derived.getDerivation() == TypeDerivationRule.SPECIALIZATION) {
        for (ElementDefinition ed : derived.getSnapshot().getElement()) {
          if (!ed.hasBase()) {
            ed.getBase().setPath(ed.getPath()).setMin(ed.getMin()).setMax(ed.getMax());
          }
        }
      }
      // last, check for wrong profiles or target profiles
      for (ElementDefinition ed : derived.getSnapshot().getElement()) {
        for (TypeRefComponent t : ed.getType()) {
          for (UriType u : t.getProfile()) {
            StructureDefinition sd = context.fetchResource(StructureDefinition.class, u.getValue());
            if (sd == null) {
              if (xver != null && xver.matchingUrl(u.getValue()) && xver.status(u.getValue()) == XVerExtensionStatus.Valid) {
                sd = xver.makeDefinition(u.getValue());              
              }
            }
            if (sd == null) {
              if (messages != null) {
                messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.VALUE, url+"#"+ed.getId(), "The type of profile "+u.getValue()+" cannot be checked as the profile is not known", IssueSeverity.WARNING));
              }
            } else {
              String wt = t.getWorkingCode();
              if (ed.getPath().equals("Bundle.entry.response.outcome")) {
                wt = "OperationOutcome";
              }
              if (!sd.getType().equals(wt)) {
                boolean ok = isCompatibleType(wt, sd);
                if (!ok) {
                  String smsg = "The profile "+u.getValue()+" has type "+sd.getType()+" which is not consistent with the stated type "+wt;
                  if (exception)
                    throw new DefinitionException(smsg);
                  else
                    messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.VALUE, url+"#"+ed.getId(), smsg, IssueSeverity.ERROR));
                }
              }
            }
          }
        }
      }
    } catch (Exception e) {
      // if we had an exception generating the snapshot, make sure we don't leave any half generated snapshot behind
      derived.setSnapshot(null);
      derived.clearUserData("profileutils.snapshot.generating");
      throw e;
    }
    derived.clearUserData("profileutils.snapshot.generating");
  }

  public void checkDifferentialBaseType(StructureDefinition derived) throws Error {
    if (derived.hasDifferential() && !derived.getDifferential().getElementFirstRep().getPath().contains(".") && !derived.getDifferential().getElementFirstRep().getType().isEmpty()) {
      if (wantFixDifferentialFirstElementType && typeMatchesAncestor(derived.getDifferential().getElementFirstRep().getType(), derived.getBaseDefinition())) {
        derived.getDifferential().getElementFirstRep().getType().clear();
      } else if (derived.getKind() != StructureDefinitionKind.LOGICAL) {
        throw new Error(context.formatMessage(I18nConstants.TYPE_ON_FIRST_DIFFERENTIAL_ELEMENT));
      }
    }
  }

  private boolean typeMatchesAncestor(List<TypeRefComponent> type, String baseDefinition) {
    StructureDefinition sd = context.fetchResource(StructureDefinition.class, baseDefinition);
    return sd != null && type.size() == 1 && sd.getType().equals(type.get(0).getCode()); 
  }

  private String typeName(String type) {
    if (Utilities.isAbsoluteUrl(type)) {
      return type.substring(type.lastIndexOf("/")+1);
    } else {
      return type;
    }
  }

  private void checkGroupConstraints(StructureDefinition derived) {
    List<ElementDefinition> toRemove = new ArrayList<>();
//    List<ElementDefinition> processed = new ArrayList<>();
    for (ElementDefinition element : derived.getSnapshot().getElement()) {
      if (!toRemove.contains(element) && !element.hasSlicing() && !"0".equals(element.getMax())) {
        checkForChildrenInGroup(derived, toRemove, element);
      }
    }
    derived.getSnapshot().getElement().removeAll(toRemove);
  }

  public void checkForChildrenInGroup(StructureDefinition derived, List<ElementDefinition> toRemove, ElementDefinition element) throws Error {
    List<ElementDefinition> children = getChildren(derived, element);
    List<ElementChoiceGroup> groups = readChoices(element, children);
    for (ElementChoiceGroup group : groups) {
//      System.out.println(children);
      String mandated = null;
      Set<String> names = new HashSet<>();
      for (ElementDefinition ed : children) {
        String name = tail(ed.getPath());
        if (names.contains(name)) {
          throw new Error("huh?");
        } else {
          names.add(name);
        }
        if (group.getElements().contains(name)) {
          if (ed.getMin() == 1) {
            if (mandated == null) {
              mandated = name;
            } else {
              throw new Error("Error: there are two mandatory elements in "+derived.getUrl()+" when there can only be one: "+mandated+" and "+name);
            }
          }
        }
      }
      if (mandated != null) {
        for (ElementDefinition ed : children) {
          String name = tail(ed.getPath());
          if (group.getElements().contains(name) && !mandated.equals(name)) {
            ed.setMax("0");
            addAllChildren(derived, ed, toRemove);
          }
        }
      }
    }
  }

  private List<ElementDefinition> getChildren(StructureDefinition derived, ElementDefinition element) {
    List<ElementDefinition> elements = derived.getSnapshot().getElement();
    int index = elements.indexOf(element) + 1;
    String path = element.getPath()+".";
    List<ElementDefinition> list = new ArrayList<>();
    while (index < elements.size()) {
      ElementDefinition e = elements.get(index);
      String p = e.getPath();
      if (p.startsWith(path) && !e.hasSliceName()) {
        if (!p.substring(path.length()).contains(".")) {
          list.add(e);
        }
        index++;
      } else  {
        break;
      }
    }
    return list;
  }

  private void addAllChildren(StructureDefinition derived, ElementDefinition element, List<ElementDefinition> toRemove) {
    List<ElementDefinition> children = getChildList(derived, element);
    for (ElementDefinition child : children) {
      toRemove.add(child);
      addAllChildren(derived, child, toRemove);
    }
  }

  private void checkDifferential(List<ElementDefinition> elements, String type, String url) {
    boolean first = true;
    for (ElementDefinition ed : elements) {
      if (!ed.hasPath()) {
        throw new FHIRException(context.formatMessage(I18nConstants.NO_PATH_ON_ELEMENT_IN_DIFFERENTIAL_IN_, url));
      }
      String p = ed.getPath();
      if (p == null) {
        throw new FHIRException(context.formatMessage(I18nConstants.NO_PATH_VALUE_ON_ELEMENT_IN_DIFFERENTIAL_IN_, url));
      }
      if (!((first && type.equals(p)) || p.startsWith(type+"."))) {
        throw new FHIRException(context.formatMessage(I18nConstants.ILLEGAL_PATH__IN_DIFFERENTIAL_IN__MUST_START_WITH_, p, url, type, (first ? " (or be '"+type+"')" : "")));
      }
      if (p.contains(".")) {
        // Element names (the parts of a path delineated by the '.' character) SHALL NOT contain whitespace (i.e. Unicode characters marked as whitespace)
        // Element names SHALL NOT contain the characters ,:;'"/|?!@#$%^&*()[]{}
        // Element names SHOULD not contain non-ASCII characters
        // Element names SHALL NOT exceed 64 characters in length
        String[] pl = p.split("\\.");
        for (String pp : pl) {
          if (pp.length() < 1) {
            throw new FHIRException(context.formatMessage(I18nConstants.ILLEGAL_PATH__IN_DIFFERENTIAL_IN__NAME_PORTION_MISING_, p, url));
          }
          if (pp.length() > 64) {
            throw new FHIRException(context.formatMessage(I18nConstants.ILLEGAL_PATH__IN_DIFFERENTIAL_IN__NAME_PORTION_EXCEEDS_64_CHARS_IN_LENGTH, p, url));
          }
          for (char ch : pp.toCharArray()) {
            if (Character.isWhitespace(ch)) {
              throw new FHIRException(context.formatMessage(I18nConstants.ILLEGAL_PATH__IN_DIFFERENTIAL_IN__NO_UNICODE_WHITESPACE, p, url));
            }
            if (Utilities.existsInList(ch, ',', ':', ';', '\'', '"', '/', '|', '?', '!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '{', '}')) {
              throw new FHIRException(context.formatMessage(I18nConstants.ILLEGAL_PATH__IN_DIFFERENTIAL_IN__ILLEGAL_CHARACTER_, p, url, ch));
            }
            if (ch < ' ' || ch > 'z') {
              throw new FHIRException(context.formatMessage(I18nConstants.ILLEGAL_PATH__IN_DIFFERENTIAL_IN__ILLEGAL_CHARACTER_, p, url, ch));
            }
          }
          if (pp.contains("[") || pp.contains("]")) {
            if (!pp.endsWith("[x]") || (pp.substring(0, pp.length()-3).contains("[") || (pp.substring(0, pp.length()-3).contains("]")))) {
              throw new FHIRException(context.formatMessage(I18nConstants.ILLEGAL_PATH__IN_DIFFERENTIAL_IN__ILLEGAL_CHARACTERS_, p, url));
            }
          }
        }
      }
    }    
  }


  private boolean isCompatibleType(String base, StructureDefinition sdt) {
    StructureDefinition sdb = context.fetchTypeDefinition(base);
    if (sdb.getType().equals(sdt.getType())) {
      return true;
    }
    StructureDefinition sd = context.fetchTypeDefinition(sdt.getType());
    while (sd != null) {
      if (sd.getType().equals(sdb.getType())) {
        return true;
      }
      if (sd.getUrl().equals(sdb.getUrl())) {
        return true;
      }
      sd = context.fetchResource(StructureDefinition.class, sd.getBaseDefinition()); 
    }
    return false;
  }


  private StructureDefinitionDifferentialComponent cloneDiff(StructureDefinitionDifferentialComponent source) {
    StructureDefinitionDifferentialComponent diff = new StructureDefinitionDifferentialComponent();
    for (ElementDefinition sed : source.getElement()) {
      ElementDefinition ted = sed.copy();
      diff.getElement().add(ted);
      ted.setUserData("diff-source", sed);
    }
    return diff;
  }

  private StructureDefinitionSnapshotComponent cloneSnapshot(StructureDefinitionSnapshotComponent source, String baseType, String derivedType) {
        StructureDefinitionSnapshotComponent diff = new StructureDefinitionSnapshotComponent();
    for (ElementDefinition sed : source.getElement()) {
      ElementDefinition ted = sed.copy();
      ted.setId(ted.getId().replaceFirst(baseType,derivedType));
      ted.setPath(ted.getPath().replaceFirst(baseType,derivedType));
      diff.getElement().add(ted);
    }
    return diff;
  }

  private String constraintSummary(ElementDefinition ed) {
    CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder();
    if (ed.hasPattern())
      b.append("pattern="+ed.getPattern().fhirType());
    if (ed.hasFixed())
      b.append("fixed="+ed.getFixed().fhirType());
    if (ed.hasConstraint())
      b.append("constraints="+ed.getConstraint().size());
    return b.toString();
  }


  private String sliceSummary(ElementDefinition ed) {
    if (!ed.hasSlicing() && !ed.hasSliceName())
      return "";
    if (ed.hasSliceName())
      return " (slicename = "+ed.getSliceName()+")";
    
    StringBuilder b = new StringBuilder();
    boolean first = true;
    for (ElementDefinitionSlicingDiscriminatorComponent d : ed.getSlicing().getDiscriminator()) {
      if (first) 
        first = false;
      else
        b.append("|");
      b.append(d.getPath());
    }
    return " (slicing by "+b.toString()+")";
  }


  private String typeSummary(ElementDefinition ed) {
    StringBuilder b = new StringBuilder();
    boolean first = true;
    for (TypeRefComponent tr : ed.getType()) {
      if (first) 
        first = false;
      else
        b.append("|");
      b.append(tr.getWorkingCode());
    }
    return b.toString();
  }

  private String typeSummaryWithProfile(ElementDefinition ed) {
    StringBuilder b = new StringBuilder();
    boolean first = true;
    for (TypeRefComponent tr : ed.getType()) {
      if (first) 
        first = false;
      else
        b.append("|");
      b.append(tr.getWorkingCode());
      if (tr.hasProfile()) {
        b.append("(");
        b.append(tr.getProfile());
        b.append(")");
        
      }
    }
    return b.toString();
  }


  private boolean findMatchingElement(String id, List<ElementDefinition> list) {
    for (ElementDefinition ed : list) {
      if (ed.getId().equals(id))
        return true;
      if (id.endsWith("[x]")) {
        if (ed.getId().startsWith(id.substring(0, id.length()-3)) && !ed.getId().substring(id.length()-3).contains("."))
          return true;
      }
    }
    return false;
  }


  /**
   * @param trimDifferential
   * @param srcSD 
   * @throws DefinitionException, FHIRException 
   * @throws Exception
   */
  private ElementDefinition processPaths(String indent, StructureDefinitionSnapshotComponent result, StructureDefinitionSnapshotComponent base, StructureDefinitionDifferentialComponent differential, int baseCursor, int diffCursor, int baseLimit,
      int diffLimit, String url, String webUrl, String profileName, String contextPathSrc, String contextPathDst, boolean trimDifferential, String contextName, String resultPathBase, boolean slicingDone, ElementDefinition slicer, String typeSlicingPath, List<ElementRedirection> redirector, StructureDefinition srcSD) throws DefinitionException, FHIRException {
    if (debug) {
      System.out.println(indent+"PP @ "+resultPathBase+" / "+contextPathSrc+" : base = "+baseCursor+" to "+baseLimit+", diff = "+diffCursor+" to "+diffLimit+" (slicing = "+slicingDone+", k "+(redirector == null ? "null" : redirector.toString())+")");
    }
    ElementDefinition res = null; 
    List<TypeSlice> typeList = new ArrayList<>();
    // just repeat processing entries until we run out of our allowed scope (1st entry, the allowed scope is all the entries)
    while (baseCursor <= baseLimit) {
      // get the current focus of the base, and decide what to do
      ElementDefinition currentBase = base.getElement().get(baseCursor);
      String cpath = fixedPathSource(contextPathSrc, currentBase.getPath(), redirector);
      if (debug) {
        System.out.println(indent+" - "+cpath+": base = "+baseCursor+" ("+descED(base.getElement(),baseCursor)+") to "+baseLimit+" ("+descED(base.getElement(),baseLimit)+"), diff = "+diffCursor+" ("+descED(differential.getElement(),diffCursor)+") to "+diffLimit+" ("+descED(differential.getElement(),diffLimit)+") "+
           "(slicingDone = "+slicingDone+") (diffpath= "+(differential.getElement().size() > diffCursor ? differential.getElement().get(diffCursor).getPath() : "n/a")+")");
      }
      List<ElementDefinition> diffMatches = getDiffMatches(differential, cpath, diffCursor, diffLimit, profileName); // get a list of matching elements in scope

      // in the simple case, source is not sliced.
      if (!currentBase.hasSlicing() || cpath.equals(typeSlicingPath)) {
        if (diffMatches.isEmpty()) { // the differential doesn't say anything about this item
          // so we just copy it in
          ElementDefinition outcome = updateURLs(url, webUrl, currentBase.copy());
          outcome.setPath(fixedPathDest(contextPathDst, outcome.getPath(), redirector, contextPathSrc));
          updateFromBase(outcome, currentBase);
          markDerived(outcome);
          if (resultPathBase == null)
            resultPathBase = outcome.getPath();
          else if (!outcome.getPath().startsWith(resultPathBase))
            throw new DefinitionException(context.formatMessage(I18nConstants.ADDING_WRONG_PATH__OUTCOMEGETPATH___RESULTPATHBASE__, outcome.getPath(), resultPathBase));
          result.getElement().add(outcome);
          if (hasInnerDiffMatches(differential, cpath, diffCursor, diffLimit, base.getElement(), true)) {
            // well, the profile walks into this, so we need to as well
            // did we implicitly step into a new type?
            if (baseHasChildren(base, currentBase)) { // not a new type here
              processPaths(indent+"  ", result, base, differential, baseCursor+1, diffCursor, baseLimit, diffLimit, url, webUrl, profileName, contextPathSrc, contextPathDst, trimDifferential, contextName, resultPathBase, false, null, null, redirector, srcSD);
              baseCursor = indexOfFirstNonChild(base, currentBase, baseCursor+1, baseLimit);
            } else {
              if (outcome.getType().size() == 0 && !outcome.hasContentReference()) {
                throw new DefinitionException(context.formatMessage(I18nConstants._HAS_NO_CHILDREN__AND_NO_TYPES_IN_PROFILE_, cpath, differential.getElement().get(diffCursor).getPath(), profileName));
              }
              boolean nonExtension = false;
              if (outcome.getType().size() > 1) {
                for (TypeRefComponent t : outcome.getType()) {
                  if (!t.getWorkingCode().equals("Reference")) {
                    for (ElementDefinition ed : diffMatches) {
                      if (ed != diffMatches.get(0) && !ed.getPath().endsWith(".extension")) {
                        nonExtension = true;
                      }
                    }
                  }
                }
              }
              int start = diffCursor;
              while (differential.getElement().size() > diffCursor && pathStartsWith(differential.getElement().get(diffCursor).getPath(), cpath+"."))
                diffCursor++;
              if (nonExtension) {
                throw new DefinitionException(context.formatMessage(I18nConstants._HAS_CHILDREN__AND_MULTIPLE_TYPES__IN_PROFILE_, cpath, differential.getElement().get(diffCursor).getPath(), typeCode(outcome.getType()), profileName));
              } 
              if (outcome.hasContentReference()) {                
                ElementDefinitionResolution tgt = getElementById(srcSD, base.getElement(), outcome.getContentReference());
                if (tgt == null)
                  throw new DefinitionException(context.formatMessage(I18nConstants.UNABLE_TO_RESOLVE_REFERENCE_TO_, outcome.getContentReference()));
                replaceFromContentReference(outcome, tgt.getElement());
                if (tgt.getSource() != srcSD) {
                  base = tgt.getSource().getSnapshot();
                  int nbc = base.getElement().indexOf(tgt.getElement())+1;
                  int nbl = nbc;
                  while (nbl < base.getElement().size() && base.getElement().get(nbl).getPath().startsWith(tgt.getElement().getPath()+"."))
                    nbl++;
                  processPaths(indent+"  ", result, base, differential, nbc, start - 1, nbl-1, diffCursor - 1, url, webUrl, profileName, tgt.getElement().getPath(), diffMatches.get(0).getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirectorStack(redirector, outcome, cpath), tgt.getSource());
                } else {
                  int nbc = base.getElement().indexOf(tgt.getElement())+1;
                  int nbl = nbc;
                  while (nbl < base.getElement().size() && base.getElement().get(nbl).getPath().startsWith(tgt.getElement().getPath()+"."))
                    nbl++;
                  System.out.println("Test!");
                  processPaths(indent+"  ", result, base, differential, nbc, start, nbl-1, diffCursor-1, url, webUrl, profileName, tgt.getElement().getPath(), outcome.getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirectorStack(redirector, outcome, cpath), srcSD);
                }
              } else {
                StructureDefinition dt = outcome.getType().size() > 1 ? context.fetchTypeDefinition("Element") : getProfileForDataType(outcome.getType().get(0));
                if (dt == null) {
                  throw new DefinitionException(context.formatMessage(I18nConstants.UNKNOWN_TYPE__AT_, outcome.getType().get(0), cpath));
                }
                contextName = dt.getUrl();
                if (redirector.isEmpty()) {
                  processPaths(indent+"  ", result, dt.getSnapshot(), differential, 1 /* starting again on the data type, but skip the root */, start, dt.getSnapshot().getElement().size()-1,
                      diffCursor-1, url, getWebUrl(dt, webUrl, indent), profileName, cpath, outcome.getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirector, srcSD);
                } else {
                  processPaths(indent+"  ", result, dt.getSnapshot(), differential, 1 /* starting again on the data type, but skip the root */, start, dt.getSnapshot().getElement().size()-1,
                      diffCursor-1, url, getWebUrl(dt, webUrl, indent), profileName, cpath, outcome.getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirectorStack(redirector, currentBase, cpath), srcSD);
                }
              }
            }
          }
          baseCursor++;
        } else if (diffMatches.size() == 1 && (slicingDone || (!isImplicitSlicing(diffMatches.get(0), cpath) && !(diffMatches.get(0).hasSlicing() || (isExtension(diffMatches.get(0)) && diffMatches.get(0).hasSliceName()))))) {// one matching element in the differential
          ElementDefinition template = null;
          if (diffMatches.get(0).hasType() && "Reference".equals(diffMatches.get(0).getType().get(0).getWorkingCode()) && !isValidType(diffMatches.get(0).getType().get(0), currentBase)) {
            throw new DefinitionException(context.formatMessage(I18nConstants.VALIDATION_VAL_ILLEGAL_TYPE_CONSTRAINT, url, diffMatches.get(0).getPath(), diffMatches.get(0).getType().get(0), currentBase.typeSummary()));            
          }
          if (diffMatches.get(0).hasType() && diffMatches.get(0).getType().size() == 1 && diffMatches.get(0).getType().get(0).hasProfile() && !"Reference".equals(diffMatches.get(0).getType().get(0).getWorkingCode())) {
            CanonicalType p = diffMatches.get(0).getType().get(0).getProfile().get(0);
            StructureDefinition sd = context.fetchResource(StructureDefinition.class, p.getValue());
            if (sd == null && xver != null && xver.matchingUrl(p.getValue())) {
              switch (xver.status(p.getValue())) {
              case BadVersion: throw new FHIRException("Reference to invalid version in extension url "+p.getValue());
              case Invalid: throw new FHIRException("Reference to invalid extension "+p.getValue());
              case Unknown: throw new FHIRException("Reference to unknown extension "+p.getValue()); 
              case Valid: 
                sd = xver.makeDefinition(p.getValue());
                generateSnapshot(context.fetchTypeDefinition("Extension"), sd, sd.getUrl(), webUrl, sd.getName());
              }
            }
            if (sd != null) {
              if (!isMatchingType(sd, diffMatches.get(0).getType(), p.getExtensionString(ToolingExtensions.EXT_PROFILE_ELEMENT))) {
                throw new DefinitionException(context.formatMessage(I18nConstants.VALIDATION_VAL_PROFILE_WRONGTYPE2, sd.getUrl(), diffMatches.get(0).getPath(), sd.getType(), p.getValue(), diffMatches.get(0).getType().get(0).getWorkingCode()));            
              }
              if (isGenerating(sd)) {
                // this is a special case, because we're only going to access the first element, and we can rely on the fact that it's already populated.
                // but we check anyway
                if (sd.getSnapshot().getElementFirstRep().isEmpty()) {
                  throw new FHIRException(context.formatMessage(I18nConstants.ATTEMPT_TO_USE_A_SNAPSHOT_ON_PROFILE__AS__BEFORE_IT_IS_GENERATED, sd.getUrl(), "Source for first element"));
                }
              } else if (!sd.hasSnapshot()) {
                StructureDefinition sdb = context.fetchResource(StructureDefinition.class, sd.getBaseDefinition());
                if (sdb == null)
                  throw new DefinitionException(context.formatMessage(I18nConstants.UNABLE_TO_FIND_BASE__FOR_, sd.getBaseDefinition(), sd.getUrl()));
                checkNotGenerating(sdb, "an extension base");
                generateSnapshot(sdb, sd, sd.getUrl(), (sdb.hasUserData("path")) ? Utilities.extractBaseUrl(sdb.getUserString("path")) : webUrl, sd.getName());
              }
              ElementDefinition src;
              if (p.hasExtension(ToolingExtensions.EXT_PROFILE_ELEMENT)) {
                 src = null;
                 String eid = p.getExtensionString(ToolingExtensions.EXT_PROFILE_ELEMENT);
                 for (ElementDefinition t : sd.getSnapshot().getElement()) {
                   if (eid.equals(t.getId()))
                     src = t;
                 }
                 if (src == null)
                  throw new DefinitionException(context.formatMessage(I18nConstants.UNABLE_TO_FIND_ELEMENT__IN_, eid, p.getValue()));
              } else 
                src = sd.getSnapshot().getElement().get(0);
              template = src.copy().setPath(currentBase.getPath());
              template.setSliceName(null);
              // temporary work around
              if (!"Extension".equals(diffMatches.get(0).getType().get(0).getCode())) {
                template.setMin(currentBase.getMin());
                template.setMax(currentBase.getMax());
              }
            }
          } 
          if (template == null)
            template = currentBase.copy();
          else
            // some of what's in currentBase overrides template
            template = fillOutFromBase(template, currentBase);
          
          ElementDefinition outcome = updateURLs(url, webUrl, template);
          outcome.setPath(fixedPathDest(contextPathDst, outcome.getPath(), redirector, contextPathSrc));
          if (res == null)
            res = outcome;
          updateFromBase(outcome, currentBase);
          if (diffMatches.get(0).hasSliceName()) {
            outcome.setSliceName(diffMatches.get(0).getSliceName());
            if (!diffMatches.get(0).hasMin() && (diffMatches.size() > 1 || slicer == null || slicer.getSlicing().getRules() != SlicingRules.CLOSED)  && !currentBase.hasSliceName()) {
              if (!cpath.endsWith("xtension.value[x]")) { // hack work around for problems with snapshots in official releases
                outcome.setMin(0);
              }
            }
          }
          updateFromDefinition(outcome, diffMatches.get(0), profileName, trimDifferential, url, srcSD);
          removeStatusExtensions(outcome);
//          if (outcome.getPath().endsWith("[x]") && outcome.getType().size() == 1 && !outcome.getType().get(0).getCode().equals("*") && !diffMatches.get(0).hasSlicing()) // if the base profile allows multiple types, but the profile only allows one, rename it
//            outcome.setPath(outcome.getPath().substring(0, outcome.getPath().length()-3)+Utilities.capitalize(outcome.getType().get(0).getCode()));
          outcome.setSlicing(null);
          if (resultPathBase == null)
            resultPathBase = outcome.getPath();
          else if (!outcome.getPath().startsWith(resultPathBase))
            throw new DefinitionException(context.formatMessage(I18nConstants.ADDING_WRONG_PATH));
          result.getElement().add(outcome);
          baseCursor++;
          diffCursor = differential.getElement().indexOf(diffMatches.get(0))+1;
          if (diffLimit >= diffCursor && outcome.getPath().contains(".") && (isDataType(outcome.getType()) || isBaseResource(outcome.getType()) || outcome.hasContentReference())) {  // don't want to do this for the root, since that's base, and we're already processing it
            if (pathStartsWith(differential.getElement().get(diffCursor).getPath(), diffMatches.get(0).getPath()+".") && !baseWalksInto(base.getElement(), baseCursor)) {
              if (outcome.getType().size() > 1) {
                if (outcome.getPath().endsWith("[x]") && !diffMatches.get(0).getPath().endsWith("[x]")) {
                  String en = tail(outcome.getPath());
                  String tn = tail(diffMatches.get(0).getPath());
                  String t = tn.substring(en.length()-3);
                  if (isPrimitive(Utilities.uncapitalize(t)))
                    t = Utilities.uncapitalize(t);
                  List<TypeRefComponent> ntr = getByTypeName(outcome.getType(), t); // keep any additional information
                  if (ntr.isEmpty()) 
                    ntr.add(new TypeRefComponent().setCode(t));
                  outcome.getType().clear();
                  outcome.getType().addAll(ntr);
                }
                if (outcome.getType().size() > 1)
                  for (TypeRefComponent t : outcome.getType()) {
                    if (!t.getCode().equals("Reference")) {
                      boolean nonExtension = false;
                      for (ElementDefinition ed : diffMatches)
                        if (ed != diffMatches.get(0) && !ed.getPath().endsWith(".extension"))
                          nonExtension = true;
                      if (nonExtension)
                        throw new DefinitionException(context.formatMessage(I18nConstants._HAS_CHILDREN__AND_MULTIPLE_TYPES__IN_PROFILE_, diffMatches.get(0).getPath(), differential.getElement().get(diffCursor).getPath(), typeCode(outcome.getType()), profileName));
                    }
                }
              }
              int start = diffCursor;
              while (diffCursor <= diffLimit && differential.getElement().size() > diffCursor && pathStartsWith(differential.getElement().get(diffCursor).getPath(), diffMatches.get(0).getPath()+"."))
                diffCursor++;
              if (outcome.hasContentReference()) {
                ElementDefinitionResolution tgt = getElementById(srcSD, base.getElement(), outcome.getContentReference());
                if (tgt == null)
                  throw new DefinitionException(context.formatMessage(I18nConstants.UNABLE_TO_RESOLVE_REFERENCE_TO_, outcome.getContentReference()));
                replaceFromContentReference(outcome, tgt.getElement());
                if (tgt.getSource() != srcSD) {
                  base = tgt.getSource().getSnapshot();
                  int nbc = base.getElement().indexOf(tgt.getElement())+1;
                  int nbl = nbc;
                  while (nbl < base.getElement().size() && base.getElement().get(nbl).getPath().startsWith(tgt.getElement().getPath()+"."))
                    nbl++;
                  processPaths(indent+"  ", result, base, differential, nbc, start - 1, nbl-1, diffCursor - 1, url, webUrl, profileName, tgt.getElement().getPath(), diffMatches.get(0).getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirectorStack(redirector, outcome, cpath), tgt.getSource());
                } else {
                  int nbc = base.getElement().indexOf(tgt.getElement())+1;
                  int nbl = nbc;
                  while (nbl < base.getElement().size() && base.getElement().get(nbl).getPath().startsWith(tgt.getElement().getPath()+"."))
                    nbl++;
                   processPaths(indent+"  ", result, base, differential, nbc, start - 1, nbl-1, diffCursor - 1, url, webUrl, profileName, tgt.getElement().getPath(), diffMatches.get(0).getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirectorStack(redirector, outcome, cpath), srcSD);
                }
              } else {
                StructureDefinition dt = outcome.getType().size() == 1 ? getProfileForDataType(outcome.getType().get(0)) : getProfileForDataType("Element");
                if (dt == null)
                  throw new DefinitionException(context.formatMessage(I18nConstants._HAS_CHILDREN__FOR_TYPE__IN_PROFILE__BUT_CANT_FIND_TYPE, diffMatches.get(0).getPath(), differential.getElement().get(diffCursor).getPath(), typeCode(outcome.getType()), profileName));
                contextName = dt.getUrl();
                processPaths(indent+"  ", result, dt.getSnapshot(), differential, 1 /* starting again on the data type, but skip the root */, start, dt.getSnapshot().getElement().size()-1,
                    diffCursor - 1, url, getWebUrl(dt, webUrl, indent), profileName+pathTail(diffMatches, 0), diffMatches.get(0).getPath(), outcome.getPath(), trimDifferential, contextName, resultPathBase, false, null, null, new ArrayList<ElementRedirection>(), srcSD);
              }
            }
          }
        } else if (diffsConstrainTypes(diffMatches, cpath, typeList)) {
          int start = 0;
          int nbl = findEndOfElement(base, baseCursor);
          int ndc = differential.getElement().indexOf(diffMatches.get(0));
          ElementDefinition elementToRemove = null;
          boolean shortCut = !typeList.isEmpty() && typeList.get(0).type != null;
          // we come here whether they are sliced in the diff, or whether the short cut is used.
          if (shortCut) {
            // this is the short cut method, we've just dived in and specified a type slice.
            // in R3 (and unpatched R4, as a workaround right now...
            if (!FHIRVersion.isR4Plus(context.getVersion()) || !newSlicingProcessing) { // newSlicingProcessing is a work around for editorial loop dependency
              // we insert a cloned element with the right types at the start of the diffMatches
              ElementDefinition ed = new ElementDefinition();
              ed.setPath(determineTypeSlicePath(diffMatches.get(0).getPath(), cpath));
              for (TypeSlice ts : typeList) 
                ed.addType().setCode(ts.type);
              ed.setSlicing(new ElementDefinitionSlicingComponent());
              ed.getSlicing().addDiscriminator().setType(DiscriminatorType.TYPE).setPath("$this");
              ed.getSlicing().setRules(SlicingRules.CLOSED);
              ed.getSlicing().setOrdered(false);
              diffMatches.add(0, ed);
              differential.getElement().add(ndc, ed);
              elementToRemove = ed;
            } else {
              // as of R4, this changed; if there's no slice, there's no constraint on the slice types, only one the type.
              // so the element we insert specifies no types (= all types) allowed in the base, not just the listed type.
              // see also discussion here: https://chat.fhir.org/#narrow/stream/179177-conformance/topic/Slicing.20a.20non-repeating.20element
              ElementDefinition ed = new ElementDefinition();
              ed.setPath(determineTypeSlicePath(diffMatches.get(0).getPath(), cpath));
              ed.setSlicing(new ElementDefinitionSlicingComponent());
              ed.getSlicing().addDiscriminator().setType(DiscriminatorType.TYPE).setPath("$this");
              ed.getSlicing().setRules(SlicingRules.CLOSED);
              ed.getSlicing().setOrdered(false);
              diffMatches.add(0, ed);
              differential.getElement().add(ndc, ed);
              elementToRemove = ed;
            }
          }
          int ndl = findEndOfElement(differential, ndc);
          // the first element is setting up the slicing

          if (diffMatches.get(0).getSlicing().hasOrdered()) {
            if (diffMatches.get(0).getSlicing().getOrdered()) {
              throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__IN__TYPE_SLICING_WITH_SLICINGORDERED__TRUE, cpath, url));
            }
          }
          if (diffMatches.get(0).getSlicing().hasDiscriminator()) {
            if (diffMatches.get(0).getSlicing().getDiscriminator().size() != 1) {
              throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__IN__TYPE_SLICING_WITH_SLICINGDISCRIMINATORCOUNT__1, cpath, url));
            }
            if (diffMatches.get(0).getSlicing().getDiscriminatorFirstRep().getType() != DiscriminatorType.TYPE) {
              throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__IN__TYPE_SLICING_WITH_SLICINGDISCRIMINATORTYPE__TYPE, cpath, url));
            }
            if (!"$this".equals(diffMatches.get(0).getSlicing().getDiscriminatorFirstRep().getPath())) {
              throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__IN__TYPE_SLICING_WITH_SLICINGDISCRIMINATORPATH__THIS, cpath, url));
            }
          }
          // check the slice names too while we're at it...
          for (TypeSlice ts : typeList) {
              if (ts.type != null) {
                String tn = rootName(cpath)+Utilities.capitalize(ts.type);
                if (!ts.defn.hasSliceName()) {
                  ts.defn.setSliceName(tn);
                } else if (!ts.defn.getSliceName().equals(tn)) {
                  if (autoFixSliceNames) {
                    ts.defn.setSliceName(tn);
                  } else {
                    throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__SLICE_NAME_MUST_BE__BUT_IS_, (!Utilities.noString(contextPathSrc) ? contextPathSrc : cpath), tn, ts.defn.getSliceName()));
                  }
                } if (!ts.defn.hasType()) {
                  ts.defn.addType().setCode(ts.type);
                } else if (ts.defn.getType().size() > 1) {
                  throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__SLICE_FOR_TYPE__HAS_MORE_THAN_ONE_TYPE_, (!Utilities.noString(contextPathSrc) ? contextPathSrc : cpath), tn, ts.defn.typeSummary()));
                } else if (!ts.defn.getType().get(0).getCode().equals(ts.type)) {
                  throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__SLICE_FOR_TYPE__HAS_WRONG_TYPE_, (!Utilities.noString(contextPathSrc) ? contextPathSrc : cpath), tn, ts.defn.typeSummary()));
                }
              }
            }

          // ok passed the checks.
          // copy the root diff, and then process any children it has
          ElementDefinition e = processPaths(indent+"  ", result, base, differential, baseCursor, ndc, nbl, ndl, url, webUrl, profileName+pathTail(diffMatches, 0), contextPathSrc, contextPathDst, 
              trimDifferential, contextName, resultPathBase, true, null, null, redirector, srcSD);
          if (e==null)
            throw new FHIRException(context.formatMessage(I18nConstants.DID_NOT_FIND_TYPE_ROOT_, diffMatches.get(0).getPath()));
          // now set up slicing on the e (cause it was wiped by what we called.
          e.setSlicing(new ElementDefinitionSlicingComponent());
          e.getSlicing().addDiscriminator().setType(DiscriminatorType.TYPE).setPath("$this");
          e.getSlicing().setRules(SlicingRules.CLOSED); // type slicing is always closed; the differential might call it open, but that just means it's not constraining the slices it doesn't mention
          e.getSlicing().setOrdered(false);
         
          start++;

          String fixedType = null;
          // now process the siblings, which should each be type constrained - and may also have their own children
          // now we process the base scope repeatedly for each instance of the item in the differential list
          for (int i = start; i < diffMatches.size(); i++) {
            // our processing scope for the differential is the item in the list, and all the items before the next one in the list
            if (diffMatches.get(i).getMin() > 0) {
              if (diffMatches.size() > i+1) {
                throw new FHIRException(context.formatMessage(I18nConstants.INVALID_SLICING__THERE_IS_MORE_THAN_ONE_TYPE_SLICE_AT__BUT_ONE_OF_THEM__HAS_MIN__1_SO_THE_OTHER_SLICES_CANNOT_EXIST, diffMatches.get(i).getPath(), diffMatches.get(i).getSliceName()));
              } else {
                e.setMin(1);
              }
              fixedType = determineFixedType(diffMatches, fixedType, i);
            }
            ndc = differential.getElement().indexOf(diffMatches.get(i));
            ndl = findEndOfElement(differential, ndc);
            processPaths(indent+"  ", result, base, differential, baseCursor, ndc, nbl, ndl, url, webUrl, profileName+pathTail(diffMatches, i), contextPathSrc, contextPathDst, trimDifferential, contextName, resultPathBase, true, e, null, redirector, srcSD);
          }
          if (elementToRemove != null) {
            differential.getElement().remove(elementToRemove);
            ndl--;
          }
          if (fixedType != null) {
            for (Iterator<TypeRefComponent> iter = e.getType().iterator(); iter.hasNext(); ) {
              TypeRefComponent tr = iter.next();
              if (!tr.getCode().equals(fixedType)) {
                iter.remove();
              }
            }
          }
          if (!"0".equals(e.getMax())) {
            // check that there's a slice for each allowed types 
            Set<String> allowedTypes = getListOfTypes(e);
            for (TypeSlice t : typeList) {
              if (t.type != null) {
                allowedTypes.remove(t.type);
              } else if (t.getDefn().hasSliceName() && t.getDefn().getType().size() == 1) {
                allowedTypes.remove(t.getDefn().getType().get(0).getCode());              
              }
            }
            if (!allowedTypes.isEmpty()) {
              if (cpath.contains("xtension.value")) {
                for (Iterator<TypeRefComponent> iter = e.getType().iterator(); iter.hasNext(); ) {
                  TypeRefComponent tr = iter.next();
                  if (allowedTypes.contains(tr.getCode())) {
                    iter.remove();
                  }
                }
//                System.out.println("!!: Extension Error at "+cpath+": Allowed Types not sliced = "+allowedTypes+". !Extension!!");
//                throw new Error("Extension Error at "+cpath+": Allowed Types not sliced = "+allowedTypes+". !Extension!!");

              } else {
                e.getSlicing().setRules(SlicingRules.OPEN);
              }
            }
          }
          // ok, done with that - next in the base list
          baseCursor = nbl+1;
          diffCursor = ndl+1;
          
        } else {
          // ok, the differential slices the item. Let's check our pre-conditions to ensure that this is correct
          if (!unbounded(currentBase) && !isSlicedToOneOnly(diffMatches.get(0)))
            // you can only slice an element that doesn't repeat if the sum total of your slices is limited to 1
            // (but you might do that in order to split up constraints by type)
            throw new DefinitionException(context.formatMessage(I18nConstants.ATTEMPT_TO_A_SLICE_AN_ELEMENT_THAT_DOES_NOT_REPEAT__FROM__IN_, currentBase.getPath(), currentBase.getPath(), contextName, url, diffMatches.get(0).getId(), sliceNames(diffMatches)));
          if (!diffMatches.get(0).hasSlicing() && !isExtension(currentBase)) // well, the diff has set up a slice, but hasn't defined it. this is an error
            throw new DefinitionException(context.formatMessage(I18nConstants.DIFFERENTIAL_DOES_NOT_HAVE_A_SLICE__B_OF_____IN_PROFILE_, currentBase.getPath(), baseCursor, baseLimit, diffCursor, diffLimit, url, cpath));

          // well, if it passed those preconditions then we slice the dest.
          int start = 0;
          int nbl = findEndOfElement(base, baseCursor);
//          if (diffMatches.size() > 1 && diffMatches.get(0).hasSlicing() && differential.getElement().indexOf(diffMatches.get(1)) > differential.getElement().indexOf(diffMatches.get(0))+1) {
          ElementDefinition slicerElement;
          if (diffMatches.size() > 1 && diffMatches.get(0).hasSlicing() && (nbl > baseCursor || differential.getElement().indexOf(diffMatches.get(1)) > differential.getElement().indexOf(diffMatches.get(0))+1)) { // there's a default set before the slices
            int ndc = differential.getElement().indexOf(diffMatches.get(0));
            int ndl = findEndOfElement(differential, ndc);
            ElementDefinition e = processPaths(indent+"  ", result, base, differential, baseCursor, ndc, nbl, ndl, url, webUrl, profileName+pathTail(diffMatches, 0), contextPathSrc, contextPathDst, 
                trimDifferential, contextName, resultPathBase, true, null, null, redirector, srcSD);
            if (e==null)
              throw new FHIRException(context.formatMessage(I18nConstants.DID_NOT_FIND_SINGLE_SLICE_, diffMatches.get(0).getPath()));
            e.setSlicing(diffMatches.get(0).getSlicing());
            slicerElement = e;
            start++;
          } else {
            // we're just going to accept the differential slicing at face value
            ElementDefinition outcome = updateURLs(url, webUrl, currentBase.copy());
            outcome.setPath(fixedPathDest(contextPathDst, outcome.getPath(), redirector, contextPathSrc));
            updateFromBase(outcome, currentBase);

            if (!diffMatches.get(0).hasSlicing())
              outcome.setSlicing(makeExtensionSlicing());
            else
              outcome.setSlicing(diffMatches.get(0).getSlicing().copy());
            if (!outcome.getPath().startsWith(resultPathBase))
              throw new DefinitionException(context.formatMessage(I18nConstants.ADDING_WRONG_PATH));
            result.getElement().add(outcome);
            slicerElement = outcome;
            
            // differential - if the first one in the list has a name, we'll process it. Else we'll treat it as the base definition of the slice.
            if (!diffMatches.get(0).hasSliceName()) {
              updateFromDefinition(outcome, diffMatches.get(0), profileName, trimDifferential, url, srcSD);
              removeStatusExtensions(outcome);
              if (!outcome.hasContentReference() && !outcome.hasType()) {
                throw new DefinitionException(context.formatMessage(I18nConstants.NOT_DONE_YET));
              }
              if (hasInnerDiffMatches(differential, currentBase.getPath(), diffCursor, diffLimit, base.getElement(), false)) {
                if (baseHasChildren(base, currentBase)) { // not a new type here
                  throw new Error("This situation is not yet handled (constrain slicing to 1..1 and fix base slice for inline structure - please report issue to grahame@fhir.org along with a test case that reproduces this error (@ "+cpath+" | "+currentBase.getPath()+")");
                } else {
                  StructureDefinition dt = getTypeForElement(differential, diffCursor, profileName, diffMatches, outcome);
                  contextName = dt.getUrl();
                  diffCursor++;
                  start = diffCursor;
                  while (differential.getElement().size() > diffCursor && pathStartsWith(differential.getElement().get(diffCursor).getPath(), cpath+"."))
                    diffCursor++;
                  diffCursor--;
                  processPaths(indent+"  ", result, dt.getSnapshot(), differential, 1 /* starting again on the data type, but skip the root */, start, dt.getSnapshot().getElement().size()-1,
                      diffCursor, url, getWebUrl(dt, webUrl, indent), profileName, cpath, outcome.getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirector, srcSD);
                }
              }
              start++;
              // result.getElement().remove(result.getElement().size()-1);
            } else 
              checkExtensionDoco(outcome);
          }
          // now, for each entry in the diff matches, we're going to process the base item
          // our processing scope for base is all the children of the current path
          int ndc = diffCursor;
          int ndl = diffCursor;
          for (int i = start; i < diffMatches.size(); i++) {
            // our processing scope for the differential is the item in the list, and all the items before the next one in the list
            ndc = differential.getElement().indexOf(diffMatches.get(i));
            ndl = findEndOfElement(differential, ndc);
/*            if (skipSlicingElement && i == 0) {
              ndc = ndc + 1;
              if (ndc > ndl)
                continue;
            }*/
            // now we process the base scope repeatedly for each instance of the item in the differential list
            processPaths(indent+"  ", result, base, differential, baseCursor, ndc, nbl, ndl, url, webUrl, profileName+pathTail(diffMatches, i), contextPathSrc, contextPathDst, trimDifferential, contextName, resultPathBase, true, slicerElement, null, redirector, srcSD);
          }
          // ok, done with that - next in the base list
          baseCursor = nbl+1;
          diffCursor = ndl+1;
        }
      } else {
        // the item is already sliced in the base profile.
        // here's the rules
        //  1. irrespective of whether the slicing is ordered or not, the definition order must be maintained
        //  2. slice element names have to match.
        //  3. new slices must be introduced at the end
        // corallory: you can't re-slice existing slices. is that ok?

        // we're going to need this:
        String path = currentBase.getPath();
        ElementDefinition original = currentBase;

        if (diffMatches.isEmpty()) {
          if (hasInnerDiffMatches(differential, path, diffCursor, diffLimit, base.getElement(), true)) {
            // so we just copy it in
            ElementDefinition outcome = updateURLs(url, webUrl, currentBase.copy());
            outcome.setPath(fixedPathDest(contextPathDst, outcome.getPath(), redirector, contextPathSrc));
            updateFromBase(outcome, currentBase);
            markDerived(outcome);
            if (resultPathBase == null)
              resultPathBase = outcome.getPath();
            else if (!outcome.getPath().startsWith(resultPathBase))
              throw new DefinitionException(context.formatMessage(I18nConstants.ADDING_WRONG_PATH));
            result.getElement().add(outcome);
            // the profile walks into this, so we need to as well
            // did we implicitly step into a new type?
            if (baseHasChildren(base, currentBase)) { // not a new type here
              processPaths(indent+"  ", result, base, differential, baseCursor+1, diffCursor, baseLimit, diffLimit, url, webUrl, profileName, contextPathSrc, contextPathDst, trimDifferential, contextName, resultPathBase, false, null, null, redirector, srcSD);
              baseCursor = indexOfFirstNonChild(base, currentBase, baseCursor, baseLimit);
            } else {
              StructureDefinition dt = getTypeForElement(differential, diffCursor, profileName, diffMatches, outcome);
              contextName = dt.getUrl();
              int start = diffCursor;
              while (differential.getElement().size() > diffCursor && pathStartsWith(differential.getElement().get(diffCursor).getPath(), cpath+"."))
                diffCursor++;
              processPaths(indent+"  ", result, dt.getSnapshot(), differential, 1 /* starting again on the data type, but skip the root */, start, dt.getSnapshot().getElement().size()-1,
                  diffCursor-1, url, getWebUrl(dt, webUrl, indent), profileName, cpath, outcome.getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirector, srcSD);
            }
            baseCursor++;
          } else {
            // the differential doesn't say anything about this item
            // copy across the currentbase, and all of its children and siblings
            while (baseCursor < base.getElement().size() && base.getElement().get(baseCursor).getPath().startsWith(path)) {
              ElementDefinition outcome = updateURLs(url, webUrl, base.getElement().get(baseCursor).copy());
              outcome.setPath(fixedPathDest(contextPathDst, outcome.getPath(), redirector, contextPathSrc));
              if (!outcome.getPath().startsWith(resultPathBase))
                throw new DefinitionException(context.formatMessage(I18nConstants.ADDING_WRONG_PATH_IN_PROFILE___VS_, profileName, outcome.getPath(), resultPathBase));
              result.getElement().add(outcome); // so we just copy it in
              baseCursor++;
            }
          }
        } else if (diffsConstrainTypes(diffMatches, cpath, typeList)) {
          int start = 0;
          int nbl = findEndOfElement(base, baseCursor);
          int ndc = differential.getElement().indexOf(diffMatches.get(0));
          ElementDefinition elementToRemove = null;
          boolean shortCut = (!typeList.isEmpty() && typeList.get(0).type != null) || (diffMatches.get(0).hasSliceName() && !diffMatches.get(0).hasSlicing());
          // we come here whether they are sliced in the diff, or whether the short cut is used.
          if (shortCut) {
            // this is the short cut method, we've just dived in and specified a type slice.
            // in R3 (and unpatched R4, as a workaround right now...
            if (!FHIRVersion.isR4Plus(context.getVersion()) || !newSlicingProcessing) { // newSlicingProcessing is a work around for editorial loop dependency
              // we insert a cloned element with the right types at the start of the diffMatches
              ElementDefinition ed = new ElementDefinition();
              ed.setPath(determineTypeSlicePath(diffMatches.get(0).getPath(), cpath));
              for (TypeSlice ts : typeList) 
                ed.addType().setCode(ts.type);
              ed.setSlicing(new ElementDefinitionSlicingComponent());
              ed.getSlicing().addDiscriminator().setType(DiscriminatorType.TYPE).setPath("$this");
              ed.getSlicing().setRules(SlicingRules.CLOSED);
              ed.getSlicing().setOrdered(false);
              diffMatches.add(0, ed);
              differential.getElement().add(ndc, ed);
              elementToRemove = ed;
            } else {
              // as of R4, this changed; if there's no slice, there's no constraint on the slice types, only one the type.
              // so the element we insert specifies no types (= all types) allowed in the base, not just the listed type.
              // see also discussion here: https://chat.fhir.org/#narrow/stream/179177-conformance/topic/Slicing.20a.20non-repeating.20element
              ElementDefinition ed = new ElementDefinition();
              ed.setPath(determineTypeSlicePath(diffMatches.get(0).getPath(), cpath));
              ed.setSlicing(new ElementDefinitionSlicingComponent());
              ed.getSlicing().addDiscriminator().setType(DiscriminatorType.TYPE).setPath("$this");
              ed.getSlicing().setRules(SlicingRules.CLOSED);
              ed.getSlicing().setOrdered(false);
              diffMatches.add(0, ed);
              differential.getElement().add(ndc, ed);
              elementToRemove = ed;
            }
          }
          int ndl = findEndOfElement(differential, ndc);
          // the first element is setting up the slicing

          if (diffMatches.get(0).getSlicing().hasOrdered()) {
            if (diffMatches.get(0).getSlicing().getOrdered()) {
              throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__IN__TYPE_SLICING_WITH_SLICINGORDERED__TRUE, cpath, url));
            }
          }
          if (diffMatches.get(0).getSlicing().hasDiscriminator()) {
            if (diffMatches.get(0).getSlicing().getDiscriminator().size() != 1) {
              throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__IN__TYPE_SLICING_WITH_SLICINGDISCRIMINATORCOUNT__1, cpath, url));
            }
            if (diffMatches.get(0).getSlicing().getDiscriminatorFirstRep().getType() != DiscriminatorType.TYPE) {
              throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__IN__TYPE_SLICING_WITH_SLICINGDISCRIMINATORTYPE__TYPE, cpath, url));
            }
            if (!"$this".equals(diffMatches.get(0).getSlicing().getDiscriminatorFirstRep().getPath())) {
              throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__IN__TYPE_SLICING_WITH_SLICINGDISCRIMINATORPATH__THIS, cpath, url));
            }
          }
          // check the slice names too while we're at it...
          for (TypeSlice ts : typeList) {
            if (ts.type != null) {
              String tn = rootName(cpath)+Utilities.capitalize(ts.type);
              if (!ts.defn.hasSliceName()) {
                ts.defn.setSliceName(tn);
              } else if (!ts.defn.getSliceName().equals(tn)) {
                throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__SLICE_NAME_MUST_BE__BUT_IS_, (!Utilities.noString(contextPathSrc) ? contextPathSrc : cpath), tn, ts.defn.getSliceName()));
              } if (!ts.defn.hasType()) {
                ts.defn.addType().setCode(ts.type);
              } else if (ts.defn.getType().size() > 1) {
                throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__SLICE_FOR_TYPE__HAS_MORE_THAN_ONE_TYPE_, (!Utilities.noString(contextPathSrc) ? contextPathSrc : cpath), tn, ts.defn.typeSummary()));
              } else if (!ts.defn.getType().get(0).getCode().equals(ts.type)) {
                throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT_PATH__SLICE_FOR_TYPE__HAS_WRONG_TYPE_, (!Utilities.noString(contextPathSrc) ? contextPathSrc : cpath), tn, ts.defn.typeSummary()));
              }
            }
          }

          // ok passed the checks.
          // copy the root diff, and then process any children it has
          ElementDefinition e = processPaths(indent+"  ", result, base, differential, baseCursor, ndc, nbl, ndl, url, webUrl, profileName+pathTail(diffMatches, 0), contextPathSrc, contextPathDst, 
              trimDifferential, contextName, resultPathBase, true, null, cpath, redirector, srcSD);
          if (e==null)
            throw new FHIRException(context.formatMessage(I18nConstants.DID_NOT_FIND_TYPE_ROOT_, diffMatches.get(0).getPath()));
          // now set up slicing on the e (cause it was wiped by what we called.
          e.setSlicing(new ElementDefinitionSlicingComponent());
          e.getSlicing().addDiscriminator().setType(DiscriminatorType.TYPE).setPath("$this");
          e.getSlicing().setRules(SlicingRules.CLOSED); // type slicing is always closed; the differential might call it open, but that just means it's not constraining the slices it doesn't mention
          e.getSlicing().setOrdered(false);
          start++;

          String fixedType = null;
          List<BaseTypeSlice> baseSlices = findBaseSlices(base, nbl);
          // now process the siblings, which should each be type constrained - and may also have their own children. they may match existing slices
          // now we process the base scope repeatedly for each instance of the item in the differential list
          for (int i = start; i < diffMatches.size(); i++) {
            String type = determineFixedType(diffMatches, fixedType, i);
            // our processing scope for the differential is the item in the list, and all the items before the next one in the list
            if (diffMatches.get(i).getMin() > 0) {
              if (diffMatches.size() > i+1) {
                throw new FHIRException(context.formatMessage(I18nConstants.INVALID_SLICING__THERE_IS_MORE_THAN_ONE_TYPE_SLICE_AT__BUT_ONE_OF_THEM__HAS_MIN__1_SO_THE_OTHER_SLICES_CANNOT_EXIST, diffMatches.get(i).getPath(), diffMatches.get(i).getSliceName()));
              }
              fixedType = type;
            }
            ndc = differential.getElement().indexOf(diffMatches.get(i));
            ndl = findEndOfElement(differential, ndc);
            int sStart = baseCursor;
            int sEnd = nbl;
            BaseTypeSlice bs = chooseMatchingBaseSlice(baseSlices, type);
            if (bs != null) {
              sStart = bs.start;
              sEnd = bs.end;
              bs.handled = true;
            }
            processPaths(indent+"  ", result, base, differential, sStart, ndc, sEnd, ndl, url, webUrl, profileName+pathTail(diffMatches, i), contextPathSrc, contextPathDst, trimDifferential, contextName, resultPathBase, true, e, cpath, redirector, srcSD);
          }
          if (elementToRemove != null) {
            differential.getElement().remove(elementToRemove);
            ndl--;
          }
          if (fixedType != null) {
            for (Iterator<TypeRefComponent> iter = e.getType().iterator(); iter.hasNext(); ) {
              TypeRefComponent tr = iter.next();
              if (!tr.getCode().equals(fixedType)) {
                iter.remove();
              }
            }
          }
          for (BaseTypeSlice bs : baseSlices) {
            if (!bs.handled) {
              // ok we gimme up a fake differential that says nothing, and run that against the slice.
              StructureDefinitionDifferentialComponent fakeDiff = new StructureDefinitionDifferentialComponent();
              fakeDiff.getElementFirstRep().setPath(bs.defn.getPath());
              processPaths(indent+"  ", result, base, fakeDiff, bs.start, 0, bs.end, 0, url, webUrl, profileName+tail(bs.defn.getPath()), contextPathSrc, contextPathDst, trimDifferential, contextName, resultPathBase, true, e, cpath, redirector, srcSD);
              
            }
          }
          // ok, done with that - next in the base list
          baseCursor = baseSlices.get(baseSlices.size()-1).end+1;
          diffCursor = ndl+1;
          //throw new Error("not done yet - slicing / types @ "+cpath);
        } else {
          // first - check that the slicing is ok
          boolean closed = currentBase.getSlicing().getRules() == SlicingRules.CLOSED;
          int diffpos = 0;
          boolean isExtension = cpath.endsWith(".extension") || cpath.endsWith(".modifierExtension");
          if (diffMatches.get(0).hasSlicing()) { // it might be null if the differential doesn't want to say anything about slicing
//            if (!isExtension)
//              diffpos++; // if there's a slice on the first, we'll ignore any content it has
            ElementDefinitionSlicingComponent dSlice = diffMatches.get(0).getSlicing();
            ElementDefinitionSlicingComponent bSlice = currentBase.getSlicing();
            if (dSlice.hasOrderedElement() && bSlice.hasOrderedElement() && !orderMatches(dSlice.getOrderedElement(), bSlice.getOrderedElement()))
              throw new DefinitionException(context.formatMessage(I18nConstants.SLICING_RULES_ON_DIFFERENTIAL__DO_NOT_MATCH_THOSE_ON_BASE___ORDER___, summarizeSlicing(dSlice), summarizeSlicing(bSlice), path, contextName));
            if (!discriminatorMatches(dSlice.getDiscriminator(), bSlice.getDiscriminator()))
              throw new DefinitionException(context.formatMessage(I18nConstants.SLICING_RULES_ON_DIFFERENTIAL__DO_NOT_MATCH_THOSE_ON_BASE___DISCIMINATOR___, summarizeSlicing(dSlice), summarizeSlicing(bSlice), path, contextName));
            if (!currentBase.isChoice() && !ruleMatches(dSlice.getRules(), bSlice.getRules()))
              throw new DefinitionException(context.formatMessage(I18nConstants.SLICING_RULES_ON_DIFFERENTIAL__DO_NOT_MATCH_THOSE_ON_BASE___RULE___, summarizeSlicing(dSlice), summarizeSlicing(bSlice), path, contextName));
          }
          ElementDefinition outcome = updateURLs(url, webUrl, currentBase.copy());
          outcome.setPath(fixedPathDest(contextPathDst, outcome.getPath(), redirector, contextPathSrc));
          updateFromBase(outcome, currentBase);
          if (diffMatches.get(0).hasSlicing() || !diffMatches.get(0).hasSliceName()) {
            updateFromSlicing(outcome.getSlicing(), diffMatches.get(0).getSlicing());
            updateFromDefinition(outcome, diffMatches.get(0), profileName, closed, url, srcSD); // if there's no slice, we don't want to update the unsliced description
            removeStatusExtensions(outcome);
          } else if (!diffMatches.get(0).hasSliceName()) {
            diffMatches.get(0).setUserData(GENERATED_IN_SNAPSHOT, outcome); // because of updateFromDefinition isn't called
          }
          
          result.getElement().add(outcome);

          if (!diffMatches.get(0).hasSliceName()) { // it's not real content, just the slice
            diffpos++; 
          }
          if (hasInnerDiffMatches(differential, cpath, diffCursor, diffLimit, base.getElement(), false)) {
            int nbl = findEndOfElement(base, baseCursor);
            int ndx = differential.getElement().indexOf(diffMatches.get(0));
            int ndc = ndx+(diffMatches.get(0).hasSlicing() ? 1 : 0);
            int ndl = findEndOfElement(differential, ndx);
            if (nbl == baseCursor) {
              if (base.getElement().get(baseCursor).getType().size() != 1) {
                throw new Error(context.formatMessage(I18nConstants.DIFFERENTIAL_WALKS_INTO____BUT_THE_BASE_DOES_NOT_AND_THERE_IS_NOT_A_SINGLE_FIXED_TYPE_THE_TYPE_IS__THIS_IS_NOT_HANDLED_YET, cpath, diffMatches.get(0).toString(), base.getElement().get(baseCursor).typeSummary()));
              }
              StructureDefinition dt = getProfileForDataType(base.getElement().get(baseCursor).getType().get(0));
              if (dt == null) {
                throw new DefinitionException(context.formatMessage(I18nConstants.UNKNOWN_TYPE__AT_, outcome.getType().get(0), diffMatches.get(0).getPath()));
              }
              contextName = dt.getUrl();
              while (differential.getElement().size() > diffCursor && pathStartsWith(differential.getElement().get(diffCursor).getPath(), cpath+"."))
                diffCursor++;
              processPaths(indent+"  ", result, dt.getSnapshot(), differential, 1, ndc, dt.getSnapshot().getElement().size()-1, ndl, 
                  url, getWebUrl(dt, webUrl, indent), profileName, cpath, outcome.getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirector, srcSD);
            } else {
              processPaths(indent+"  ", result, base, differential, baseCursor+1, ndc, nbl, ndl, 
                  url, webUrl, profileName+pathTail(diffMatches, 0), contextPathSrc, contextPathDst, trimDifferential, contextName, resultPathBase, false, null, null, null, srcSD);
            }
//            throw new Error("Not done yet");
//          } else if (currentBase.getType().get(0).getCode().equals("BackboneElement") && diffMatches.size() > 0 && diffMatches.get(0).hasSliceName()) {
          } else if (currentBase.getType().get(0).getCode().equals("BackboneElement")) {
            // We need to copy children of the backbone element before we start messing around with slices
            int nbl = findEndOfElement(base, baseCursor);
            for (int i = baseCursor+1; i<=nbl; i++) {
              outcome = updateURLs(url, webUrl, base.getElement().get(i).copy());
              result.getElement().add(outcome);
            }
          }

          // now, we have two lists, base and diff. we're going to work through base, looking for matches in diff.
          List<ElementDefinition> baseMatches = getSiblings(base.getElement(), currentBase);
          for (ElementDefinition baseItem : baseMatches) {
            baseCursor = base.getElement().indexOf(baseItem);
            outcome = updateURLs(url, webUrl, baseItem.copy());
            updateFromBase(outcome, currentBase);
            outcome.setPath(fixedPathDest(contextPathDst, outcome.getPath(), redirector, contextPathSrc));
            outcome.setSlicing(null);
            if (!outcome.getPath().startsWith(resultPathBase))
              throw new DefinitionException(context.formatMessage(I18nConstants.ADDING_WRONG_PATH));
            if (diffpos < diffMatches.size() && diffMatches.get(diffpos).hasSliceName() && diffMatches.get(diffpos).getSliceName().equals(outcome.getSliceName())) {
              // if there's a diff, we update the outcome with diff
              // no? updateFromDefinition(outcome, diffMatches.get(diffpos), profileName, closed, url);
              //then process any children
              int nbl = findEndOfElement(base, baseCursor);
              int ndc = differential.getElement().indexOf(diffMatches.get(diffpos));
              int ndl = findEndOfElement(differential, ndc);
              // now we process the base scope repeatedly for each instance of the item in the differential list
              processPaths(indent+"  ", result, base, differential, baseCursor, ndc, nbl, ndl, url, webUrl, profileName+pathTail(diffMatches, diffpos), contextPathSrc, contextPathDst, closed, contextName, resultPathBase, true, null, null, redirector, srcSD);
              // ok, done with that - now set the cursors for if this is the end
              baseCursor = nbl;
              diffCursor = ndl+1;
              diffpos++;
            } else {
              result.getElement().add(outcome);
              baseCursor++;
              // just copy any children on the base
              while (baseCursor < base.getElement().size() && base.getElement().get(baseCursor).getPath().startsWith(path) && !base.getElement().get(baseCursor).getPath().equals(path)) {
                outcome = updateURLs(url, webUrl, base.getElement().get(baseCursor).copy());
                outcome.setPath(fixedPathDest(contextPathDst, outcome.getPath(), redirector, contextPathSrc));
                if (!outcome.getPath().startsWith(resultPathBase))
                  throw new DefinitionException(context.formatMessage(I18nConstants.ADDING_WRONG_PATH));
                result.getElement().add(outcome);
                baseCursor++;
              }
              //Lloyd - add this for test T15
              baseCursor--;
            }
          }
          // finally, we process any remaining entries in diff, which are new (and which are only allowed if the base wasn't closed
          boolean checkImplicitTypes = false;
          if (closed && diffpos < diffMatches.size()) {
            // this is a problem, unless we're on a polymorhpic type and we're going to constrain a slice that actually implicitly exists
            if (currentBase.getPath().endsWith("[x]")) {
              checkImplicitTypes = true;
            } else {
              throw new DefinitionException(context.formatMessage(I18nConstants.THE_BASE_SNAPSHOT_MARKS_A_SLICING_AS_CLOSED_BUT_THE_DIFFERENTIAL_TRIES_TO_EXTEND_IT_IN__AT__, profileName, path, cpath));
            }
          } 
          if (diffpos == diffMatches.size()) {
//Lloyd This was causing problems w/ Telus
//            diffCursor++;
          } else {
            while (diffpos < diffMatches.size()) {
              ElementDefinition diffItem = diffMatches.get(diffpos);
              for (ElementDefinition baseItem : baseMatches)
                if (baseItem.getSliceName().equals(diffItem.getSliceName()))
                  throw new DefinitionException(context.formatMessage(I18nConstants.NAMED_ITEMS_ARE_OUT_OF_ORDER_IN_THE_SLICE));
              outcome = updateURLs(url, webUrl, currentBase.copy());
              //            outcome = updateURLs(url, diffItem.copy());
              outcome.setPath(fixedPathDest(contextPathDst, outcome.getPath(), redirector, contextPathSrc));
              updateFromBase(outcome, currentBase);
              outcome.setSlicing(null);
              outcome.setMin(0); // we're in a slice, so it's only a mandatory if it's explicitly marked so
              if (!outcome.getPath().startsWith(resultPathBase))
                throw new DefinitionException(context.formatMessage(I18nConstants.ADDING_WRONG_PATH));
              result.getElement().add(outcome);
              updateFromDefinition(outcome, diffItem, profileName, trimDifferential, url, srcSD);
              removeStatusExtensions(outcome);
              // --- LM Added this
              diffCursor = differential.getElement().indexOf(diffItem)+1;
              if (!outcome.getType().isEmpty() && (/*outcome.getType().get(0).getCode().equals("Extension") || */differential.getElement().size() > diffCursor) && outcome.getPath().contains(".")/* && isDataType(outcome.getType())*/) {  // don't want to do this for the root, since that's base, and we're already processing it
                if (!baseWalksInto(base.getElement(), baseCursor)) {
                  if (differential.getElement().size() > diffCursor && pathStartsWith(differential.getElement().get(diffCursor).getPath(), diffMatches.get(0).getPath()+".")) {
                    if (outcome.getType().size() > 1)
                      for (TypeRefComponent t : outcome.getType()) {
                        if (!t.getCode().equals("Reference"))
                          throw new DefinitionException(context.formatMessage(I18nConstants._HAS_CHILDREN__AND_MULTIPLE_TYPES__IN_PROFILE_, diffMatches.get(0).getPath(), differential.getElement().get(diffCursor).getPath(), typeCode(outcome.getType()), profileName));
                      }
                    TypeRefComponent t = outcome.getType().get(0);
                    if (t.getCode().equals("BackboneElement")) {
                      int baseStart = base.getElement().indexOf(currentBase)+1;
                      int baseMax = baseStart + 1;
                      while (baseMax < base.getElement().size() && base.getElement().get(baseMax).getPath().startsWith(currentBase.getPath()+"."))
                       baseMax++;
                      int start = diffCursor;
                      while (differential.getElement().size() > diffCursor && pathStartsWith(differential.getElement().get(diffCursor).getPath(), diffMatches.get(0).getPath()+"."))
                        diffCursor++;
                      processPaths(indent+"  ", result, base, differential, baseStart, start-1, baseMax-1,
                          diffCursor - 1, url, webUrl, profileName+pathTail(diffMatches, 0), base.getElement().get(0).getPath(), base.getElement().get(0).getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirector, srcSD);
                      
                    } else {
                      StructureDefinition dt = getProfileForDataType(outcome.getType().get(0));
                      //                if (t.getCode().equals("Extension") && t.hasProfile() && !t.getProfile().contains(":")) {
                      // lloydfix                  dt =
                      //                }
                      if (dt == null)
                        throw new DefinitionException(context.formatMessage(I18nConstants._HAS_CHILDREN__FOR_TYPE__IN_PROFILE__BUT_CANT_FIND_TYPE, diffMatches.get(0).getPath(), differential.getElement().get(diffCursor).getPath(), typeCode(outcome.getType()), profileName));
                      contextName = dt.getUrl();
                      int start = diffCursor;
                      while (differential.getElement().size() > diffCursor && pathStartsWith(differential.getElement().get(diffCursor).getPath(), diffMatches.get(0).getPath()+"."))
                        diffCursor++;
                      processPaths(indent+"  ", result, dt.getSnapshot(), differential, 1 /* starting again on the data type, but skip the root */, start-1, dt.getSnapshot().getElement().size()-1,
                          diffCursor - 1, url, getWebUrl(dt, webUrl, indent), profileName+pathTail(diffMatches, 0), diffMatches.get(0).getPath(), outcome.getPath(), trimDifferential, contextName, resultPathBase, false, null, null, redirector, srcSD);
                    }
                  }
                }
              }
              // ---
              diffpos++;
            }
          }
          baseCursor++;
        }
      }
    }
    
    int i = 0;
    for (ElementDefinition e : result.getElement()) {
      i++;
      if (e.hasMinElement() && e.getMinElement().getValue()==null)
        throw new Error(context.formatMessage(I18nConstants.NULL_MIN));
    }
    return res;
  }

  private Set<String> getListOfTypes(ElementDefinition e) {
    Set<String> result = new HashSet<>();
    for (TypeRefComponent t : e.getType()) {
      result.add(t.getCode());
    }
    return result;
  }

  public StructureDefinition getTypeForElement(StructureDefinitionDifferentialComponent differential, int diffCursor, String profileName,
      List<ElementDefinition> diffMatches, ElementDefinition outcome) {
    if (outcome.getType().size() == 0) {
      throw new DefinitionException(context.formatMessage(I18nConstants._HAS_NO_CHILDREN__AND_NO_TYPES_IN_PROFILE_, diffMatches.get(0).getPath(), differential.getElement().get(diffCursor).getPath(), profileName));
    }
    if (outcome.getType().size() > 1) {
      for (TypeRefComponent t : outcome.getType()) {
        if (!t.getWorkingCode().equals("Reference"))
          throw new DefinitionException(context.formatMessage(I18nConstants._HAS_CHILDREN__AND_MULTIPLE_TYPES__IN_PROFILE_, diffMatches.get(0).getPath(), differential.getElement().get(diffCursor).getPath(), typeCode(outcome.getType()), profileName));
      }
    }
    StructureDefinition dt = getProfileForDataType(outcome.getType().get(0));
    if (dt == null)
      throw new DefinitionException(context.formatMessage(I18nConstants.UNKNOWN_TYPE__AT_, outcome.getType().get(0), diffMatches.get(0).getPath()));
    return dt;
  }

  private String sliceNames(List<ElementDefinition> diffMatches) {
    CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder();
    for (ElementDefinition ed : diffMatches) {
      if (ed.hasSliceName()) {
        b.append(ed.getSliceName());
      }
    }
    return b.toString();
  }

  private boolean isMatchingType(StructureDefinition sd, List<TypeRefComponent> types, String inner) {
    while (sd != null) {
      for (TypeRefComponent tr : types) {
        if (sd.getUrl().startsWith("http://hl7.org/fhir/StructureDefinition") && sd.getType().equals(tr.getCode())) {
          return true;
        }
        if (inner == null && sd.getUrl().equals(tr.getCode())) {
          return true;
        }
        if (inner != null) {
          ElementDefinition ed = null;
          for (ElementDefinition t : sd.getSnapshot().getElement()) {
            if (inner.equals(t.getId())) {
              ed = t;
            }
          }
          if (ed != null) {
            return isMatchingType(ed.getType(), types);
          }
        }
      }
      sd = context.fetchResource(StructureDefinition.class, sd.getBaseDefinition());    
    }
    return false;
  }

  private boolean isMatchingType(List<TypeRefComponent> test, List<TypeRefComponent> desired) {
    for (TypeRefComponent t : test) {
      for (TypeRefComponent d : desired) {
        if (t.getCode().equals(d.getCode())) {
          return true;          
        }
      }
    }
    return false;
  }

  private boolean isValidType(TypeRefComponent t, ElementDefinition base) {
    for (TypeRefComponent tr : base.getType()) {
      if (tr.getCode().equals(t.getCode())) {
        return true;
      }
      if (tr.getWorkingCode().equals(t.getCode())) {
        System.out.println("Type error: use of a simple type \""+t.getCode()+"\" wrongly constraining "+base.getPath());
        return true;
      }
    }
    return false;
  }

  private boolean isGenerating(StructureDefinition sd) {
    return sd.hasUserData("profileutils.snapshot.generating");
  }


  private void checkNotGenerating(StructureDefinition sd, String role) {
    if (sd.hasUserData("profileutils.snapshot.generating")) {
      throw new FHIRException(context.formatMessage(I18nConstants.ATTEMPT_TO_USE_A_SNAPSHOT_ON_PROFILE__AS__BEFORE_IT_IS_GENERATED, sd.getUrl(), role));
    }
  }

  private boolean isBaseResource(List<TypeRefComponent> types) {
    if (types.isEmpty())
      return false;
    for (TypeRefComponent type : types) {
      String t = type.getWorkingCode();
      if ("Resource".equals(t))
        return false;
    }
    return true;
    
  }

  public String determineFixedType(List<ElementDefinition> diffMatches, String fixedType, int i) {
    if (diffMatches.get(i).getType().size() == 0 && diffMatches.get(i).hasSliceName()) {
      String n = tail(diffMatches.get(i).getPath()).replace("[x]", "");
      String t = diffMatches.get(i).getSliceName().substring(n.length());
      if (isDataType(t)) {
        fixedType = t;
      } else if (isPrimitive(Utilities.uncapitalize(t))) {
        fixedType = Utilities.uncapitalize(t);
      } else {
        throw new FHIRException(context.formatMessage(I18nConstants.UNEXPECTED_CONDITION_IN_DIFFERENTIAL_TYPESLICETYPELISTSIZE__10_AND_IMPLICIT_SLICE_NAME_DOES_NOT_CONTAIN_A_VALID_TYPE__AT_, t, diffMatches.get(i).getPath(), diffMatches.get(i).getSliceName()));
      }                
    } else if (diffMatches.get(i).getType().size() == 1) {
      fixedType = diffMatches.get(i).getType().get(0).getCode();
    } else {
      throw new FHIRException(context.formatMessage(I18nConstants.UNEXPECTED_CONDITION_IN_DIFFERENTIAL_TYPESLICETYPELISTSIZE__1_AT_, diffMatches.get(i).getPath(), diffMatches.get(i).getSliceName()));
    }
    return fixedType;
  }


  private BaseTypeSlice chooseMatchingBaseSlice(List<BaseTypeSlice> baseSlices, String type) {
    for (BaseTypeSlice bs : baseSlices) {
      if (bs.type.equals(type)) {
        return bs;
      }
    }
    return null;
  }


  private List<BaseTypeSlice> findBaseSlices(StructureDefinitionSnapshotComponent list, int start) {
    List<BaseTypeSlice> res = new ArrayList<>();
    ElementDefinition base = list.getElement().get(start);
    int i = start + 1;
    while (i <  list.getElement().size() && list.getElement().get(i).getPath().startsWith(base.getPath()+".")) {
      i++;      
    };
    while (i <  list.getElement().size() && list.getElement().get(i).getPath().equals(base.getPath()) && list.getElement().get(i).hasSliceName()) {
      int s = i;
      i++;
      while (i <  list.getElement().size() && list.getElement().get(i).getPath().startsWith(base.getPath()+".")) {
        i++;      
      };
      res.add(new BaseTypeSlice(list.getElement().get(s), list.getElement().get(s).getTypeFirstRep().getCode(), s, i-1));
    }
    return res;
  }


  private String getWebUrl(StructureDefinition dt, String webUrl, String indent) {
    if (dt.hasUserData("path")) {
      // this is a hack, but it works for now, since we don't have deep folders
      String url = dt.getUserString("path");
      int i = url.lastIndexOf("/");
      if (i < 1) {
        return defWebRoot;
      } else {
        return url.substring(0, i+1);
      }
    } else {  
      return webUrl;
    }
  }

  private void removeStatusExtensions(ElementDefinition outcome) {
    outcome.removeExtension(ToolingExtensions.EXT_FMM_LEVEL);
    outcome.removeExtension(ToolingExtensions.EXT_FMM_SUPPORT);
    outcome.removeExtension(ToolingExtensions.EXT_FMM_DERIVED);
    outcome.removeExtension(ToolingExtensions.EXT_STANDARDS_STATUS);
    outcome.removeExtension(ToolingExtensions.EXT_NORMATIVE_VERSION);
    outcome.removeExtension(ToolingExtensions.EXT_WORKGROUP);    
    outcome.removeExtension(ToolingExtensions.EXT_FMM_SUPPORT);
    outcome.removeExtension(ToolingExtensions.EXT_FMM_DERIVED);
  }

  private String descED(List<ElementDefinition> list, int index) {
    return index >=0 && index < list.size() ? list.get(index).present() : "X";
  }

  private boolean baseHasChildren(StructureDefinitionSnapshotComponent base, ElementDefinition ed) {
    int index = base.getElement().indexOf(ed);
    if (index == -1 || index >= base.getElement().size()-1)
      return false;
    String p = base.getElement().get(index+1).getPath();
    return isChildOf(p, ed.getPath());
  }


  private boolean isChildOf(String sub, String focus) {
    if (focus.endsWith("[x]")) {
      focus = focus.substring(0, focus.length()-3);
      return sub.startsWith(focus);
    } else 
      return sub.startsWith(focus+".");
  }


  private int indexOfFirstNonChild(StructureDefinitionSnapshotComponent base, ElementDefinition currentBase, int i, int baseLimit) {
    return baseLimit+1;
  }


  private String rootName(String cpath) {
    String t = tail(cpath);
    return t.replace("[x]", "");
  }


  private String determineTypeSlicePath(String path, String cpath) {
    String headP = path.substring(0, path.lastIndexOf("."));
//    String tailP = path.substring(path.lastIndexOf(".")+1);
    String tailC = cpath.substring(cpath.lastIndexOf(".")+1);
    return headP+"."+tailC;
  }


  private boolean isImplicitSlicing(ElementDefinition ed, String path) {
    if (ed == null || ed.getPath() == null || path == null)
      return false;
    if (path.equals(ed.getPath()))
      return false;
    boolean ok = path.endsWith("[x]") && ed.getPath().startsWith(path.substring(0, path.length()-3));
    return ok;
  }


  private boolean diffsConstrainTypes(List<ElementDefinition> diffMatches, String cPath, List<TypeSlice> typeList) {
//    if (diffMatches.size() < 2)
    //      return false;
    String p = diffMatches.get(0).getPath();
    if (!p.endsWith("[x]") && !cPath.endsWith("[x]"))
      return false;
    typeList.clear();
    String rn = tail(cPath);
    rn = rn.substring(0, rn.length()-3);
    for (int i = 0; i < diffMatches.size(); i++) {
      ElementDefinition ed = diffMatches.get(i);
      String n = tail(ed.getPath());
      if (!n.startsWith(rn))
        return false;
      String s = n.substring(rn.length());
      if (!s.contains(".")) {
        if (ed.hasSliceName() && ed.getType().size() == 1) {
          typeList.add(new TypeSlice(ed, ed.getTypeFirstRep().getWorkingCode()));
        } else if (ed.hasSliceName() && ed.getType().size() == 0) {
          if (isDataType(s)) {
            typeList.add(new TypeSlice(ed, s));
          } else if (isPrimitive(Utilities.uncapitalize(s))) {
            typeList.add(new TypeSlice(ed, Utilities.uncapitalize(s)));
          } else {
            String tn = ed.getSliceName().substring(n.length());
            if (isDataType(tn)) {
              typeList.add(new TypeSlice(ed, tn));
            } else if (isPrimitive(Utilities.uncapitalize(tn))) {
              typeList.add(new TypeSlice(ed, Utilities.uncapitalize(tn)));
            }
          }
        } else if (!ed.hasSliceName() && !s.equals("[x]")) {
          if (isDataType(s))
            typeList.add(new TypeSlice(ed, s));
          else if (isConstrainedDataType(s))
            typeList.add(new TypeSlice(ed, baseType(s)));
          else if (isPrimitive(Utilities.uncapitalize(s)))
            typeList.add(new TypeSlice(ed, Utilities.uncapitalize(s)));
        } else if (!ed.hasSliceName() && s.equals("[x]"))
            typeList.add(new TypeSlice(ed, null));
          }
        }
    return true;
  }


  private List<ElementRedirection> redirectorStack(List<ElementRedirection> redirector, ElementDefinition outcome, String path) {
    List<ElementRedirection> result = new ArrayList<ElementRedirection>();
    result.addAll(redirector);
    result.add(new ElementRedirection(outcome, path));
    return result;
  }


  private List<TypeRefComponent> getByTypeName(List<TypeRefComponent> type, String t) {
    List<TypeRefComponent> res = new ArrayList<TypeRefComponent>();
    for (TypeRefComponent tr : type) {
      if (t.equals(tr.getWorkingCode()))
          res.add(tr);
    }
    return res;
  }


  private void replaceFromContentReference(ElementDefinition outcome, ElementDefinition tgt) {
    outcome.setContentReference(null);
    outcome.getType().clear(); // though it should be clear anyway
    outcome.getType().addAll(tgt.getType());    
  }


  private boolean baseWalksInto(List<ElementDefinition> elements, int cursor) {
    if (cursor >= elements.size())
      return false;
    String path = elements.get(cursor).getPath();
    String prevPath = elements.get(cursor - 1).getPath();
    return path.startsWith(prevPath + ".");
  }


  private ElementDefinition fillOutFromBase(ElementDefinition profile, ElementDefinition usage) throws FHIRFormatError {
    ElementDefinition res = profile.copy();
    if (!res.hasSliceName())
      res.setSliceName(usage.getSliceName());
    if (!res.hasLabel())
      res.setLabel(usage.getLabel());
    for (Coding c : usage.getCode())
      if (!res.hasCode(c))
        res.addCode(c);
    
    if (!res.hasDefinition())
      res.setDefinition(usage.getDefinition());
    if (!res.hasShort() && usage.hasShort())
      res.setShort(usage.getShort());
    if (!res.hasComment() && usage.hasComment())
      res.setComment(usage.getComment());
    if (!res.hasRequirements() && usage.hasRequirements())
      res.setRequirements(usage.getRequirements());
    for (StringType c : usage.getAlias())
      if (!res.hasAlias(c.getValue()))
        res.addAlias(c.getValue());
    if (!res.hasMin() && usage.hasMin())
      res.setMin(usage.getMin());
    if (!res.hasMax() && usage.hasMax())
      res.setMax(usage.getMax());
     
    if (!res.hasFixed() && usage.hasFixed())
      res.setFixed(usage.getFixed());
    if (!res.hasPattern() && usage.hasPattern())
      res.setPattern(usage.getPattern());
    if (!res.hasExample() && usage.hasExample())
      res.setExample(usage.getExample());
    if (!res.hasMinValue() && usage.hasMinValue())
      res.setMinValue(usage.getMinValue());
    if (!res.hasMaxValue() && usage.hasMaxValue())
      res.setMaxValue(usage.getMaxValue());     
    if (!res.hasMaxLength() && usage.hasMaxLength())
      res.setMaxLength(usage.getMaxLength());
    if (!res.hasMustSupport() && usage.hasMustSupport())
      res.setMustSupport(usage.getMustSupport());
    if (!res.hasBinding() && usage.hasBinding())
      res.setBinding(usage.getBinding().copy());
    for (ElementDefinitionConstraintComponent c : usage.getConstraint())
      if (!res.hasConstraint(c.getKey()))
        res.addConstraint(c);
    for (Extension e : usage.getExtension()) {
      if (!res.hasExtension(e.getUrl()))
        res.addExtension(e.copy());
    }
    
    return res;
  }


  private boolean checkExtensionDoco(ElementDefinition base) {
    // see task 3970. For an extension, there's no point copying across all the underlying definitional stuff
    boolean isExtension = (base.getPath().equals("Extension") || base.getPath().endsWith(".extension") || base.getPath().endsWith(".modifierExtension")) &&
          (!base.hasBase() || !"II.extension".equals(base.getBase().getPath()));
    if (isExtension) {
      base.setDefinition("An Extension");
      base.setShort("Extension");
      base.setCommentElement(null);
      base.setRequirementsElement(null);
      base.getAlias().clear();
      base.getMapping().clear();
    }
    return isExtension;
  }


  private String pathTail(List<ElementDefinition> diffMatches, int i) {
    
    ElementDefinition d = diffMatches.get(i);
    String s = d.getPath().contains(".") ? d.getPath().substring(d.getPath().lastIndexOf(".")+1) : d.getPath();
    return "."+s + (d.hasType() && d.getType().get(0).hasProfile() ? "["+d.getType().get(0).getProfile()+"]" : "");
  }


  private void markDerived(ElementDefinition outcome) {
    for (ElementDefinitionConstraintComponent inv : outcome.getConstraint())
      inv.setUserData(IS_DERIVED, true);
  }


  public static String summarizeSlicing(ElementDefinitionSlicingComponent slice) {
    StringBuilder b = new StringBuilder();
    boolean first = true;
    for (ElementDefinitionSlicingDiscriminatorComponent d : slice.getDiscriminator()) {
      if (first)
        first = false;
      else
        b.append(", ");
      b.append(d.getType().toCode()+":"+d.getPath());
    }
    b.append(" (");
    if (slice.hasOrdered())
      b.append(slice.getOrdered() ? "ordered" : "unordered");
    b.append("/");
    if (slice.hasRules())
      b.append(slice.getRules().toCode());
    b.append(")");
    if (slice.hasDescription()) {
      b.append(" \"");
      b.append(slice.getDescription());
      b.append("\"");
    }
    return b.toString();
  }


  private void updateFromBase(ElementDefinition derived, ElementDefinition base) {
    if (base.hasBase()) {
      if (!derived.hasBase())
        derived.setBase(new ElementDefinitionBaseComponent());
      derived.getBase().setPath(base.getBase().getPath());
      derived.getBase().setMin(base.getBase().getMin());
      derived.getBase().setMax(base.getBase().getMax());
    } else {
      if (!derived.hasBase())
        derived.setBase(new ElementDefinitionBaseComponent());
      derived.getBase().setPath(base.getPath());
      derived.getBase().setMin(base.getMin());
      derived.getBase().setMax(base.getMax());
    }
  }


  private boolean pathStartsWith(String p1, String p2) {
    return p1.startsWith(p2) || (p2.endsWith("[x].") && p1.startsWith(p2.substring(0, p2.length()-4)));
  }

  private boolean pathMatches(String p1, String p2) {
    return p1.equals(p2) || (p2.endsWith("[x]") && p1.startsWith(p2.substring(0, p2.length()-3)) && !p1.substring(p2.length()-3).contains("."));
  }


  private String fixedPathSource(String contextPath, String pathSimple, List<ElementRedirection> redirector) {
    if (contextPath == null)
      return pathSimple;
//    String ptail = pathSimple.substring(contextPath.length() + 1);
    if (redirector.size() > 0) {
      String ptail = null;
      if (contextPath.length() >= pathSimple.length()) {
        ptail = pathSimple.substring(pathSimple.indexOf(".")+1);
      } else {
        ptail = pathSimple.substring(contextPath.length()+1);
      }
      return redirector.get(redirector.size()-1).getPath()+"."+ptail;
//      return contextPath+"."+tail(redirector.getPath())+"."+ptail.substring(ptail.indexOf(".")+1);
    } else {
      String ptail = pathSimple.substring(pathSimple.indexOf(".")+1);
      return contextPath+"."+ptail;
    }
  }
  
  private String fixedPathDest(String contextPath, String pathSimple, List<ElementRedirection> redirector, String redirectSource) {
    String s;
    if (contextPath == null)
      s = pathSimple;
    else {
      if (redirector.size() > 0) {
        String ptail = null;
        if (redirectSource.length() >= pathSimple.length()) {
          ptail = pathSimple.substring(pathSimple.indexOf(".")+1);
        } else {
          ptail = pathSimple.substring(redirectSource.length()+1);
        }
  //      ptail = ptail.substring(ptail.indexOf(".")+1);
        s = contextPath+"."+/*tail(redirector.getPath())+"."+*/ptail;
      } else {
        String ptail = pathSimple.substring(pathSimple.indexOf(".")+1);
        s = contextPath+"."+ptail;
      }
    }
    return s;
  }  

  private StructureDefinition getProfileForDataType(TypeRefComponent type)  {
    StructureDefinition sd = null;
    if (type.hasProfile()) {
      sd = context.fetchResource(StructureDefinition.class, type.getProfile().get(0).getValue());
      if (sd == null)
        System.out.println("Failed to find referenced profile: " + type.getProfile());
    }
    if (sd == null)
      sd = context.fetchTypeDefinition(type.getWorkingCode());
    if (sd == null)
      System.out.println("XX: failed to find profle for type: " + type.getWorkingCode()); // debug GJM
    return sd;
  }

  private StructureDefinition getProfileForDataType(String type)  {
    StructureDefinition sd = context.fetchTypeDefinition(type);
    if (sd == null)
      System.out.println("XX: failed to find profle for type: " + type); // debug GJM
    return sd;
  }


  public static String typeCode(List<TypeRefComponent> types) {
    StringBuilder b = new StringBuilder();
    boolean first = true;
    for (TypeRefComponent type : types) {
      if (first) first = false; else b.append(", ");
      b.append(type.getWorkingCode());
      if (type.hasTargetProfile())
        b.append("{"+type.getTargetProfile()+"}");
      else if (type.hasProfile())
        b.append("{"+type.getProfile()+"}");
    }
    return b.toString();
  }


  private boolean isDataType(List<TypeRefComponent> types) {
    if (types.isEmpty())
      return false;
    for (TypeRefComponent type : types) {
      String t = type.getWorkingCode();
      if (!isDataType(t) && !isPrimitive(t))
        return false;
    }
    return true;
  }


  /**
   * Finds internal references in an Element's Binding and StructureDefinition references (in TypeRef) and bases them on the given url
   * @param url - the base url to use to turn internal references into absolute references
   * @param element - the Element to update
   * @return - the updated Element
   */
  private ElementDefinition updateURLs(String url, String webUrl, ElementDefinition element) {
    if (element != null) {
      ElementDefinition defn = element;
      if (defn.hasBinding() && defn.getBinding().hasValueSet() && defn.getBinding().getValueSet().startsWith("#"))
        defn.getBinding().setValueSet(url+defn.getBinding().getValueSet());
      for (TypeRefComponent t : defn.getType()) {
        for (UriType u : t.getProfile()) {
          if (u.getValue().startsWith("#"))
            u.setValue(url+t.getProfile());
        }
        for (UriType u : t.getTargetProfile()) {
          if (u.getValue().startsWith("#"))
            u.setValue(url+t.getTargetProfile());
        }
      }
      if (webUrl != null) {
        // also, must touch up the markdown
        if (element.hasDefinition())
          element.setDefinition(processRelativeUrls(element.getDefinition(), webUrl, baseSpecUrl(), context.getResourceNames(), masterSourceFileNames, true));
        if (element.hasComment())
          element.setComment(processRelativeUrls(element.getComment(), webUrl, baseSpecUrl(), context.getResourceNames(), masterSourceFileNames, true));
        if (element.hasRequirements())
          element.setRequirements(processRelativeUrls(element.getRequirements(), webUrl, baseSpecUrl(), context.getResourceNames(), masterSourceFileNames, true));
        if (element.hasMeaningWhenMissing())
          element.setMeaningWhenMissing(processRelativeUrls(element.getMeaningWhenMissing(), webUrl, baseSpecUrl(), context.getResourceNames(), masterSourceFileNames, true));
      }
    }
    return element;
  }

  public static String processRelativeUrls(String markdown, String webUrl, String basePath, List<String> resourceNames, Set<String> filenames, boolean processRelatives) {
    StringBuilder b = new StringBuilder();
    int i = 0;
    while (i < markdown.length()) {
      if (i < markdown.length()-3 && markdown.substring(i, i+2).equals("](")) {
        int j = i + 2;
        while (j < markdown.length() && markdown.charAt(j) != ')')
          j++;
        if (j < markdown.length()) {
          String url = markdown.substring(i+2, j);
          if (!Utilities.isAbsoluteUrl(url) && !url.startsWith("..")) {
            // 
            // In principle, relative URLs are supposed to be converted to absolute URLs in snapshots. 
            // that's what this code is doing. 
            // 
            // But that hasn't always happened and there's packages out there where the snapshots 
            // contain relative references that actually are references to the main specification 
            // 
            // This code is trying to guess which relative references are actually to the
            // base specification.
            // 
            if (isLikelySourceURLReference(url, resourceNames, filenames)) {
              b.append("](");
              b.append(basePath);
              i = i + 1;
            } else {
              b.append("](");
              // disabled 7-Dec 2021 GDG - we don't want to fool with relative URLs at all? 
              // re-enabled 11-Feb 2022 GDG - we do want to do this. At least, $assemble in davinci-dtr, where the markdown comes from the SDC IG, and an SDC local reference must be changed to point to SDC. in this case, it's called when generating snapshots
              // added processRelatives parameter to deal with this (well, to try)
              if (processRelatives && webUrl != null) {
//                System.out.println("Making "+url+" relative to '"+webUrl+"'");
                b.append(webUrl);
              } else {
//                System.out.println("Not making "+url+" relative to '"+webUrl+"'");
              }
              i = i + 1;
            }
          } else
            b.append(markdown.charAt(i));
        } else 
          b.append(markdown.charAt(i));
      } else {
        b.append(markdown.charAt(i));
      }
      i++;
    }
    return b.toString();
  }


  public static boolean isLikelySourceURLReference(String url, List<String> resourceNames, Set<String> filenames) {
    if (resourceNames != null) {
      for (String n : resourceNames) {
        if (url.startsWith(n.toLowerCase()+".html")) {
          return true;
        }
        if (url.startsWith(n.toLowerCase()+"-definitions.html")) {
          return true;
        }
      }
    }
    if (filenames != null) {
      for (String n : filenames) {
        if (url.startsWith(n.toLowerCase())) {
          return true;
        }
      }
    }
    return 
        url.startsWith("extensibility.html") || 
        url.startsWith("terminologies.html") || 
        url.startsWith("observation.html") || 
        url.startsWith("codesystem.html") || 
        url.startsWith("fhirpath.html") || 
        url.startsWith("datatypes.html") || 
        url.startsWith("operations.html") || 
        url.startsWith("resource.html") || 
        url.startsWith("elementdefinition.html") ||
        url.startsWith("element-definitions.html") ||
        url.startsWith("snomedct.html") ||
        url.startsWith("loinc.html") ||
        url.startsWith("http.html") ||
        url.startsWith("references") ||
        url.startsWith("narrative.html") || 
        url.startsWith("search.html") ||
        url.startsWith("patient-operation-match.html") ||
        (url.startsWith("extension-") && url.contains(".html")) || 
        url.startsWith("resource-definitions.html");
  }

  private String baseSpecUrl() {
    if (VersionUtilities.isR5Ver(context.getVersion())) {
      return "http://build.fhir.org/";
    }
    if (VersionUtilities.isR4Ver(context.getVersion())) {
      return "http://hl7.org/fhir/R4/";
    }
    if (VersionUtilities.isR3Ver(context.getVersion())) {
      return "http://hl7.org/fhir/STU3/";
    }
    if (VersionUtilities.isR2BVer(context.getVersion())) {
      return "http://hl7.org/fhir/2016May/";
    }
    if (VersionUtilities.isR2Ver(context.getVersion())) {
      return "http://hl7.org/fhir/DSTU2/";
    }
    if (VersionUtilities.isR4BVer(context.getVersion())) {
      return "http://hl7.org/fhir/2021Mar/";
    }
    return "";
  }

  private List<ElementDefinition> getSiblings(List<ElementDefinition> list, ElementDefinition current) {
    List<ElementDefinition> result = new ArrayList<ElementDefinition>();
    String path = current.getPath();
    int cursor = list.indexOf(current)+1;
    while (cursor < list.size() && list.get(cursor).getPath().length() >= path.length()) {
      if (pathMatches(list.get(cursor).getPath(), path))
        result.add(list.get(cursor));
      cursor++;
    }
    return result;
  }

  private void updateFromSlicing(ElementDefinitionSlicingComponent dst, ElementDefinitionSlicingComponent src) {
    if (src.hasOrderedElement())
      dst.setOrderedElement(src.getOrderedElement().copy());
    if (src.hasDiscriminator()) {
      //    dst.getDiscriminator().addAll(src.getDiscriminator());  Can't use addAll because it uses object equality, not string equality
      for (ElementDefinitionSlicingDiscriminatorComponent s : src.getDiscriminator()) {
        boolean found = false;
        for (ElementDefinitionSlicingDiscriminatorComponent d : dst.getDiscriminator()) {
          if (matches(d, s)) {
            found = true;
            break;
          }
        }
        if (!found)
          dst.getDiscriminator().add(s);
      }
    }
    if (src.hasRulesElement())
      dst.setRulesElement(src.getRulesElement().copy());
  }

  private boolean orderMatches(BooleanType diff, BooleanType base) {
    return (diff == null) || (base == null) || (diff.getValue() == base.getValue());
  }

  private boolean discriminatorMatches(List<ElementDefinitionSlicingDiscriminatorComponent> diff, List<ElementDefinitionSlicingDiscriminatorComponent> base) {
    if (diff.isEmpty() || base.isEmpty())
        return true;
    if (diff.size() != base.size())
        return false;
    for (int i = 0; i < diff.size(); i++)
        if (!matches(diff.get(i), base.get(i)))
                return false;
    return true;
  }

  private boolean matches(ElementDefinitionSlicingDiscriminatorComponent c1, ElementDefinitionSlicingDiscriminatorComponent c2) {
    return c1.getType().equals(c2.getType()) && c1.getPath().equals(c2.getPath());
  }


  private boolean ruleMatches(SlicingRules diff, SlicingRules base) {
    return (diff == null) || (base == null) || (diff == base) || (base == SlicingRules.OPEN) ||
        ((diff == SlicingRules.OPENATEND && base == SlicingRules.CLOSED));
  }

  private boolean isSlicedToOneOnly(ElementDefinition e) {
    return (e.hasSlicing() && e.hasMaxElement() && e.getMax().equals("1"));
  }

  private ElementDefinitionSlicingComponent makeExtensionSlicing() {
        ElementDefinitionSlicingComponent slice = new ElementDefinitionSlicingComponent();
    slice.addDiscriminator().setPath("url").setType(DiscriminatorType.VALUE);
    slice.setOrdered(false);
    slice.setRules(SlicingRules.OPEN);
    return slice;
  }

  private boolean isExtension(ElementDefinition currentBase) {
    return currentBase.getPath().endsWith(".extension") || currentBase.getPath().endsWith(".modifierExtension");
  }

  private boolean hasInnerDiffMatches(StructureDefinitionDifferentialComponent context, String path, int start, int end, List<ElementDefinition> base, boolean allowSlices) throws DefinitionException {
    end = Math.min(context.getElement().size(), end);
    start = Math.max(0,  start);
    
    for (int i = start; i <= end; i++) {
      ElementDefinition ed = context.getElement().get(i);
      String statedPath = ed.getPath();
      if (!allowSlices && statedPath.equals(path) && ed.hasSliceName()) {
        return false;
      } else if (statedPath.startsWith(path+".")) {
        return true;
      } else if (path.endsWith("[x]") && statedPath.startsWith(path.substring(0, path.length() -3))) {
        return true;
      } else if (i != start && !allowSlices && !statedPath.startsWith(path+".")) {
        break;
      } else if (i != start && allowSlices && !statedPath.startsWith(path)) {
        break;
      }
    }
    return false;
  }

  private List<ElementDefinition> getDiffMatches(StructureDefinitionDifferentialComponent context, String path, int start, int end, String profileName) throws DefinitionException {
    List<ElementDefinition> result = new ArrayList<ElementDefinition>();
    String[] p = path.split("\\.");
    for (int i = start; i <= end; i++) {
      String statedPath = context.getElement().get(i).getPath();
      String[] sp = statedPath.split("\\.");
      boolean ok = sp.length == p.length;
      for (int j = 0; j < p.length; j++) {
        ok = ok && sp.length > j && (p[j].equals(sp[j]) || isSameBase(p[j], sp[j]));
      }
// don't need this debug check - everything is ok
//      if (ok != (statedPath.equals(path) || (path.endsWith("[x]") && statedPath.length() > path.length() - 2 &&
//            statedPath.substring(0, path.length()-3).equals(path.substring(0, path.length()-3)) &&
//            (statedPath.length() < path.length() || !statedPath.substring(path.length()).contains("."))))) {
//        System.out.println("mismatch in paths: "+statedPath +" vs " +path);
//      }
      if (ok) {
        /*
         * Commenting this out because it raises warnings when profiling inherited elements.  For example,
         * Error: unknown element 'Bundle.meta.profile' (or it is out of order) in profile ... (looking for 'Bundle.entry')
         * Not sure we have enough information here to do the check properly.  Might be better done when we're sorting the profile?

        if (i != start && result.isEmpty() && !path.startsWith(context.getElement().get(start).getPath()))
          messages.add(new ValidationMessage(Source.ProfileValidator, IssueType.VALUE, "StructureDefinition.differential.element["+Integer.toString(start)+"]", "Error: unknown element '"+context.getElement().get(start).getPath()+"' (or it is out of order) in profile '"+url+"' (looking for '"+path+"')", IssueSeverity.WARNING));

         */
        result.add(context.getElement().get(i));
      }
    }
    return result;
  }


  public boolean isSameBase(String p, String sp) {
    return (p.endsWith("[x]") && sp.startsWith(p.substring(0, p.length()-3))) || (sp.endsWith("[x]") && p.startsWith(sp.substring(0, sp.length()-3))) ;
  }

  private int findEndOfElement(StructureDefinitionDifferentialComponent context, int cursor) {
            int result = cursor;
            if (cursor >= context.getElement().size())
              return result;
            String path = context.getElement().get(cursor).getPath()+".";
            while (result < context.getElement().size()- 1 && context.getElement().get(result+1).getPath().startsWith(path))
              result++;
            return result;
          }

  private int findEndOfElement(StructureDefinitionSnapshotComponent context, int cursor) {
            int result = cursor;
            String path = context.getElement().get(cursor).getPath()+".";
            while (result < context.getElement().size()- 1 && context.getElement().get(result+1).getPath().startsWith(path))
              result++;
            return result;
          }

  private boolean unbounded(ElementDefinition definition) {
    StringType max = definition.getMaxElement();
    if (max == null)
      return false; // this is not valid
    if (max.getValue().equals("1"))
      return false;
    if (max.getValue().equals("0"))
      return false;
    return true;
  }

  private void updateFromDefinition(ElementDefinition dest, ElementDefinition source, String pn, boolean trimDifferential, String purl, StructureDefinition srcSD) throws DefinitionException, FHIRException {
    source.setUserData(GENERATED_IN_SNAPSHOT, dest);
    // we start with a clone of the base profile ('dest') and we copy from the profile ('source')
    // over the top for anything the source has
    ElementDefinition base = dest;
    ElementDefinition derived = source;
    derived.setUserData(DERIVATION_POINTER, base);
    boolean isExtension = checkExtensionDoco(base);


    // Before applying changes, apply them to what's in the profile
    StructureDefinition profile = null;
    if (base.hasSliceName())
      profile = base.getType().size() == 1 && base.getTypeFirstRep().hasProfile() ? context.fetchResource(StructureDefinition.class, base.getTypeFirstRep().getProfile().get(0).getValue()) : null;
    if (profile==null)
      profile = source.getType().size() == 1 && source.getTypeFirstRep().hasProfile() ? context.fetchResource(StructureDefinition.class, source.getTypeFirstRep().getProfile().get(0).getValue()) : null;
    if (profile != null) {
      ElementDefinition e = profile.getSnapshot().getElement().get(0);
      String webroot = profile.getUserString("webroot");

      base.setDefinition(processRelativeUrls(e.getDefinition(), webroot, baseSpecUrl(), context.getResourceNames(), masterSourceFileNames, true));
      base.setShort(e.getShort());
      if (e.hasCommentElement())
        base.setCommentElement(e.getCommentElement());
      if (e.hasRequirementsElement())
        base.setRequirementsElement(e.getRequirementsElement());
      base.getAlias().clear();
      base.getAlias().addAll(e.getAlias());
      base.getMapping().clear();
      base.getMapping().addAll(e.getMapping());
    } 
    if (derived != null) {
      if (derived.hasSliceName()) {
        base.setSliceName(derived.getSliceName());
      }
      
      if (derived.hasShortElement()) {
        if (!Base.compareDeep(derived.getShortElement(), base.getShortElement(), false))
          base.setShortElement(derived.getShortElement().copy());
        else if (trimDifferential)
          derived.setShortElement(null);
        else if (derived.hasShortElement())
          derived.getShortElement().setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasDefinitionElement()) {
        if (derived.getDefinition().startsWith("..."))
          base.setDefinition(base.getDefinition()+"\r\n"+derived.getDefinition().substring(3));
        else if (!Base.compareDeep(derived.getDefinitionElement(), base.getDefinitionElement(), false))
          base.setDefinitionElement(derived.getDefinitionElement().copy());
        else if (trimDifferential)
          derived.setDefinitionElement(null);
        else if (derived.hasDefinitionElement())
          derived.getDefinitionElement().setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasCommentElement()) {
        if (derived.getComment().startsWith("..."))
          base.setComment(base.getComment()+"\r\n"+derived.getComment().substring(3));
        else if (derived.hasCommentElement()!= base.hasCommentElement() || !Base.compareDeep(derived.getCommentElement(), base.getCommentElement(), false))
          base.setCommentElement(derived.getCommentElement().copy());
        else if (trimDifferential)
          base.setCommentElement(derived.getCommentElement().copy());
        else if (derived.hasCommentElement())
          derived.getCommentElement().setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasLabelElement()) {
        if (derived.getLabel().startsWith("..."))
          base.setLabel(base.getLabel()+"\r\n"+derived.getLabel().substring(3));
        else if (!base.hasLabelElement() || !Base.compareDeep(derived.getLabelElement(), base.getLabelElement(), false))
          base.setLabelElement(derived.getLabelElement().copy());
        else if (trimDifferential)
          base.setLabelElement(derived.getLabelElement().copy());
        else if (derived.hasLabelElement())
          derived.getLabelElement().setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasRequirementsElement()) {
        if (derived.getRequirements().startsWith("..."))
          base.setRequirements(base.getRequirements()+"\r\n"+derived.getRequirements().substring(3));
        else if (!base.hasRequirementsElement() || !Base.compareDeep(derived.getRequirementsElement(), base.getRequirementsElement(), false))
          base.setRequirementsElement(derived.getRequirementsElement().copy());
        else if (trimDifferential)
          base.setRequirementsElement(derived.getRequirementsElement().copy());
        else if (derived.hasRequirementsElement())
          derived.getRequirementsElement().setUserData(DERIVATION_EQUALS, true);
      }
      // sdf-9
      if (derived.hasRequirements() && !base.getPath().contains("."))
        derived.setRequirements(null);
      if (base.hasRequirements() && !base.getPath().contains("."))
        base.setRequirements(null);

      if (derived.hasAlias()) {
        if (!Base.compareDeep(derived.getAlias(), base.getAlias(), false))
          for (StringType s : derived.getAlias()) {
            if (!base.hasAlias(s.getValue()))
              base.getAlias().add(s.copy());
          }
        else if (trimDifferential)
          derived.getAlias().clear();
        else
          for (StringType t : derived.getAlias())
            t.setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasMinElement()) {
        if (!Base.compareDeep(derived.getMinElement(), base.getMinElement(), false)) {
          if (derived.getMin() < base.getMin() && !derived.hasSliceName()) // in a slice, minimum cardinality rules do not apply
            messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, pn+"."+source.getPath(), "Element "+base.getPath()+": derived min ("+Integer.toString(derived.getMin())+") cannot be less than base min ("+Integer.toString(base.getMin())+")", ValidationMessage.IssueSeverity.ERROR));
          base.setMinElement(derived.getMinElement().copy());
        } else if (trimDifferential)
          derived.setMinElement(null);
        else
          derived.getMinElement().setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasMaxElement()) {
        if (!Base.compareDeep(derived.getMaxElement(), base.getMaxElement(), false)) {
          if (isLargerMax(derived.getMax(), base.getMax()))
            messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, pn+"."+source.getPath(), "Element "+base.getPath()+": derived max ("+derived.getMax()+") cannot be greater than base max ("+base.getMax()+")", ValidationMessage.IssueSeverity.ERROR));
          base.setMaxElement(derived.getMaxElement().copy());
        } else if (trimDifferential)
          derived.setMaxElement(null);
        else
          derived.getMaxElement().setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasFixed()) {
        if (!Base.compareDeep(derived.getFixed(), base.getFixed(), true)) {
          base.setFixed(derived.getFixed().copy());
        } else if (trimDifferential)
          derived.setFixed(null);
        else
          derived.getFixed().setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasPattern()) {
        if (!Base.compareDeep(derived.getPattern(), base.getPattern(), false)) {
          base.setPattern(derived.getPattern().copy());
        } else
          if (trimDifferential)
            derived.setPattern(null);
          else
            derived.getPattern().setUserData(DERIVATION_EQUALS, true);
      }

      for (ElementDefinitionExampleComponent ex : derived.getExample()) {
        boolean found = false;
        for (ElementDefinitionExampleComponent exS : base.getExample())
          if (Base.compareDeep(ex, exS, false))
            found = true;
        if (!found)
          base.addExample(ex.copy());
        else if (trimDifferential)
          derived.getExample().remove(ex);
        else
          ex.setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasMaxLengthElement()) {
        if (!Base.compareDeep(derived.getMaxLengthElement(), base.getMaxLengthElement(), false))
          base.setMaxLengthElement(derived.getMaxLengthElement().copy());
        else if (trimDifferential)
          derived.setMaxLengthElement(null);
        else
          derived.getMaxLengthElement().setUserData(DERIVATION_EQUALS, true);
      }
  
      if (derived.hasMaxValue()) {
        if (!Base.compareDeep(derived.getMaxValue(), base.getMaxValue(), false))
          base.setMaxValue(derived.getMaxValue().copy());
        else if (trimDifferential)
          derived.setMaxValue(null);
        else
          derived.getMaxValue().setUserData(DERIVATION_EQUALS, true);
      }
  
      if (derived.hasMinValue()) {
        if (!Base.compareDeep(derived.getMinValue(), base.getMinValue(), false))
          base.setMinValue(derived.getMinValue().copy());
        else if (trimDifferential)
          derived.setMinValue(null);
        else
          derived.getMinValue().setUserData(DERIVATION_EQUALS, true);
      }

      // todo: what to do about conditions?
      // condition : id 0..*

      if (derived.hasMustSupportElement()) {
        if (!(base.hasMustSupportElement() && Base.compareDeep(derived.getMustSupportElement(), base.getMustSupportElement(), false))) {
          if (base.hasMustSupport() && base.getMustSupport() && !derived.getMustSupport()) {
            messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, pn+"."+derived.getPath(), "Illegal constraint [must-support = false] when [must-support = true] in the base profile", ValidationMessage.IssueSeverity.ERROR));
          }
          base.setMustSupportElement(derived.getMustSupportElement().copy());
        } else if (trimDifferential)
          derived.setMustSupportElement(null);
        else
          derived.getMustSupportElement().setUserData(DERIVATION_EQUALS, true);
      }


      // profiles cannot change : isModifier, defaultValue, meaningWhenMissing
      // but extensions can change isModifier
      if (isExtension) {
        if (derived.hasIsModifierElement() && !(base.hasIsModifierElement() && Base.compareDeep(derived.getIsModifierElement(), base.getIsModifierElement(), false)))
          base.setIsModifierElement(derived.getIsModifierElement().copy());
        else if (trimDifferential)
          derived.setIsModifierElement(null);
        else if (derived.hasIsModifierElement())
          derived.getIsModifierElement().setUserData(DERIVATION_EQUALS, true);
        if (derived.hasIsModifierReasonElement() && !(base.hasIsModifierReasonElement() && Base.compareDeep(derived.getIsModifierReasonElement(), base.getIsModifierReasonElement(), false)))
          base.setIsModifierReasonElement(derived.getIsModifierReasonElement().copy());
        else if (trimDifferential)
          derived.setIsModifierReasonElement(null);
        else if (derived.hasIsModifierReasonElement())
          derived.getIsModifierReasonElement().setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasBinding()) {
        if (!base.hasBinding() || !Base.compareDeep(derived.getBinding(), base.getBinding(), false)) {
          if (base.hasBinding() && base.getBinding().getStrength() == BindingStrength.REQUIRED && derived.getBinding().getStrength() != BindingStrength.REQUIRED)
            messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, pn+"."+derived.getPath(), "illegal attempt to change the binding on "+derived.getPath()+" from "+base.getBinding().getStrength().toCode()+" to "+derived.getBinding().getStrength().toCode(), ValidationMessage.IssueSeverity.ERROR));
//            throw new DefinitionException("StructureDefinition "+pn+" at "+derived.getPath()+": illegal attempt to change a binding from "+base.getBinding().getStrength().toCode()+" to "+derived.getBinding().getStrength().toCode());
          else if (base.hasBinding() && derived.hasBinding() && base.getBinding().getStrength() == BindingStrength.REQUIRED && base.getBinding().hasValueSet() && derived.getBinding().hasValueSet()) {
            ValueSet baseVs = context.fetchResource(ValueSet.class, base.getBinding().getValueSet());
            ValueSet contextVs = context.fetchResource(ValueSet.class, derived.getBinding().getValueSet());
            if (baseVs == null) {
              messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, pn+"."+base.getPath(), "Binding "+base.getBinding().getValueSet()+" could not be located", ValidationMessage.IssueSeverity.WARNING));
            } else if (contextVs == null) {
              messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, pn+"."+derived.getPath(), "Binding "+derived.getBinding().getValueSet()+" could not be located", ValidationMessage.IssueSeverity.WARNING));
            } else {
              ValueSetExpansionOutcome expBase = context.expandVS(baseVs, true, false);
              ValueSetExpansionOutcome expDerived = context.expandVS(contextVs, true, false);
              if (expBase.getValueset() == null)
                messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, pn+"."+base.getPath(), "Binding "+base.getBinding().getValueSet()+" could not be expanded", ValidationMessage.IssueSeverity.WARNING));
              else if (expDerived.getValueset() == null)
                messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, pn+"."+derived.getPath(), "Binding "+derived.getBinding().getValueSet()+" could not be expanded", ValidationMessage.IssueSeverity.WARNING));
              else if (ToolingExtensions.hasExtension(expBase.getValueset().getExpansion(), ToolingExtensions.EXT_EXP_TOOCOSTLY))
                messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, pn+"."+derived.getPath(), "Unable to check if "+derived.getBinding().getValueSet()+" is a proper subset of " +base.getBinding().getValueSet()+" - base value set is too large to check", ValidationMessage.IssueSeverity.WARNING));
              else if (!isSubset(expBase.getValueset(), expDerived.getValueset()))
                messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, pn+"."+derived.getPath(), "Binding "+derived.getBinding().getValueSet()+" is not a subset of binding "+base.getBinding().getValueSet(), ValidationMessage.IssueSeverity.ERROR));
            }
          }
          ElementDefinitionBindingComponent d = derived.getBinding();
          ElementDefinitionBindingComponent nb = base.getBinding().copy();
          if (!COPY_BINDING_EXTENSIONS) {
            nb.getExtension().clear();
          }
          nb.setDescription(null);
          nb.getExtension().addAll(d.getExtension());
          if (d.hasStrength()) {
            nb.setStrength(d.getStrength());
          }
          if (d.hasDescription()) {
            nb.setDescription(d.getDescription());
          }
          if (d.hasValueSet()) {
            nb.setValueSet(d.getValueSet());
          }
          base.setBinding(nb);
        } else if (trimDifferential)
          derived.setBinding(null);
        else
          derived.getBinding().setUserData(DERIVATION_EQUALS, true);
      } // else if (base.hasBinding() && doesn't have bindable type )
        //  base

      if (derived.hasIsSummaryElement()) {
        if (!Base.compareDeep(derived.getIsSummaryElement(), base.getIsSummaryElement(), false)) {
          if (base.hasIsSummary() && !context.getVersion().equals("1.4.0")) // work around a known issue with some 1.4.0 cosntraints
            throw new Error(context.formatMessage(I18nConstants.ERROR_IN_PROFILE__AT__BASE_ISSUMMARY___DERIVED_ISSUMMARY__, purl, derived.getPath(), base.getIsSummaryElement().asStringValue(), derived.getIsSummaryElement().asStringValue()));
          base.setIsSummaryElement(derived.getIsSummaryElement().copy());
        } else if (trimDifferential)
          derived.setIsSummaryElement(null);
        else
          derived.getIsSummaryElement().setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasType()) {
        if (!Base.compareDeep(derived.getType(), base.getType(), false)) {
          if (base.hasType()) {
            for (TypeRefComponent ts : derived.getType()) {
              checkTypeDerivation(purl, srcSD, base, derived, ts);
            }
          }
          base.getType().clear();
          for (TypeRefComponent t : derived.getType()) {
            TypeRefComponent tt = t.copy();
//            tt.setUserData(DERIVATION_EQUALS, true);
            base.getType().add(tt);
          }
        }
        else if (trimDifferential)
          derived.getType().clear();
        else
          for (TypeRefComponent t : derived.getType())
            t.setUserData(DERIVATION_EQUALS, true);
      }

      if (derived.hasMapping()) {
        // todo: mappings are not cumulative - one replaces another
        if (!Base.compareDeep(derived.getMapping(), base.getMapping(), false)) {
          for (ElementDefinitionMappingComponent s : derived.getMapping()) {
            boolean found = false;
            for (ElementDefinitionMappingComponent d : base.getMapping()) {
              found = found || (d.getIdentity().equals(s.getIdentity()) && d.getMap().equals(s.getMap()));
            }
            if (!found) {
              base.getMapping().add(s);
            }
          }
        }
        else if (trimDifferential) {
          derived.getMapping().clear();
        } else { 
          for (ElementDefinitionMappingComponent t : derived.getMapping()) {
            t.setUserData(DERIVATION_EQUALS, true);
          }
        }
      }
      for (ElementDefinitionMappingComponent m : base.getMapping()) {
        if (m.hasMap()) {
          m.setMap(m.getMap().trim());
        }
      }

      // todo: constraints are cumulative. there is no replacing
      for (ElementDefinitionConstraintComponent s : base.getConstraint()) { 
        s.setUserData(IS_DERIVED, true);
        if (!s.hasSource()) {
          s.setSource(srcSD.getUrl());
        } 
      }
      if (derived.hasConstraint()) {
        for (ElementDefinitionConstraintComponent s : derived.getConstraint()) {
          if (!base.hasConstraint(s.getKey())) {
            ElementDefinitionConstraintComponent inv = s.copy();
            base.getConstraint().add(inv);
          }
        }
      }
      for (IdType id : derived.getCondition()) {
        if (!base.hasCondition(id)) {
          base.getCondition().add(id);
        }
      }
      
      // now, check that we still have a bindable type; if not, delete the binding - see task 8477
      if (dest.hasBinding() && !hasBindableType(dest)) {
        dest.setBinding(null);
      }
        
      // finally, we copy any extensions from source to dest
      for (Extension ex : derived.getExtension()) {
        StructureDefinition sd  = context.fetchResource(StructureDefinition.class, ex.getUrl());
        if (sd == null || sd.getSnapshot() == null || sd.getSnapshot().getElementFirstRep().getMax().equals("1")) {
          ToolingExtensions.removeExtension(dest, ex.getUrl());
        }
        dest.addExtension(ex.copy());
      }
    }
    if (dest.hasFixed()) {
      checkTypeOk(dest, dest.getFixed().fhirType(), srcSD);
    }
    if (dest.hasPattern()) {
      checkTypeOk(dest, dest.getPattern().fhirType(), srcSD);
    }
  }

  public void checkTypeDerivation(String purl, StructureDefinition srcSD, ElementDefinition base, ElementDefinition derived, TypeRefComponent ts) {
    boolean ok = false;
    CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder();
    String t = ts.getWorkingCode();
    for (TypeRefComponent td : base.getType()) {;
      String tt = td.getWorkingCode();
      b.append(tt);
      if (td.hasCode() && (tt.equals(t))) {
        ok = true;
      }
      if (!ok) {
        StructureDefinition sdt = context.fetchTypeDefinition(tt);
        if (sdt != null && (sdt.getAbstract() || sdt.getKind() == StructureDefinitionKind.LOGICAL)) {
          StructureDefinition sdb = context.fetchTypeDefinition(t);
          while (sdb != null && !ok) {
            ok = sdb.getType().equals(sdt.getType());
            sdb = context.fetchResource(StructureDefinition.class, sdb.getBaseDefinition());
          }
        }
      }
     // work around for old badly generated SDs
      if (DONT_DO_THIS && Utilities.existsInList(tt, "Extension", "uri", "string", "Element")) {
        ok = true;
      }
      if (DONT_DO_THIS && Utilities.existsInList(tt, "Resource","DomainResource") && pkp.isResource(t)) {
        ok = true;
      }
      if (ok && ts.hasTargetProfile()) {
        // check that any derived target has a reference chain back to one of the base target profiles
        for (UriType u : ts.getTargetProfile()) {
          String url = u.getValue();
          boolean tgtOk = !td.hasTargetProfile() || td.hasTargetProfile(url);
          while (url != null && !tgtOk) {
            StructureDefinition sd = context.fetchRawProfile(url);
            if (sd == null) {
              if (messages != null) {
                messages.add(new ValidationMessage(Source.InstanceValidator, IssueType.BUSINESSRULE, purl+"#"+derived.getPath(), "Cannot check whether the target profile "+url+" is valid constraint on the base because it is not known", IssueSeverity.WARNING));
              }
              url = null;
              tgtOk = true; // suppress error message
            } else {
              url = sd.getBaseDefinition();
              tgtOk = td.hasTargetProfile(url);
            }
          }
          if (!tgtOk) {
            if (messages == null) {
              throw new FHIRException(context.formatMessage(I18nConstants.ERROR_AT__THE_TARGET_PROFILE__IS_NOT__VALID_CONSTRAINT_ON_THE_BASE_, purl, derived.getPath(), url, td.getTargetProfile()));
            } else {
              messages.add(new ValidationMessage(Source.InstanceValidator, IssueType.BUSINESSRULE, derived.getPath(), "The target profile "+u.getValue()+" is not a valid constraint on the base ("+td.getTargetProfile()+") at "+derived.getPath(), IssueSeverity.ERROR));
            }
          }
        }
      }
    }
    if (!ok) {
      throw new DefinitionException(context.formatMessage(I18nConstants.STRUCTUREDEFINITION__AT__ILLEGAL_CONSTRAINED_TYPE__FROM__IN_, purl, derived.getPath(), t, b.toString(), srcSD.getUrl()));
    }
  }


  public void checkTypeOk(ElementDefinition dest, String ft, StructureDefinition sd) {
    boolean ok = false;
    Set<String> types = new HashSet<>();
    if (dest.getPath().contains(".")) {
      for (TypeRefComponent t : dest.getType()) {
        if (t.hasCode()) {
          types.add(t.getWorkingCode());
        }
        ok = ft.equals(t.getWorkingCode());
      }
    } else {
      types.add(sd.getType());
      ok = ft.equals(sd.getType());

    }
    if (!ok) {
      messages.add(new ValidationMessage(Source.InstanceValidator, IssueType.CONFLICT, dest.getId(), "The fixed value has type '"+ft+"' which is not valid (valid "+Utilities.pluralize("type", dest.getType().size())+": "+types.toString()+")", IssueSeverity.ERROR));
    }
  }

  private boolean hasBindableType(ElementDefinition ed) {
    for (TypeRefComponent tr : ed.getType()) {
      if (Utilities.existsInList(tr.getWorkingCode(), "Coding", "CodeableConcept", "Quantity", "uri", "string", "code")) {
        return true;
      }
      StructureDefinition sd = context.fetchTypeDefinition(tr.getCode());
      if (sd != null && sd.hasExtension(ToolingExtensions.EXT_BINDING_STYLE)) {
        return true;
      }
    }
    return false;
  }


  private boolean isLargerMax(String derived, String base) {
    if ("*".equals(base)) {
      return false;
    }
    if ("*".equals(derived)) {
      return true;
    }
    return Integer.parseInt(derived) > Integer.parseInt(base);
  }


  private boolean isSubset(ValueSet expBase, ValueSet expDerived) {
    return codesInExpansion(expDerived.getExpansion().getContains(), expBase.getExpansion());
  }


  private boolean codesInExpansion(List<ValueSetExpansionContainsComponent> contains, ValueSetExpansionComponent expansion) {
    for (ValueSetExpansionContainsComponent cc : contains) {
      if (!inExpansion(cc, expansion.getContains())) {
        return false;
      }
      if (!codesInExpansion(cc.getContains(), expansion)) {
        return false;
      }
    }
    return true;
  }


  private boolean inExpansion(ValueSetExpansionContainsComponent cc, List<ValueSetExpansionContainsComponent> contains) {
    for (ValueSetExpansionContainsComponent cc1 : contains) {
      if (cc.getSystem().equals(cc1.getSystem()) && cc.getCode().equals(cc1.getCode())) {
        return true;
      }
      if (inExpansion(cc,  cc1.getContains())) {
        return true;
      }
    }
    return false;
  }

  public void closeDifferential(StructureDefinition base, StructureDefinition derived) throws FHIRException {
    for (ElementDefinition edb : base.getSnapshot().getElement()) {
      if (isImmediateChild(edb) && !edb.getPath().endsWith(".id")) {
        ElementDefinition edm = getMatchInDerived(edb, derived.getDifferential().getElement());
        if (edm == null) {
          ElementDefinition edd = derived.getDifferential().addElement();
          edd.setPath(edb.getPath());
          edd.setMax("0");
        } else if (edb.hasSlicing()) {
          closeChildren(base, edb, derived, edm);
        }
      }
    }
    sortDifferential(base, derived, derived.getName(), new ArrayList<String>(), false);
  }

  private void closeChildren(StructureDefinition base, ElementDefinition edb, StructureDefinition derived, ElementDefinition edm) {
    String path = edb.getPath()+".";
    int baseStart = base.getSnapshot().getElement().indexOf(edb);
    int baseEnd = findEnd(base.getSnapshot().getElement(), edb, baseStart+1);
    int diffStart = derived.getDifferential().getElement().indexOf(edm);
    int diffEnd = findEnd(derived.getDifferential().getElement(), edm, diffStart+1);
    
    for (int cBase = baseStart; cBase < baseEnd; cBase++) {
      ElementDefinition edBase = base.getSnapshot().getElement().get(cBase);
      if (isImmediateChild(edBase, edb)) {
        ElementDefinition edMatch = getMatchInDerived(edBase, derived.getDifferential().getElement(), diffStart, diffEnd);
        if (edMatch == null) {
          ElementDefinition edd = derived.getDifferential().addElement();
          edd.setPath(edBase.getPath());
          edd.setMax("0");
        } else {
          closeChildren(base, edBase, derived, edMatch);
        }        
      }
    }
  }




  private int findEnd(List<ElementDefinition> list, ElementDefinition ed, int cursor) {
    String path = ed.getPath()+".";
    while (cursor < list.size() && list.get(cursor).getPath().startsWith(path)) {
      cursor++;
    }
    return cursor;
  }


  private ElementDefinition getMatchInDerived(ElementDefinition ed, List<ElementDefinition> list) {
    for (ElementDefinition t : list) {
      if (t.getPath().equals(ed.getPath())) {
        return t;
      }
    }
    return null;
  }

  private ElementDefinition getMatchInDerived(ElementDefinition ed, List<ElementDefinition> list, int start, int end) {
    for (int i = start; i < end; i++) {
      ElementDefinition t = list.get(i);
      if (t.getPath().equals(ed.getPath())) {
        return t;
      }
    }
    return null;
  }


  private boolean isImmediateChild(ElementDefinition ed) {
    String p = ed.getPath();
    if (!p.contains(".")) {
      return false;
    }
    p = p.substring(p.indexOf(".")+1);
    return !p.contains(".");
  }

  private boolean isImmediateChild(ElementDefinition candidate, ElementDefinition base) {
    String p = candidate.getPath();
    if (!p.contains("."))
      return false;
    if (!p.startsWith(base.getPath()+"."))
      return false;
    p = p.substring(base.getPath().length()+1);
    return !p.contains(".");
  }

  public XhtmlNode generateExtensionTable(String defFile, StructureDefinition ed, String imageFolder, boolean inlineGraphics, boolean full, String corePath, String imagePath, Set<String> outputTracker) throws IOException, FHIRException {
    HierarchicalTableGenerator gen = new HierarchicalTableGenerator(imageFolder, inlineGraphics, true);
    gen.setTranslator(getTranslator());
    TableModel model = gen.initNormalTable(corePath, false, true, ed.getId()+(full ? "f" : "n"), true);

    boolean deep = false;
    String m = "";
    boolean vdeep = false;
    if (ed.getSnapshot().getElementFirstRep().getIsModifier())
      m = "modifier_";
    for (ElementDefinition eld : ed.getSnapshot().getElement()) {
      deep = deep || eld.getPath().contains("Extension.extension.");
      vdeep = vdeep || eld.getPath().contains("Extension.extension.extension.");
    }
    Row r = gen.new Row();
    model.getRows().add(r);
    String en;
    if (!full)
      en = ed.getName();
    else if (ed.getSnapshot().getElement().get(0).getIsModifier())
      en = "modifierExtension";
    else 
      en = "extension";
    
    r.getCells().add(gen.new Cell(null, defFile == null ? "" : defFile+"-definitions.html#extension."+ed.getName(), en, null, null));
    r.getCells().add(gen.new Cell());
    r.getCells().add(gen.new Cell(null, null, describeCardinality(ed.getSnapshot().getElement().get(0), null, new UnusedTracker()), null, null));

    ElementDefinition ved = null;
    if (full || vdeep) {
      r.getCells().add(gen.new Cell("", "", "Extension", null, null));

      r.setIcon(deep ? "icon_"+m+"extension_complex.png" : "icon_extension_simple.png", deep ? HierarchicalTableGenerator.TEXT_ICON_EXTENSION_COMPLEX : HierarchicalTableGenerator.TEXT_ICON_EXTENSION_SIMPLE);
      List<ElementDefinition> children = getChildren(ed.getSnapshot().getElement(), ed.getSnapshot().getElement().get(0));
      for (ElementDefinition child : children)
        if (!child.getPath().endsWith(".id")) {
          List<StructureDefinition> sdl = new ArrayList<>();
          sdl.add(ed);
          genElement(defFile == null ? "" : defFile+"-definitions.html#extension.", gen, r.getSubRows(), child, ed.getSnapshot().getElement(), sdl, true, defFile, true, full, corePath, imagePath, true, false, false, false, null, false);
        }
    } else if (deep) {
      List<ElementDefinition> children = new ArrayList<ElementDefinition>();
      for (ElementDefinition ted : ed.getSnapshot().getElement()) {
        if (ted.getPath().equals("Extension.extension"))
          children.add(ted);
      }

      r.getCells().add(gen.new Cell("", "", "Extension", null, null));
      r.setIcon("icon_"+m+"extension_complex.png", HierarchicalTableGenerator.TEXT_ICON_EXTENSION_COMPLEX);
      
      for (ElementDefinition c : children) {
        ved = getValueFor(ed, c);
        ElementDefinition ued = getUrlFor(ed, c);
        if (ved != null && ued != null) {
          Row r1 = gen.new Row();
          r.getSubRows().add(r1);
          r1.getCells().add(gen.new Cell(null, defFile == null ? "" : defFile+"-definitions.html#extension."+ed.getName(), ((UriType) ued.getFixed()).getValue(), null, null));
          r1.getCells().add(gen.new Cell());
          r1.getCells().add(gen.new Cell(null, null, describeCardinality(c, null, new UnusedTracker()), null, null));
          genTypes(gen, r1, ved, defFile, ed, corePath, imagePath, false, false);
          Cell cell = gen.new Cell();
          cell.addMarkdown(c.getDefinition());
          r1.getCells().add(cell);
          r1.setIcon("icon_"+m+"extension_simple.png", HierarchicalTableGenerator.TEXT_ICON_EXTENSION_SIMPLE);      
        }
      }
    } else  {
      for (ElementDefinition ted : ed.getSnapshot().getElement()) {
        if (ted.getPath().startsWith("Extension.value"))
          ved = ted;
      }

      genTypes(gen, r, ved, defFile, ed, corePath, imagePath, false, false);

      r.setIcon("icon_"+m+"extension_simple.png", HierarchicalTableGenerator.TEXT_ICON_EXTENSION_SIMPLE);      
    }
    Cell c = gen.new Cell("", "", "URL = "+ed.getUrl(), null, null);
    Piece cc = gen.new Piece(null, ed.getName()+": ", null);
    c.addPiece(gen.new Piece("br")).addPiece(cc);
    c.addMarkdown(ed.getDescription());
    
    if (!full && !(deep || vdeep) && ved != null && ved.hasBinding()) {  
        c.addPiece(gen.new Piece("br"));
      BindingResolution br = pkp.resolveBinding(ed, ved.getBinding(), ved.getPath());
      c.getPieces().add(checkForNoChange(ved.getBinding(), gen.new Piece(null, translate("sd.table", "Binding")+": ", null).addStyle("font-weight:bold")));
      c.getPieces().add(checkForNoChange(ved.getBinding(), gen.new Piece(br.url == null ? null : Utilities.isAbsoluteUrl(br.url) || !pkp.prependLinks() ? br.url : corePath+br.url, br.display, null)));
      if (ved.getBinding().hasStrength()) {
        c.getPieces().add(checkForNoChange(ved.getBinding(), gen.new Piece(null, " (", null)));
        c.getPieces().add(checkForNoChange(ved.getBinding(), gen.new Piece(corePath+"terminologies.html#"+ved.getBinding().getStrength().toCode(), egt(ved.getBinding().getStrengthElement()), ved.getBinding().getStrength().getDefinition())));              
        c.getPieces().add(gen.new Piece(null, ")", null));
      }
      if (ved.getBinding().hasDescription() && MarkDownProcessor.isSimpleMarkdown(ved.getBinding().getDescription())) {
        c.getPieces().add(gen.new Piece(null, ": ", null));
        c.addMarkdownNoPara(PublicationHacker.fixBindingDescriptions(context, ved.getBinding().getDescriptionElement()).asStringValue());
      }
    }
    c.addPiece(gen.new Piece("br")).addPiece(gen.new Piece(null, describeExtensionContext(ed), null));
    r.getCells().add(c);
    
    try {
      return gen.generate(model, corePath, 0, outputTracker);
        } catch (org.hl7.fhir.exceptions.FHIRException e) {
                throw new FHIRException(e.getMessage(), e);
        }
  }

  private ElementDefinition getUrlFor(StructureDefinition ed, ElementDefinition c) {
    int i = ed.getSnapshot().getElement().indexOf(c) + 1;
    while (i < ed.getSnapshot().getElement().size() && ed.getSnapshot().getElement().get(i).getPath().startsWith(c.getPath()+".")) {
      if (ed.getSnapshot().getElement().get(i).getPath().equals(c.getPath()+".url"))
        return ed.getSnapshot().getElement().get(i);
      i++;
    }
    return null;
  }

  private ElementDefinition getValueFor(StructureDefinition ed, ElementDefinition c) {
    int i = ed.getSnapshot().getElement().indexOf(c) + 1;
    while (i < ed.getSnapshot().getElement().size() && ed.getSnapshot().getElement().get(i).getPath().startsWith(c.getPath()+".")) {
      if (ed.getSnapshot().getElement().get(i).getPath().startsWith(c.getPath()+".value"))
        return ed.getSnapshot().getElement().get(i);
      i++;
    }
    return null;
  }

  private static final int AGG_NONE = 0;
  private static final int AGG_IND = 1;
  private static final int AGG_GR = 2;
  private static final boolean TABLE_FORMAT_FOR_FIXED_VALUES = false;
  
  private Cell genTypes(HierarchicalTableGenerator gen, Row r, ElementDefinition e, String profileBaseFileName, StructureDefinition profile, String corePath, String imagePath, boolean root, boolean mustSupportMode) {
    Cell c = gen.new Cell();
    r.getCells().add(c);
    if (e.hasContentReference()) {
      ElementInStructure ed = getElementByName(profile.getSnapshot().getElement(), e.getContentReference(), profile);
      if (ed == null)
        c.getPieces().add(gen.new Piece(null, translate("sd.table", "Unknown reference to %s", e.getContentReference()), null));
      else {
        if (ed.getSource() == profile) {
          c.getPieces().add(gen.new Piece(null, translate("sd.table", "See ", ed.getElement().getPath()), null));
          c.getPieces().add(gen.new Piece("#"+ed.getElement().getPath(), tail(ed.getElement().getPath()), ed.getElement().getPath()));
        } else {
          c.getPieces().add(gen.new Piece(null, translate("sd.table", "See ", ed.getElement().getPath()), null));
          c.getPieces().add(gen.new Piece(pfx(corePath, ed.getSource().getUserString("path"))+"#"+ed.getElement().getPath(), tail(ed.getElement().getPath())+" ("+ed.getSource().getType()+")", ed.getElement().getPath()));
        }
      }
      return c;
    }
    List<TypeRefComponent> types = e.getType();
    if (!e.hasType()) {
      if (root) { // we'll use base instead of types then
        StructureDefinition bsd = profile == null ? null : context.fetchResource(StructureDefinition.class, profile.getBaseDefinition());
        if (bsd != null) {
          if (bsd.hasUserData("path")) {
            c.getPieces().add(gen.new Piece(Utilities.isAbsoluteUrl(bsd.getUserString("path")) ? bsd.getUserString("path") : imagePath +bsd.getUserString("path"), bsd.getName(), null));
          } else {
            c.getPieces().add(gen.new Piece(null, bsd.getName(), null));
          }
        }
        return c;
      } else if (e.hasContentReference()) {
        return c;
      } else {
        ElementDefinition d = (ElementDefinition) e.getUserData(DERIVATION_POINTER);
        if (d != null && d.hasType()) {
          types = new ArrayList<ElementDefinition.TypeRefComponent>();
          for (TypeRefComponent tr : d.getType()) {
            TypeRefComponent tt = tr.copy();
            tt.setUserData(DERIVATION_EQUALS, true);
            types.add(tt);
          }
        } else {
          return c;
        }
      }
    }

    boolean first = true;

    TypeRefComponent tl = null;
    for (TypeRefComponent t : types) {
      if (!mustSupportMode || allTypesMustSupport(e) || isMustSupport(t)) {
        if (first) {
          first = false;
        } else {
          c.addPiece(checkForNoChange(tl, gen.new Piece(null,", ", null)));
        }
        tl = t;
        if (t.hasTarget()) {
          c.getPieces().add(gen.new Piece(corePath+"references.html", t.getWorkingCode(), null));
          if (!mustSupportMode && isMustSupportDirect(t) && e.getMustSupport()) {
            c.addPiece(gen.new Piece(null, " ", null));
            c.addStyledText(translate("sd.table", "This type must be supported"), "S", "white", "red", null, false);
          }
          c.getPieces().add(gen.new Piece(null, "(", null));
          boolean tfirst = true;
          for (CanonicalType u : t.getTargetProfile()) {
            if (!mustSupportMode || allProfilesMustSupport(t.getTargetProfile()) || isMustSupport(u)) {
              if (tfirst)
                tfirst = false;
              else
                c.addPiece(gen.new Piece(null, " | ", null));
              genTargetLink(gen, profileBaseFileName, corePath, c, t, u.getValue());
              if (!mustSupportMode && isMustSupport(u) && e.getMustSupport()) {
                c.addPiece(gen.new Piece(null, " ", null));
                c.addStyledText(translate("sd.table", "This target must be supported"), "S", "white", "red", null, false);
              }
            }
          }
          c.getPieces().add(gen.new Piece(null, ")", null));
          if (t.getAggregation().size() > 0) {
            c.getPieces().add(gen.new Piece(corePath+"valueset-resource-aggregation-mode.html", " {", null));
            boolean firstA = true;
            for (Enumeration<AggregationMode> a : t.getAggregation()) {
              if (firstA = true)
                firstA = false;
              else
                c.getPieces().add(gen.new Piece(corePath+"valueset-resource-aggregation-mode.html", ", ", null));
              c.getPieces().add(gen.new Piece(corePath+"valueset-resource-aggregation-mode.html", codeForAggregation(a.getValue()), hintForAggregation(a.getValue())));
            }
            c.getPieces().add(gen.new Piece(corePath+"valueset-resource-aggregation-mode.html", "}", null));
          }
        } else if (t.hasProfile() && (!t.getWorkingCode().equals("Extension") || isProfiledType(t.getProfile()))) { // a profiled type
          String ref;
          boolean pfirst = true;
          for (CanonicalType p : t.getProfile()) {
            if (!mustSupportMode || allProfilesMustSupport(t.getProfile()) || isMustSupport(p)) {
              if (pfirst) {
                pfirst = false;
              } else {
                c.addPiece(checkForNoChange(tl, gen.new Piece(null,", ", null)));
              }          

              ref = pkp == null ? null : pkp.getLinkForProfile(profile, p.getValue());
              if (ref != null) {
                String[] parts = ref.split("\\|");
                if (parts[0].startsWith("http:") || parts[0].startsWith("https:")) {
                  //            c.addPiece(checkForNoChange(t, gen.new Piece(parts[0], "<" + parts[1] + ">", t.getCode()))); Lloyd
                  c.addPiece(checkForNoChange(t, gen.new Piece(parts[0], parts[1], t.getWorkingCode())));
                } else {
                  //            c.addPiece(checkForNoChange(t, gen.new Piece((t.getProfile().startsWith(corePath)? corePath: "")+parts[0], "<" + parts[1] + ">", t.getCode())));
                  c.addPiece(checkForNoChange(t, gen.new Piece((p.getValue().startsWith(corePath+"StructureDefinition")? corePath: "")+parts[0], parts[1], t.getWorkingCode())));
                }
              } else
                c.addPiece(checkForNoChange(t, gen.new Piece((p.getValue().startsWith(corePath)? corePath: "")+ref, t.getWorkingCode(), null)));
              if (!mustSupportMode && isMustSupport(p) && e.getMustSupport()) {
                c.addPiece(gen.new Piece(null, " ", null));
                c.addStyledText(translate("sd.table", "This profile must be supported"), "S", "white", "red", null, false);
              }
            }
          }
        } else {
          String tc = t.getWorkingCode();
          if (Utilities.isAbsoluteUrl(tc)) {
            StructureDefinition sd = context.fetchTypeDefinition(tc);
            if (sd == null) {
              c.addPiece(checkForNoChange(t, gen.new Piece(pkp.getLinkFor(corePath, tc), tc, null)));
            } else {
              c.addPiece(checkForNoChange(t, gen.new Piece(pkp.getLinkFor(corePath, tc), sd.getType(), null)));           
            }
          } else if (pkp != null && pkp.hasLinkFor(tc)) {
            c.addPiece(checkForNoChange(t, gen.new Piece(pkp.getLinkFor(corePath, tc), tc, null)));
          } else {
            c.addPiece(checkForNoChange(t, gen.new Piece(null, tc, null)));
          }
          if (!mustSupportMode && isMustSupportDirect(t) && e.getMustSupport()) {
            c.addPiece(gen.new Piece(null, " ", null));
            c.addStyledText(translate("sd.table", "This type must be supported"), "S", "white", "red", null, false);
          }
        }
      }
    }
    return c;
  }


  private String pfx(String prefix, String url) {
    return Utilities.isAbsoluteUrl(url) ? url : prefix + url;
  }

  public void genTargetLink(HierarchicalTableGenerator gen, String profileBaseFileName, String corePath, Cell c, TypeRefComponent t, String u) {
    if (u.startsWith("http://hl7.org/fhir/StructureDefinition/")) {
      StructureDefinition sd = context.fetchResource(StructureDefinition.class, u);
      if (sd != null) {
        String disp = sd.hasTitle() ? sd.getTitle() : sd.getName();
        c.addPiece(checkForNoChange(t, gen.new Piece(checkPrepend(corePath, sd.getUserString("path")), disp, null)));
      } else {
        String rn = u.substring(40);
        c.addPiece(checkForNoChange(t, gen.new Piece(pkp.getLinkFor(corePath, rn), rn, null)));
      }
    } else if (Utilities.isAbsoluteUrl(u)) {
      StructureDefinition sd = context.fetchResource(StructureDefinition.class, u);
      if (sd != null) {
        String disp = sd.hasTitle() ? sd.getTitle() : sd.getName();
        String ref = pkp.getLinkForProfile(null, sd.getUrl());
        if (ref != null && ref.contains("|"))
          ref = ref.substring(0,  ref.indexOf("|"));
        c.addPiece(checkForNoChange(t, gen.new Piece(ref, disp, null)));
      } else
        c.addPiece(checkForNoChange(t, gen.new Piece(null, u, null)));        
    } else if (t.hasTargetProfile() && u.startsWith("#"))
      c.addPiece(checkForNoChange(t, gen.new Piece(corePath+profileBaseFileName+"."+u.substring(1).toLowerCase()+".html", u, null)));
  }

  private boolean isProfiledType(List<CanonicalType> theProfile) {
    for (CanonicalType next : theProfile){
      if (StringUtils.defaultString(next.getValueAsString()).contains(":")) {
        return true;
      }
    }
    return false;
  }


  public static String codeForAggregation(AggregationMode a) {
    switch (a) {
    case BUNDLED : return "b";
    case CONTAINED : return "c";
    case REFERENCED: return "r";
    default: return "?";
    }
  }

  public static  String hintForAggregation(AggregationMode a) {
    if (a != null)
      return a.getDefinition();
    else 
      return null;
  }


  private String checkPrepend(String corePath, String path) {
    if (pkp != null && pkp.prependLinks() && !(path.startsWith("http:") || path.startsWith("https:")))
      return corePath+path;
    else 
      return path;
  }


  private class ElementInStructure {

    private StructureDefinition source;
    private ElementDefinition element;

    public ElementInStructure(StructureDefinition source, ElementDefinition ed) {
      this.source = source;
      this.element = ed;
    }

    public StructureDefinition getSource() {
      return source;
    }

    public ElementDefinition getElement() {
      return element;
    }
    
  }
  private ElementInStructure getElementByName(List<ElementDefinition> elements, String contentReference, StructureDefinition source) {
    if (contentReference.contains("#")) {
      String url = contentReference.substring(0, contentReference.indexOf("#"));
      contentReference = contentReference.substring(contentReference.indexOf("#"));
      if (!url.equals(source.getUrl())) {
        source = context.fetchResource(StructureDefinition.class, url);
        if (source == null) {
          throw new FHIRException("Unable to resolve StructureDefinition "+url+" resolving content reference "+contentReference);
        }
        elements = source.getSnapshot().getElement();
      }
    } 
    for (ElementDefinition ed : elements) {
      if (("#"+ed.getPath()).equals(contentReference)) {
        return new ElementInStructure(source, ed);
      }
      if (("#"+ed.getId()).equals(contentReference)) {
        return new ElementInStructure(source, ed);
      }
    }
    throw new Error("getElementByName: can't find "+contentReference+" in "+elements.toString()+" from "+source.getUrl());
//    return null;
  }

  private ElementDefinitionResolution getElementById(StructureDefinition source, List<ElementDefinition> elements, String contentReference) {
    if (!contentReference.startsWith("#") && contentReference.contains("#")) {
      String url = contentReference.substring(0, contentReference.indexOf("#"));
      contentReference = contentReference.substring(contentReference.indexOf("#"));
      if (!url.equals(source.getUrl())){
        source = context.fetchResource(StructureDefinition.class, url);
        if (source == null) {
          return null;
        }
        elements = source.getSnapshot().getElement();
      }      
    }
    for (ElementDefinition ed : elements)
      if (ed.hasId() && ("#"+ed.getId()).equals(contentReference))
        return new ElementDefinitionResolution(source, ed);
    return null;
  }


  public static String describeExtensionContext(StructureDefinition ext) {
    StringBuilder b = new StringBuilder();
    b.append("Use on ");
    for (int i = 0; i < ext.getContext().size(); i++) {
      StructureDefinitionContextComponent ec = ext.getContext().get(i);
      if (i > 0) 
        b.append(i < ext.getContext().size() - 1 ? ", " : " or ");
      b.append(ec.getType().getDisplay());
      b.append(" ");
      b.append(ec.getExpression());
    }
    if (ext.hasContextInvariant()) {
      b.append(", with <a href=\"structuredefinition-definitions.html#StructureDefinition.contextInvariant\">Context Invariant</a> = ");
      boolean first = true;
      for (StringType s : ext.getContextInvariant()) {
        if (first)
          first = false;
        else
          b.append(", ");
        b.append("<code>"+s.getValue()+"</code>");
      }
    }
    return b.toString(); 
  }

  private String describeCardinality(ElementDefinition definition, ElementDefinition fallback, UnusedTracker tracker) {
    IntegerType min = definition.hasMinElement() ? definition.getMinElement() : new IntegerType();
    StringType max = definition.hasMaxElement() ? definition.getMaxElement() : new StringType();
    if (min.isEmpty() && fallback != null)
      min = fallback.getMinElement();
    if (max.isEmpty() && fallback != null)
      max = fallback.getMaxElement();

    tracker.used = !max.isEmpty() && !max.getValue().equals("0");

    if (min.isEmpty() && max.isEmpty())
      return null;
    else
      return (!min.hasValue() ? "" : Integer.toString(min.getValue())) + ".." + (!max.hasValue() ? "" : max.getValue());
  }

  private Cell genCardinality(HierarchicalTableGenerator gen, ElementDefinition definition, Row row, boolean hasDef, UnusedTracker tracker, ElementDefinition fallback) {
    IntegerType min = !hasDef ? new IntegerType() : definition.hasMinElement() ? definition.getMinElement() : new IntegerType();
    StringType max = !hasDef ? new StringType() : definition.hasMaxElement() ? definition.getMaxElement() : new StringType();
    if (min.isEmpty() && definition.getUserData(DERIVATION_POINTER) != null) {
      ElementDefinition base = (ElementDefinition) definition.getUserData(DERIVATION_POINTER);
      if (base.hasMinElement()) {
        min = base.getMinElement().copy();
        min.setUserData(DERIVATION_EQUALS, true);
      }
    }
    if (max.isEmpty() && definition.getUserData(DERIVATION_POINTER) != null) {
      ElementDefinition base = (ElementDefinition) definition.getUserData(DERIVATION_POINTER);
      if (base.hasMaxElement()) {
        max = base.getMaxElement().copy();
        max.setUserData(DERIVATION_EQUALS, true);
      }
    }
    if (min.isEmpty() && fallback != null)
      min = fallback.getMinElement();
    if (max.isEmpty() && fallback != null)
      max = fallback.getMaxElement();

    if (!max.isEmpty())
      tracker.used = !max.getValue().equals("0");

    Cell cell = gen.new Cell(null, null, null, null, null);
    row.getCells().add(cell);
    if (!min.isEmpty() || !max.isEmpty()) {
      cell.addPiece(checkForNoChange(min, gen.new Piece(null, !min.hasValue() ? "" : Integer.toString(min.getValue()), null)));
      cell.addPiece(checkForNoChange(min, max, gen.new Piece(null, "..", null)));
      cell.addPiece(checkForNoChange(max, gen.new Piece(null, !max.hasValue() ? "" : max.getValue(), null)));
    }
    return cell;
  }


  private Piece checkForNoChange(Element source, Piece piece) {
    if (source.hasUserData(DERIVATION_EQUALS)) {
      piece.addStyle("opacity: 0.5");
    }
    return piece;
  }

  private String checkForNoChange(Element source) {
    if (source.hasUserData(DERIVATION_EQUALS)) {
      return "opacity: 0.5";
    } else { 
      return null;
    }
  }


  private Piece applyAsUnchanged(Piece piece) {
    piece.addStyle("opacity: 0.5");
    return piece;
  }

  private String applyAsUnchanged() {
    return "opacity: 0.5";
  }


  private Piece checkForNoChange(Element src1, Element src2, Piece piece) {
    if (src1.hasUserData(DERIVATION_EQUALS) && src2.hasUserData(DERIVATION_EQUALS)) {
      piece.addStyle("opacity: 0.5");
    }
    return piece;
  }

  public XhtmlNode generateTable(String defFile, StructureDefinition profile, boolean diff, String imageFolder, boolean inlineGraphics, String profileBaseFileName, boolean snapshot, String corePath, String imagePath, 
      boolean logicalModel, boolean allInvariants, Set<String> outputTracker, boolean active, boolean mustSupport) throws IOException, FHIRException {
    assert(diff != snapshot);// check it's ok to get rid of one of these
    HierarchicalTableGenerator gen = new HierarchicalTableGenerator(imageFolder, inlineGraphics, true);
    gen.setTranslator(getTranslator());
    TableModel model = gen.initNormalTable(corePath, false, true, profile.getId()+(diff ? "d" : "s"), active);
    List<ElementDefinition> list = new ArrayList<>();
    if (diff)
      list.addAll(profile.getDifferential().getElement());
    else
      list.addAll(profile.getSnapshot().getElement());
    List<StructureDefinition> profiles = new ArrayList<StructureDefinition>();
    profiles.add(profile);
    if (list.isEmpty()) {
      ElementDefinition root = new ElementDefinition().setPath(profile.getType());
      root.setId(profile.getType());
      list.add(root);
    } else {
      if (list.get(0).getPath().contains(".")) {
        ElementDefinition root = new ElementDefinition().setPath(profile.getType());
        root.setId(profile.getType());
        list.add(0, root);
      }
    }
    if (diff) {
      insertMissingSparseElements(list);
    }
    genElement(defFile == null ? null : defFile+"#", gen, model.getRows(), list.get(0), list, profiles, diff, profileBaseFileName, null, snapshot, corePath, imagePath, true, logicalModel, profile.getDerivation() == TypeDerivationRule.CONSTRAINT && usesMustSupport(list), allInvariants, null, mustSupport);
    try {
      return gen.generate(model, imagePath, 0, outputTracker);
        } catch (org.hl7.fhir.exceptions.FHIRException e) {
      throw new FHIRException(context.formatMessage(I18nConstants.ERROR_GENERATING_TABLE_FOR_PROFILE__, profile.getUrl(), e.getMessage()), e);
        }
  }


  private void insertMissingSparseElements(List<ElementDefinition> list) {
    int i = 1;
    while (i < list.size()) {
      String[] pathCurrent = list.get(i).getPath().split("\\.");
      String[] pathLast = list.get(i-1).getPath().split("\\.");
      int firstDiff = 0; // the first entry must be a match
      while (firstDiff < pathCurrent.length && firstDiff < pathLast.length && pathCurrent[firstDiff].equals(pathLast[firstDiff])) {
        firstDiff++;
      }
      if (!(isSibling(pathCurrent, pathLast, firstDiff) || isChild(pathCurrent, pathLast, firstDiff))) {
        // now work backwards down to lastMatch inserting missing path nodes
        ElementDefinition parent = findParent(list, i, list.get(i).getPath());
        int parentDepth = Utilities.charCount(parent.getPath(), '.')+1;
        int childDepth =  Utilities.charCount(list.get(i).getPath(), '.')+1;
        if (childDepth > parentDepth + 1) {
          String basePath = parent.getPath();
          String baseId = parent.getId();
          for (int index = parentDepth; index >= firstDiff; index--) {
            String mtail = makeTail(pathCurrent, parentDepth, index);
            ElementDefinition root = new ElementDefinition().setPath(basePath+"."+mtail);
            root.setId(baseId+"."+mtail);
            list.add(i, root);
          }
        }
      } 
      i++;
    }
  }

  private ElementDefinition findParent(List<ElementDefinition> list, int i, String path) {
    while (i > 0 && !path.startsWith(list.get(i).getPath()+".")) {
      i--;
    }
    return list.get(i);
  }

  private boolean isSibling(String[] pathCurrent, String[] pathLast, int firstDiff) {
    return pathCurrent.length == pathLast.length && firstDiff == pathCurrent.length-1;
  }


  private boolean isChild(String[] pathCurrent, String[] pathLast, int firstDiff) {
    return pathCurrent.length == pathLast.length+1 && firstDiff == pathLast.length;
  }

  private String makeTail(String[] pathCurrent, int start, int index) {
    CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder(".");
    for (int i = start; i <= index; i++) {
      b.append(pathCurrent[i]);
    }
    return b.toString();
  }

  private String makePath(String[] pathCurrent, int index) {
    CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder(".");
    for (int i = 0; i <= index; i++) {
      b.append(pathCurrent[i]);
    }
    return b.toString();
  }


  public XhtmlNode generateGrid(String defFile, StructureDefinition profile, String imageFolder, boolean inlineGraphics, String profileBaseFileName, String corePath, String imagePath, Set<String> outputTracker) throws IOException, FHIRException {
    HierarchicalTableGenerator gen = new HierarchicalTableGenerator(imageFolder, inlineGraphics, true);
    gen.setTranslator(getTranslator());
    TableModel model = gen.initGridTable(corePath, profile.getId());
    List<ElementDefinition> list = profile.getSnapshot().getElement();
    List<StructureDefinition> profiles = new ArrayList<StructureDefinition>();
    profiles.add(profile);
    genGridElement(defFile == null ? null : defFile+"#", gen, model.getRows(), list.get(0), list, profiles, true, profileBaseFileName, null, corePath, imagePath, true, profile.getDerivation() == TypeDerivationRule.CONSTRAINT && usesMustSupport(list));
    try {
      return gen.generate(model, imagePath, 1, outputTracker);
    } catch (org.hl7.fhir.exceptions.FHIRException e) {
      throw new FHIRException(e.getMessage(), e);
    }
  }


  private boolean usesMustSupport(List<ElementDefinition> list) {
    for (ElementDefinition ed : list)
      if (ed.hasMustSupport() && ed.getMustSupport())
        return true;
    return false;
  }


  private Row genElement(String defPath, HierarchicalTableGenerator gen, List<Row> rows, ElementDefinition element, List<ElementDefinition> all, List<StructureDefinition> profiles, boolean showMissing, String profileBaseFileName, Boolean extensions, 
      boolean snapshot, String corePath, String imagePath, boolean root, boolean logicalModel, boolean isConstraintMode, boolean allInvariants, Row slicingRow, boolean mustSupport) throws IOException, FHIRException {
    Row originalRow = slicingRow;
    StructureDefinition profile = profiles == null ? null : profiles.get(profiles.size()-1);
    Row typesRow = null;
    
    List<ElementDefinition> children = getChildren(all, element);
//    if (!snapshot && isExtension && extensions != null && extensions != isExtension)
//      return;

    if (!onlyInformationIsMapping(all, element)) {
      Row row = gen.new Row();
      row.setAnchor(element.getPath());
      row.setColor(getRowColor(element, isConstraintMode));
      if (element.hasSlicing())
        row.setLineColor(1);
      else if (element.hasSliceName())
        row.setLineColor(2);
      else
        row.setLineColor(0);
      boolean hasDef = element != null;
      boolean ext = false;
      if (tail(element.getPath()).equals("extension")) {
        if (element.hasType() && element.getType().get(0).hasProfile() && extensionIsComplex(element.getType().get(0).getProfile().get(0).getValue()))
          row.setIcon("icon_extension_complex.png", HierarchicalTableGenerator.TEXT_ICON_EXTENSION_COMPLEX);
        else
          row.setIcon("icon_extension_simple.png", HierarchicalTableGenerator.TEXT_ICON_EXTENSION_SIMPLE);
        ext = true;
      } else if (tail(element.getPath()).equals("modifierExtension")) {
        if (element.hasType() && element.getType().get(0).hasProfile() && extensionIsComplex(element.getType().get(0).getProfile().get(0).getValue()))
          row.setIcon("icon_modifier_extension_complex.png", HierarchicalTableGenerator.TEXT_ICON_EXTENSION_COMPLEX);
        else
          row.setIcon("icon_modifier_extension_simple.png", HierarchicalTableGenerator.TEXT_ICON_EXTENSION_SIMPLE);
      } else if (!hasDef || element.getType().size() == 0) {
        if (root && context.getResourceNames().contains(profile.getType())) {
          row.setIcon("icon_resource.png", HierarchicalTableGenerator.TEXT_ICON_RESOURCE);
        } else {
          row.setIcon("icon_element.gif", HierarchicalTableGenerator.TEXT_ICON_ELEMENT);
        }
      } else if (hasDef && element.getType().size() > 1) {
        if (allAreReference(element.getType())) {
          row.setIcon("icon_reference.png", HierarchicalTableGenerator.TEXT_ICON_REFERENCE);
        } else {
          row.setIcon("icon_choice.gif", HierarchicalTableGenerator.TEXT_ICON_CHOICE);
          typesRow = row;
        }
      } else if (hasDef && element.getType().get(0).getWorkingCode() != null && element.getType().get(0).getWorkingCode().startsWith("@")) {
        row.setIcon("icon_reuse.png", HierarchicalTableGenerator.TEXT_ICON_REUSE);
      } else if (hasDef && isPrimitive(element.getType().get(0).getWorkingCode())) {
        row.setIcon("icon_primitive.png", HierarchicalTableGenerator.TEXT_ICON_PRIMITIVE);
      } else if (hasDef && element.getType().get(0).hasTarget()) {
        row.setIcon("icon_reference.png", HierarchicalTableGenerator.TEXT_ICON_REFERENCE);
      } else if (hasDef && isDataType(element.getType().get(0).getWorkingCode())) {
        row.setIcon("icon_datatype.gif", HierarchicalTableGenerator.TEXT_ICON_DATATYPE);
      } else if (hasDef && Utilities.existsInList(element.getType().get(0).getWorkingCode(), "Element", "BackboneElement")) {
        row.setIcon("icon_element.gif", HierarchicalTableGenerator.TEXT_ICON_ELEMENT);
      } else {
        row.setIcon("icon_resource.png", HierarchicalTableGenerator.TEXT_ICON_RESOURCE);
      }
      if (element.hasUserData("render.opaque")) {
        row.setOpacity("0.5");
      }
      UnusedTracker used = new UnusedTracker();
      String ref = defPath == null ? null : defPath + element.getId();
      String sName = tail(element.getPath());
      if (element.hasSliceName())
        sName = sName +":"+element.getSliceName();
      used.used = true;
      if (logicalModel && element.hasRepresentation(PropertyRepresentation.XMLATTR))
        sName = "@"+sName;
      Cell nc = genElementNameCell(gen, element, profileBaseFileName, snapshot, corePath, imagePath, root, logicalModel, allInvariants, profile, typesRow, row, hasDef, ext, used, ref, sName);
      genElementCells(gen, element, profileBaseFileName, snapshot, corePath, imagePath, root, logicalModel, allInvariants, profile, typesRow, row, hasDef, ext, used, ref, sName, nc, mustSupport, true);
      if (element.hasSlicing()) {
        if (standardExtensionSlicing(element)) {
          used.used = true; // doesn't matter whether we have a type, we're used if we're setting up slicing ... element.hasType() && element.getType().get(0).hasProfile();
          showMissing = false; //?
        } else {
          row.setIcon("icon_slice.png", HierarchicalTableGenerator.TEXT_ICON_SLICE);
          slicingRow = row;
          for (Cell cell : row.getCells())
            for (Piece p : cell.getPieces()) {
              p.addStyle("font-style: italic");
            }
        }
      } else if (element.hasSliceName()) {
        row.setIcon("icon_slice_item.png", HierarchicalTableGenerator.TEXT_ICON_SLICE_ITEM);
      }
      if (used.used || showMissing)
        rows.add(row);
      if (!used.used && !element.hasSlicing()) {
        for (Cell cell : row.getCells())
          for (Piece p : cell.getPieces()) {
            p.setStyle("text-decoration:line-through");
            p.setReference(null);
          }
      } else {
        if (slicingRow != originalRow && !children.isEmpty()) {
          // we've entered a slice; we're going to create a holder row for the slice children
          Row hrow = gen.new Row();
          hrow.setAnchor(element.getPath());
          hrow.setColor(getRowColor(element, isConstraintMode));
          hrow.setLineColor(1);
          hrow.setIcon("icon_element.gif", HierarchicalTableGenerator.TEXT_ICON_ELEMENT);
          hrow.getCells().add(gen.new Cell(null, null, sName+":All Slices", "", null));
          hrow.getCells().add(gen.new Cell());
          hrow.getCells().add(gen.new Cell());
          hrow.getCells().add(gen.new Cell());
          hrow.getCells().add(gen.new Cell(null, null, "Content/Rules for all slices", "", null));
          row.getSubRows().add(hrow);
          row = hrow;
        }
        if (typesRow != null && !children.isEmpty()) {
          // we've entered a typing slice; we're going to create a holder row for the all types children
          Row hrow = gen.new Row();
          hrow.setAnchor(element.getPath());
          hrow.setColor(getRowColor(element, isConstraintMode));
          hrow.setLineColor(1);
          hrow.setIcon("icon_element.gif", HierarchicalTableGenerator.TEXT_ICON_ELEMENT);
          hrow.getCells().add(gen.new Cell(null, null, sName+":All Types", "", null));
          hrow.getCells().add(gen.new Cell());
          hrow.getCells().add(gen.new Cell());
          hrow.getCells().add(gen.new Cell());
          hrow.getCells().add(gen.new Cell(null, null, "Content/Rules for all Types", "", null));
          row.getSubRows().add(hrow);
          row = hrow;
        }
          
        Row currRow = row;
        List<ElementChoiceGroup> groups = readChoices(element, children);
        boolean isExtension = Utilities.existsInList(tail(element.getPath()), "extension", "modifierExtension");
        for (ElementDefinition child : children) {
          if (!child.hasSliceName()) {
            currRow = row; 
          }
          Row childRow = chooseChildRowByGroup(gen, currRow, groups, child, element, isConstraintMode);
          
          if (logicalModel || !child.getPath().endsWith(".id") || (child.getPath().endsWith(".id") && (profile != null) && (profile.getDerivation() == TypeDerivationRule.CONSTRAINT))) {  
            currRow = genElement(defPath, gen, childRow.getSubRows(), child, all, profiles, showMissing, profileBaseFileName, isExtension, snapshot, corePath, imagePath, false, logicalModel, isConstraintMode, allInvariants, currRow, mustSupport);
          }
        }
//        if (!snapshot && (extensions == null || !extensions))
//          for (ElementDefinition child : children)
//            if (child.getPath().endsWith(".extension") || child.getPath().endsWith(".modifierExtension"))
//              genElement(defPath, gen, row.getSubRows(), child, all, profiles, showMissing, profileBaseFileName, true, false, corePath, imagePath, false, logicalModel, isConstraintMode, allInvariants);
      }
      if (typesRow != null) {
        makeChoiceRows(typesRow.getSubRows(), element, gen, corePath, profileBaseFileName, mustSupport);
      }
    }
    return slicingRow;
  }

  private Row chooseChildRowByGroup(HierarchicalTableGenerator gen, Row row, List<ElementChoiceGroup> groups, ElementDefinition element, ElementDefinition parent, boolean isConstraintMode) {
    String name = tail(element.getPath());
    for (ElementChoiceGroup grp : groups) {
      if (grp.getElements().contains(name)) {
        if (grp.getRow() == null) {
          grp.setRow(makeChoiceElementRow(gen, row, grp, parent, isConstraintMode));
        }
        return grp.getRow();
      }
    }
    return row;
  }

  private Row makeChoiceElementRow(HierarchicalTableGenerator gen, Row prow, ElementChoiceGroup grp, ElementDefinition parent, boolean isConstraintMode) {
    Row row = gen.new Row();
    row.setAnchor(parent.getPath()+"-"+grp.getName());
    row.setColor(getRowColor(parent, isConstraintMode));
    row.setLineColor(1);
    row.setIcon("icon_choice.gif", HierarchicalTableGenerator.TEXT_ICON_CHOICE);
    row.getCells().add(gen.new Cell(null, null, "(Choice of one)", "", null));
    row.getCells().add(gen.new Cell());
    row.getCells().add(gen.new Cell(null, null, (grp.mandatory ? "1" : "0")+"..1", "", null));
    row.getCells().add(gen.new Cell());
    row.getCells().add(gen.new Cell());
    prow.getSubRows().add(row);
    return row;
  }

  public Cell genElementNameCell(HierarchicalTableGenerator gen, ElementDefinition element, String profileBaseFileName, boolean snapshot, String corePath,
      String imagePath, boolean root, boolean logicalModel, boolean allInvariants, StructureDefinition profile, Row typesRow, Row row, boolean hasDef,
      boolean ext, UnusedTracker used, String ref, String sName) throws IOException {
    String hint = "";
    hint = checkAdd(hint, (element.hasSliceName() ? translate("sd.table", "Slice")+" "+element.getSliceName() : ""));
    if (hasDef && element.hasDefinition()) {
      hint = checkAdd(hint, (hasDef && element.hasSliceName() ? ": " : ""));
      hint = checkAdd(hint, !hasDef ? null : gt(element.getDefinitionElement()));
    }
    if (element.hasSlicing()) {
      sName = "Slices for "+sName;
    }
    Cell left = gen.new Cell(null, ref, sName, hint, null);
    row.getCells().add(left);
    return left;
  }

  public List<Cell> genElementCells(HierarchicalTableGenerator gen, ElementDefinition element, String profileBaseFileName, boolean snapshot, String corePath,
      String imagePath, boolean root, boolean logicalModel, boolean allInvariants, StructureDefinition profile, Row typesRow, Row row, boolean hasDef,
      boolean ext, UnusedTracker used, String ref, String sName, Cell nameCell, boolean mustSupport, boolean allowSubRows) throws IOException {
    List<Cell> res = new ArrayList<>();
    Cell gc = gen.new Cell();
    row.getCells().add(gc);
    res.add(gc);
    if (element != null && element.getIsModifier()) {
      checkForNoChange(element.getIsModifierElement(), gc.addStyledText(translate("sd.table", "This element is a modifier element"), "?!", null, null, null, false));
    }
    if (element != null && element.getMustSupport()) {
      checkForNoChange(element.getMustSupportElement(), gc.addStyledText(translate("sd.table", "This element must be supported"), "S", "white", "red", null, false));
    }
    if (element != null && element.getIsSummary()) {
      checkForNoChange(element.getIsSummaryElement(), gc.addStyledText(translate("sd.table", "This element is included in summaries"), "\u03A3", null, null, null, false));
    }
    if (element != null && (hasNonBaseConstraints(element.getConstraint()) || hasNonBaseConditions(element.getCondition()))) {
      gc.addStyledText(translate("sd.table", "This element has or is affected by some invariants ("+listConstraintsAndConditions(element)+")"), "I", null, null, null, false);
    }

    ExtensionContext extDefn = null;
    if (ext) {
      if (element != null && element.getType().size() == 1 && element.getType().get(0).hasProfile()) {
        String eurl = element.getType().get(0).getProfile().get(0).getValue();
        extDefn = locateExtension(StructureDefinition.class, eurl);
        if (extDefn == null) {
          res.add(genCardinality(gen, element, row, hasDef, used, null));
          res.add(addCell(row, gen.new Cell(null, null, "?gen-e1? "+element.getType().get(0).getProfile(), null, null)));
          res.add(generateDescription(gen, row, element, (ElementDefinition) element.getUserData(DERIVATION_POINTER), used.used, profile == null ? "" : profile.getUrl(), eurl, profile, corePath, imagePath, root, logicalModel, allInvariants, snapshot, mustSupport, allowSubRows));
        } else {
          String name = urltail(eurl);
          nameCell.getPieces().get(0).setText(name);
          // left.getPieces().get(0).setReference((String) extDefn.getExtensionStructure().getTag("filename"));
          nameCell.getPieces().get(0).setHint(translate("sd.table", "Extension URL")+" = "+extDefn.getUrl());
          res.add(genCardinality(gen, element, row, hasDef, used, extDefn.getElement()));
          ElementDefinition valueDefn = extDefn.getExtensionValueDefinition();
          if (valueDefn != null && !"0".equals(valueDefn.getMax()))
            res.add(genTypes(gen, row, valueDefn, profileBaseFileName, profile, corePath, imagePath, root, mustSupport));
           else // if it's complex, we just call it nothing
              // genTypes(gen, row, extDefn.getSnapshot().getElement().get(0), profileBaseFileName, profile);
            res.add(addCell(row, gen.new Cell(null, null, "("+translate("sd.table", "Complex")+")", null, null)));
          res.add(generateDescription(gen, row, element, extDefn.getElement(), used.used, null, extDefn.getUrl(), profile, corePath, imagePath, root, logicalModel, allInvariants, valueDefn, snapshot, mustSupport, allowSubRows));
        }
      } else {
        res.add(genCardinality(gen, element, row, hasDef, used, null));
        if ("0".equals(element.getMax()))
          res.add(addCell(row, gen.new Cell()));            
        else
          res.add(genTypes(gen, row, element, profileBaseFileName, profile, corePath, imagePath, root, mustSupport));
        res.add(generateDescription(gen, row, element, (ElementDefinition) element.getUserData(DERIVATION_POINTER), used.used, null, null, profile, corePath, imagePath, root, logicalModel, allInvariants, snapshot, mustSupport, allowSubRows));
      }
    } else {
      res.add(genCardinality(gen, element, row, hasDef, used, null));
      if (hasDef && !"0".equals(element.getMax()) && typesRow == null)
        res.add(genTypes(gen, row, element, profileBaseFileName, profile, corePath, imagePath, root, mustSupport));
      else
        res.add(addCell(row, gen.new Cell()));
      res.add(generateDescription(gen, row, element, (ElementDefinition) element.getUserData(DERIVATION_POINTER), used.used, null, null, profile, corePath, imagePath, root, logicalModel, allInvariants, snapshot, mustSupport, allowSubRows));
    }
    return res;
  }


    private Cell addCell(Row row, Cell cell) {
    row.getCells().add(cell);
    return (cell);
  }

  private String checkAdd(String src, String app) {
    return app == null ? src : src + app;
  }

  private boolean hasNonBaseConditions(List<IdType> conditions) {
    for (IdType c : conditions) {
      if (!isBaseCondition(c)) {
        return true;
      }
    }
    return false;
  }


  private boolean hasNonBaseConstraints(List<ElementDefinitionConstraintComponent> constraints) {
    for (ElementDefinitionConstraintComponent c : constraints) {
      if (!isBaseConstraint(c)) {
        return true;
      }
    }
    return false;
  }

  private String listConstraintsAndConditions(ElementDefinition element) {
    CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder();
    for (ElementDefinitionConstraintComponent con : element.getConstraint()) {
      if (!isBaseConstraint(con)) {
        b.append(con.getKey());
      }
    }
    for (IdType id : element.getCondition()) {
      if (!isBaseCondition(id)) {
        b.append(id.asStringValue());
      }
    }
    return b.toString();
  }

  private boolean isBaseCondition(IdType c) {
    String key = c.asStringValue();
    return key.startsWith("ele-") || key.startsWith("res-") || key.startsWith("ext-") || key.startsWith("dom-") || key.startsWith("dr-");
  }

  private boolean isBaseConstraint(ElementDefinitionConstraintComponent con) {
    String key = con.getKey();
    return key.startsWith("ele-") || key.startsWith("res-") || key.startsWith("ext-") || key.startsWith("dom-") || key.startsWith("dr-");
  }

  private void makeChoiceRows(List<Row> subRows, ElementDefinition element, HierarchicalTableGenerator gen, String corePath, String profileBaseFileName, boolean mustSupportMode) {
    // create a child for each choice
    for (TypeRefComponent tr : element.getType()) {
      if (!mustSupportMode || allTypesMustSupport(element) || isMustSupport(tr)) {
        Row choicerow = gen.new Row();
        String t = tr.getWorkingCode();
        if (isReference(t)) {
          choicerow.getCells().add(gen.new Cell(null, null, tail(element.getPath()).replace("[x]", Utilities.capitalize(t)), null, null));
          choicerow.getCells().add(gen.new Cell());
          choicerow.getCells().add(gen.new Cell(null, null, "", null, null));
          choicerow.setIcon("icon_reference.png", HierarchicalTableGenerator.TEXT_ICON_REFERENCE);
          Cell c = gen.new Cell();
          choicerow.getCells().add(c);
          if (ADD_REFERENCE_TO_TABLE) {
            if (tr.getWorkingCode().equals("canonical"))
              c.getPieces().add(gen.new Piece(corePath+"datatypes.html#canonical", "canonical", null));
            else
              c.getPieces().add(gen.new Piece(corePath+"references.html#Reference", "Reference", null));
            if (!mustSupportMode && isMustSupportDirect(tr) && element.getMustSupport()) {
              c.addPiece(gen.new Piece(null, " ", null));
              c.addStyledText(translate("sd.table", "This type must be supported"), "S", "white", "red", null, false);
            }
            c.getPieces().add(gen.new Piece(null, "(", null));
          }
          boolean first = true;
          for (CanonicalType rt : tr.getTargetProfile()) {
            if (!mustSupportMode || allProfilesMustSupport(tr.getTargetProfile()) || isMustSupport(rt)) {
              if (!first)
                c.getPieces().add(gen.new Piece(null, " | ", null));
              genTargetLink(gen, profileBaseFileName, corePath, c, tr, rt.getValue());
              if (!mustSupportMode && isMustSupport(rt) && element.getMustSupport()) {
                c.addPiece(gen.new Piece(null, " ", null));
                c.addStyledText(translate("sd.table", "This target must be supported"), "S", "white", "red", null, false);
              }
              first = false;
            }
          }
          if (first) {
            c.getPieces().add(gen.new Piece(null, "Any", null));
          }

          if (ADD_REFERENCE_TO_TABLE) { 
            c.getPieces().add(gen.new Piece(null, ")", null));
          }

        } else {
          StructureDefinition sd = context.fetchTypeDefinition(t);
          if (sd == null) {
            System.out.println("Unable to find "+t);
            sd = context.fetchTypeDefinition(t);
          } else if (sd.getKind() == StructureDefinitionKind.PRIMITIVETYPE) {
            choicerow.getCells().add(gen.new Cell(null, null, tail(element.getPath()).replace("[x]",  Utilities.capitalize(t)), sd.getDescription(), null));
            choicerow.getCells().add(gen.new Cell());
            choicerow.getCells().add(gen.new Cell(null, null, "", null, null));
            choicerow.setIcon("icon_primitive.png", HierarchicalTableGenerator.TEXT_ICON_PRIMITIVE);
            Cell c = gen.new Cell(null, corePath+"datatypes.html#"+t, sd.getType(), null, null);
            choicerow.getCells().add(c);
            if (!mustSupportMode && isMustSupport(tr) && element.getMustSupport()) {
              c.addPiece(gen.new Piece(null, " ", null));
              c.addStyledText(translate("sd.table", "This type must be supported"), "S", "white", "red", null, false);
            }
          } else {
            choicerow.getCells().add(gen.new Cell(null, null, tail(element.getPath()).replace("[x]",  Utilities.capitalize(t)), sd.getDescription(), null));
            choicerow.getCells().add(gen.new Cell());
            choicerow.getCells().add(gen.new Cell(null, null, "", null, null));
            choicerow.setIcon("icon_datatype.gif", HierarchicalTableGenerator.TEXT_ICON_DATATYPE);
            Cell c = gen.new Cell(null, pkp.getLinkFor(corePath, t), sd.getType(), null, null);
            choicerow.getCells().add(c);
            if (!mustSupportMode && isMustSupport(tr) && element.getMustSupport()) {
              c.addPiece(gen.new Piece(null, " ", null));
              c.addStyledText(translate("sd.table", "This type must be supported"), "S", "white", "red", null, false);
            }
          }
          if (tr.hasProfile()) {
            Cell typeCell = choicerow.getCells().get(3);
            typeCell.addPiece(gen.new Piece(null, "(", null));
            boolean first = true;
            for (CanonicalType pt : tr.getProfile()) {
              if (!mustSupportMode || allProfilesMustSupport(tr.getProfile()) || isMustSupport(pt)) {
                if (first) first = false; else typeCell.addPiece(gen.new Piece(null, " | ", null));
                StructureDefinition psd = context.fetchResource(StructureDefinition.class, pt.getValue());
                if (psd == null)
                  typeCell.addPiece(gen.new Piece(null, "?gen-e2?", null));
                else
                  typeCell.addPiece(gen.new Piece(psd.getUserString("path"), psd.getName(), psd.present()));
                if (!mustSupportMode && isMustSupport(pt) && element.getMustSupport()) {
                  typeCell.addPiece(gen.new Piece(null, " ", null));
                  typeCell.addStyledText(translate("sd.table", "This profile must be supported"), "S", "white", "red", null, false);
                }
              }
            }
            typeCell.addPiece(gen.new Piece(null, ")", null));
          }
        }    
        choicerow.getCells().add(gen.new Cell());
        subRows.add(choicerow);
      }
    }
  }

  private boolean isReference(String t) {
    return t.equals("Reference") || t.equals("canonical"); 
  }  



  private void genGridElement(String defPath, HierarchicalTableGenerator gen, List<Row> rows, ElementDefinition element, List<ElementDefinition> all, List<StructureDefinition> profiles, boolean showMissing, String profileBaseFileName, Boolean extensions, String corePath, String imagePath, boolean root, boolean isConstraintMode) throws IOException, FHIRException {
    StructureDefinition profile = profiles == null ? null : profiles.get(profiles.size()-1);
    String s = tail(element.getPath());
    List<ElementDefinition> children = getChildren(all, element);
    boolean isExtension = (s.equals("extension") || s.equals("modifierExtension"));

    if (!onlyInformationIsMapping(all, element)) {
      Row row = gen.new Row();
      row.setAnchor(element.getPath());
      row.setColor(getRowColor(element, isConstraintMode));
      if (element.hasSlicing())
        row.setLineColor(1);
      else if (element.hasSliceName())
        row.setLineColor(2);
      else
        row.setLineColor(0);
      boolean hasDef = element != null;
      String ref = defPath == null ? null : defPath + element.getId();
      UnusedTracker used = new UnusedTracker();
      used.used = true;
      Cell left = gen.new Cell();
      if (element.getType().size() == 1 && element.getType().get(0).isPrimitive())
        left.getPieces().add(gen.new Piece(ref, "\u00A0\u00A0" + s, !hasDef ? null : gt(element.getDefinitionElement())).addStyle("font-weight:bold"));
      else
        left.getPieces().add(gen.new Piece(ref, "\u00A0\u00A0" + s, !hasDef ? null : gt(element.getDefinitionElement())));
      if (element.hasSliceName()) {
        left.getPieces().add(gen.new Piece("br"));
        String indent = StringUtils.repeat('\u00A0', 1+2*(element.getPath().split("\\.").length));
        left.getPieces().add(gen.new Piece(null, indent + "("+element.getSliceName() + ")", null));
      }
      row.getCells().add(left);

      ExtensionContext extDefn = null;
      genCardinality(gen, element, row, hasDef, used, null);
      if (hasDef && !"0".equals(element.getMax()))
        genTypes(gen, row, element, profileBaseFileName, profile, corePath, imagePath, root, false);
      else
        row.getCells().add(gen.new Cell());
      generateGridDescription(gen, row, element, null, used.used, null, null, profile, corePath, imagePath, root, null);
/*      if (element.hasSlicing()) {
        if (standardExtensionSlicing(element)) {
          used.used = element.hasType() && element.getType().get(0).hasProfile();
          showMissing = false;
        } else {
          row.setIcon("icon_slice.png", HierarchicalTableGenerator.TEXT_ICON_SLICE);
          row.getCells().get(2).getPieces().clear();
          for (Cell cell : row.getCells())
            for (Piece p : cell.getPieces()) {
              p.addStyle("font-style: italic");
            }
        }
      }*/
      rows.add(row);
      for (ElementDefinition child : children)
        if (child.getMustSupport())
          genGridElement(defPath, gen, row.getSubRows(), child, all, profiles, showMissing, profileBaseFileName, isExtension, corePath, imagePath, false, isConstraintMode);
    }
  }


  private ExtensionContext locateExtension(Class<StructureDefinition> class1, String value)  {
    if (value.contains("#")) {
      StructureDefinition ext = context.fetchResource(StructureDefinition.class, value.substring(0, value.indexOf("#")));
      if (ext == null)
        return null;
      String tail = value.substring(value.indexOf("#")+1);
      ElementDefinition ed = null;
      for (ElementDefinition ted : ext.getSnapshot().getElement()) {
        if (tail.equals(ted.getSliceName())) {
          ed = ted;
          return new ExtensionContext(ext, ed);
        }
      }
      return null;
    } else {
      StructureDefinition ext = context.fetchResource(StructureDefinition.class, value);
      if (ext == null)
        return null;
      else 
        return new ExtensionContext(ext, ext.getSnapshot().getElement().get(0));
    }
  }


  private boolean extensionIsComplex(String value) {
    if (value.contains("#")) {
      StructureDefinition ext = context.fetchResource(StructureDefinition.class, value.substring(0, value.indexOf("#")));
    if (ext == null)
      return false;
      String tail = value.substring(value.indexOf("#")+1);
      ElementDefinition ed = null;
      for (ElementDefinition ted : ext.getSnapshot().getElement()) {
        if (tail.equals(ted.getSliceName())) {
          ed = ted;
          break;
        }
      }
      if (ed == null)
        return false;
      int i = ext.getSnapshot().getElement().indexOf(ed);
      int j = i+1;
      while (j < ext.getSnapshot().getElement().size() && !ext.getSnapshot().getElement().get(j).getPath().equals(ed.getPath()))
        j++;
      return j - i > 5;
    } else {
      StructureDefinition ext = context.fetchResource(StructureDefinition.class, value);
      return ext != null && ext.getSnapshot().getElement().size() > 5;
    }
  }


  public String getRowColor(ElementDefinition element, boolean isConstraintMode) {
    switch (element.getUserInt(UD_ERROR_STATUS)) {
    case STATUS_HINT: return ROW_COLOR_HINT;
    case STATUS_WARNING: return ROW_COLOR_WARNING;
    case STATUS_ERROR: return ROW_COLOR_ERROR;
    case STATUS_FATAL: return ROW_COLOR_FATAL;
    }
    if (isConstraintMode && !element.getMustSupport() && !element.getIsModifier() && element.getPath().contains("."))
      return null; // ROW_COLOR_NOT_MUST_SUPPORT;
    else
      return null;
  }


  private String urltail(String path) {
    if (path.contains("#"))
      return path.substring(path.lastIndexOf('#')+1);
    if (path.contains("/"))
      return path.substring(path.lastIndexOf('/')+1);
    else
      return path;

  }

  private boolean standardExtensionSlicing(ElementDefinition element) {
    String t = tail(element.getPath());
    return (t.equals("extension") || t.equals("modifierExtension"))
          && element.getSlicing().getRules() != SlicingRules.CLOSED && element.getSlicing().getDiscriminator().size() == 1 && element.getSlicing().getDiscriminator().get(0).getPath().equals("url") && element.getSlicing().getDiscriminator().get(0).getType().equals(DiscriminatorType.VALUE);
  }

  private Cell generateDescription(HierarchicalTableGenerator gen, Row row, ElementDefinition definition, ElementDefinition fallback, boolean used, String baseURL, String url, StructureDefinition profile, String corePath, String imagePath, boolean root, boolean logicalModel, boolean allInvariants, boolean snapshot, boolean mustSupportOnly, boolean allowSubRows) throws IOException, FHIRException {
    return generateDescription(gen, row, definition, fallback, used, baseURL, url, profile, corePath, imagePath, root, logicalModel, allInvariants, null, snapshot, mustSupportOnly, allowSubRows);
  }
  
  private Cell generateDescription(HierarchicalTableGenerator gen, Row row, ElementDefinition definition, ElementDefinition fallback, boolean used, String baseURL, String url, StructureDefinition profile, String corePath, String imagePath, boolean root, boolean logicalModel, boolean allInvariants, ElementDefinition valueDefn, boolean snapshot, boolean mustSupportOnly, boolean allowSubRows) throws IOException, FHIRException {
    Cell c = gen.new Cell();
    row.getCells().add(c);

    if (used) {
      if (logicalModel && ToolingExtensions.hasExtension(profile, "http://hl7.org/fhir/StructureDefinition/elementdefinition-namespace")) {
        if (root) {
          c.getPieces().add(gen.new Piece(null, translate("sd.table", "XML Namespace")+": ", null).addStyle("font-weight:bold"));
          c.getPieces().add(gen.new Piece(null, ToolingExtensions.readStringExtension(profile, "http://hl7.org/fhir/StructureDefinition/elementdefinition-namespace"), null));        
        } else if (!root && ToolingExtensions.hasExtension(definition, "http://hl7.org/fhir/StructureDefinition/elementdefinition-namespace") && 
            !ToolingExtensions.readStringExtension(definition, "http://hl7.org/fhir/StructureDefinition/elementdefinition-namespace").equals(ToolingExtensions.readStringExtension(profile, "http://hl7.org/fhir/StructureDefinition/elementdefinition-namespace"))) {
          c.getPieces().add(gen.new Piece(null, translate("sd.table", "XML Namespace")+": ", null).addStyle("font-weight:bold"));
          c.getPieces().add(gen.new Piece(null, ToolingExtensions.readStringExtension(definition, "http://hl7.org/fhir/StructureDefinition/elementdefinition-namespace"), null));        
        }
      }
      if (root) {
        if (profile != null && profile.getAbstract()) {
          if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
          c.addPiece(gen.new Piece(null, "This is an abstract profile", null));          
        }
      }
      if (definition.getPath().endsWith("url") && definition.hasFixed()) {
        c.getPieces().add(checkForNoChange(definition.getFixed(), gen.new Piece(null, "\""+buildJson(definition.getFixed())+"\"", null).addStyle("color: darkgreen")));
      } else {
        if (definition != null && definition.hasShort()) {
          if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
          c.addPiece(checkForNoChange(definition.getShortElement(), gen.new Piece(null, gt(definition.getShortElement()), null)));
        } else if (fallback != null && fallback.hasShort()) {
          if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
          c.addPiece(gen.new Piece(null, gt(fallback.getShortElement()), null).addStyle("opacity: 0.5"));
        }
        if (url != null) {
          if (!c.getPieces().isEmpty()) 
            c.addPiece(gen.new Piece("br"));
          String fullUrl = url.startsWith("#") ? baseURL+url : url;
          StructureDefinition ed = context.fetchResource(StructureDefinition.class, url);
          String ref = null;
          String ref2 = null;
          String fixedUrl = null;
          if (ed != null) {
            String p = ed.getUserString("path");
            if (p != null) {
              ref = p.startsWith("http:") || igmode ? p : Utilities.pathURL(corePath, p);
            }             
            fixedUrl = getFixedUrl(ed);
            if (fixedUrl != null) {// if its null, we guess that it's not a profiled extension?
              if (fixedUrl.equals(url))
                fixedUrl = null;
              else {
                StructureDefinition ed2 = context.fetchResource(StructureDefinition.class, fixedUrl);
                if (ed2 != null) {
                  String p2 = ed2.getUserString("path");
                  if (p2 != null) {
                    ref2 = p2.startsWith("http:") || igmode ? p2 : Utilities.pathURL(corePath, p2);
                  }                              
                }
              }
            }
          }
          if (fixedUrl == null) {
            c.getPieces().add(gen.new Piece(null, translate("sd.table", "URL")+": ", null).addStyle("font-weight:bold"));
            c.getPieces().add(gen.new Piece(ref, fullUrl, null));
          } else { 
            // reference to a profile take on the extension show the base URL
            c.getPieces().add(gen.new Piece(null, translate("sd.table", "URL")+": ", null).addStyle("font-weight:bold"));
            c.getPieces().add(gen.new Piece(ref2, fixedUrl, null));
            c.getPieces().add(gen.new Piece(null, translate("sd.table", " profiled by ")+" ", null).addStyle("font-weight:bold"));
            c.getPieces().add(gen.new Piece(ref, fullUrl, null));
          
          }
        }

        if (definition.hasSlicing()) {
          if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
          c.getPieces().add(gen.new Piece(null, translate("sd.table", "Slice")+": ", null).addStyle("font-weight:bold"));
          c.getPieces().add(gen.new Piece(null, describeSlice(definition.getSlicing()), null));
        }
        if (!definition.getPath().contains(".") && ToolingExtensions.hasExtension(profile, ToolingExtensions.EXT_BINDING_STYLE)) {
          if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
          c.getPieces().add(gen.new Piece(null, translate("sd.table", "Binding")+": ", null).addStyle("font-weight:bold"));
          c.getPieces().add(gen.new Piece(null, "This type can be bound to a value set using the ", null));
          c.getPieces().add(gen.new Piece(null, ToolingExtensions.readStringExtension(profile, ToolingExtensions.EXT_BINDING_STYLE), null));
          c.getPieces().add(gen.new Piece(null, " binding style", null));            
          
        }
        if (definition.hasExtension(ToolingExtensions.EXT_XML_NAME)) {
          if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
          if (definition.hasExtension(ToolingExtensions.EXT_XML_NAMESPACE)) {
            c.getPieces().add(gen.new Piece(null, translate("sd.table", "XML")+": ", null).addStyle("font-weight:bold"));
            c.getPieces().add(gen.new Piece(null, definition.getExtensionString(ToolingExtensions.EXT_XML_NAME), null));
            c.getPieces().add(gen.new Piece(null, " (", null));
            c.getPieces().add(gen.new Piece(null, definition.getExtensionString(ToolingExtensions.EXT_XML_NAMESPACE), null));
            c.getPieces().add(gen.new Piece(null, ")", null));            
          } else {
            c.getPieces().add(gen.new Piece(null, translate("sd.table", "XML Element Name")+": ", null).addStyle("font-weight:bold"));
            c.getPieces().add(gen.new Piece(null, definition.getExtensionString(ToolingExtensions.EXT_XML_NAME), null));
          }            
        } else if (definition.hasExtension(ToolingExtensions.EXT_XML_NAMESPACE)) {
          if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
          c.getPieces().add(gen.new Piece(null, translate("sd.table", "XML Namespace")+": ", null).addStyle("font-weight:bold"));
          c.getPieces().add(gen.new Piece(null, definition.getExtensionString(ToolingExtensions.EXT_XML_NAMESPACE), null));          
        }
        if (definition != null) {
          ElementDefinitionBindingComponent binding = null;
          if (valueDefn != null && valueDefn.hasBinding() && !valueDefn.getBinding().isEmpty())
            binding = makeUnifiedBinding(valueDefn.getBinding(), valueDefn);
          else if (definition.hasBinding())
            binding = makeUnifiedBinding(definition.getBinding(), definition);
          if (binding!=null && !binding.isEmpty()) {
            if (!c.getPieces().isEmpty()) 
              c.addPiece(gen.new Piece("br"));
            BindingResolution br = pkp == null ? makeNullBr(binding) : pkp.resolveBinding(profile, binding, definition.getPath());
            c.getPieces().add(checkForNoChange(binding, gen.new Piece(null, translate("sd.table", "Binding")+": ", null).addStyle("font-weight:bold")));
              c.getPieces().add(checkForNoChange(binding.getValueSetElement(), gen.new Piece(br.url == null ? null : Utilities.isAbsoluteUrl(br.url) || !pkp.prependLinks() ? br.url : corePath+br.url, br.display, null)));
            if (binding.hasStrength()) {
              c.getPieces().add(checkForNoChange(binding.getStrengthElement(), gen.new Piece(null, " (", null)));
              c.getPieces().add(checkForNoChange(binding.getStrengthElement(), gen.new Piece(corePath+"terminologies.html#"+binding.getStrength().toCode(), egt(binding.getStrengthElement()), binding.getStrength().getDefinition())));                            
              c.getPieces().add(checkForNoChange(binding.getStrengthElement(), gen.new Piece(null, ")", null)));
            }
            if (binding.hasExtension(ToolingExtensions.EXT_MAX_VALUESET)) {
              br = pkp == null ? makeNullBr(binding) : pkp.resolveBinding(profile, ToolingExtensions.readStringExtension(binding, ToolingExtensions.EXT_MAX_VALUESET), definition.getPath());
              c.addPiece(gen.new Piece("br"));
              c.getPieces().add(checkForNoChange(binding, gen.new Piece(corePath+"extension-elementdefinition-maxvalueset.html", translate("sd.table", "Max Binding")+": ", "Max Value Set Extension").addStyle("font-weight:bold")));             
              c.getPieces().add(checkForNoChange(binding, gen.new Piece(br.url == null ? null : Utilities.isAbsoluteUrl(br.url) || !pkp.prependLinks() ? br.url : corePath+br.url, br.display, null)));
            }
            if (binding.hasExtension(ToolingExtensions.EXT_MIN_VALUESET)) {
              br = pkp.resolveBinding(profile, ToolingExtensions.readStringExtension(binding, ToolingExtensions.EXT_MIN_VALUESET), definition.getPath());
              c.addPiece(gen.new Piece("br"));
              c.getPieces().add(checkForNoChange(binding, gen.new Piece(corePath+"extension-elementdefinition-minvalueset.html", translate("sd.table", "Min Binding")+": ", "Min Value Set Extension").addStyle("font-weight:bold")));             
              c.getPieces().add(checkForNoChange(binding, gen.new Piece(br.url == null ? null : Utilities.isAbsoluteUrl(br.url) || !pkp.prependLinks() ? br.url : corePath+br.url, br.display, null)));
            }
            if (binding.hasDescription() && MarkDownProcessor.isSimpleMarkdown(binding.getDescription())) {
              c.getPieces().add(gen.new Piece(null, ": ", null));
              c.addMarkdownNoPara(PublicationHacker.fixBindingDescriptions(context, binding.getDescriptionElement()).asStringValue(), checkForNoChange(PublicationHacker.fixBindingDescriptions(context, binding.getDescriptionElement())));
            } 
            if (binding.hasExtension(ToolingExtensions.EXT_BINDING_ADDITIONAL)) {
              c.addPiece(gen.new Piece("br"));
              c.getPieces().add(checkForNoChange(binding, gen.new Piece(null, translate("sd.table", "Additional Bindings")+": ", null).addStyle("font-weight:bold")));
              for (Extension ext : binding.getExtensionsByUrl(ToolingExtensions.EXT_BINDING_ADDITIONAL)) {
                 renderAdditionalBinding(gen, c, ext); 
              }              
            }
          }
          for (ElementDefinitionConstraintComponent inv : definition.getConstraint()) {
            if (!inv.hasSource() || profile == null || inv.getSource().equals(profile.getUrl()) || allInvariants) {
              if (!c.getPieces().isEmpty()) 
                c.addPiece(gen.new Piece("br"));
              c.getPieces().add(checkForNoChange(inv, gen.new Piece(null, inv.getKey()+": ", null).addStyle("font-weight:bold")));
              c.getPieces().add(checkForNoChange(inv, gen.new Piece(null, gt(inv.getHumanElement()), null)));
            }
          }
          if ((definition.hasBase() && "*".equals(definition.getBase().getMax())) || (definition.hasMax() && "*".equals(definition.getMax()))) {
            if (c.getPieces().size() > 0)
              c.addPiece(gen.new Piece("br"));
            if (definition.hasOrderMeaning()) {
              c.getPieces().add(gen.new Piece(null, "This repeating element order: "+definition.getOrderMeaning(), null));
            } else {
              // don't show this, this it's important: c.getPieces().add(gen.new Piece(null, "This repeating element has no defined order", null));
            }           
          }
          if (definition.hasFixed()) {
            if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
            c.getPieces().add(checkForNoChange(definition.getFixed(), gen.new Piece(null, translate("sd.table", "Fixed Value")+": ", null).addStyle("font-weight:bold")));
            if (!useTableForFixedValues || !allowSubRows || definition.getFixed().isPrimitive()) {
              String s = buildJson(definition.getFixed());
              String link = null;
              if (Utilities.isAbsoluteUrl(s))
                link = pkp.getLinkForUrl(corePath, s);
              c.getPieces().add(checkForNoChange(definition.getFixed(), gen.new Piece(link, s, null).addStyle("color: darkgreen")));
            } else {
              c.getPieces().add(checkForNoChange(definition.getFixed(), gen.new Piece(null, "As shown", null).addStyle("color: darkgreen")));
              genFixedValue(gen, row, definition.getFixed(), snapshot, false, corePath, false);
            }
            if (isCoded(definition.getFixed()) && !hasDescription(definition.getFixed())) {
              Piece p = describeCoded(gen, definition.getFixed());
              if (p != null)
                c.getPieces().add(p);
            }
          } else if (definition.hasPattern()) {
            if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
            c.getPieces().add(checkForNoChange(definition.getPattern(), gen.new Piece(null, translate("sd.table", "Required Pattern")+": ", null).addStyle("font-weight:bold")));
            if (!useTableForFixedValues || !allowSubRows || definition.getPattern().isPrimitive())
              c.getPieces().add(checkForNoChange(definition.getPattern(), gen.new Piece(null, buildJson(definition.getPattern()), null).addStyle("color: darkgreen")));
            else {
              c.getPieces().add(checkForNoChange(definition.getPattern(), gen.new Piece(null, "At least the following", null).addStyle("color: darkgreen")));
              genFixedValue(gen, row, definition.getPattern(), snapshot, true, corePath, mustSupportOnly);
            }
          } else if (definition.hasExample()) {
            for (ElementDefinitionExampleComponent ex : definition.getExample()) {
              if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
              c.getPieces().add(checkForNoChange(ex, gen.new Piece(null, translate("sd.table", "Example")+("".equals("General")? "" : " "+ex.getLabel())+": ", null).addStyle("font-weight:bold")));
              c.getPieces().add(checkForNoChange(ex, gen.new Piece(null, buildJson(ex.getValue()), null).addStyle("color: darkgreen")));
            }
          }
          if (definition.hasMaxLength() && definition.getMaxLength()!=0) {
            if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
            c.getPieces().add(checkForNoChange(definition.getMaxLengthElement(), gen.new Piece(null, "Max Length: ", null).addStyle("font-weight:bold")));
            c.getPieces().add(checkForNoChange(definition.getMaxLengthElement(), gen.new Piece(null, Integer.toString(definition.getMaxLength()), null).addStyle("color: darkgreen")));
          }
          if (profile != null) {
            for (StructureDefinitionMappingComponent md : profile.getMapping()) {
              if (md.hasExtension(ToolingExtensions.EXT_TABLE_NAME)) {
                ElementDefinitionMappingComponent map = null;
                for (ElementDefinitionMappingComponent m : definition.getMapping()) 
                  if (m.getIdentity().equals(md.getIdentity()))
                    map = m;
                if (map != null) {
                  for (int i = 0; i<definition.getMapping().size(); i++){
                    c.addPiece(gen.new Piece("br"));
                    c.getPieces().add(gen.new Piece(null, ToolingExtensions.readStringExtension(md, ToolingExtensions.EXT_TABLE_NAME)+": " + map.getMap(), null));
                  }
                }
              }
            }
          }
        }
      }
    }
    return c;
  }

  private void renderAdditionalBinding(HierarchicalTableGenerator gen, Cell c, Extension ext) {
    // <nsbp>2 <sp> purpose <sp> value-set-link ([context]) {documentation}
    String purpose = ext.getExtensionString("purpose");
    String valueSet = ext.getExtensionString("valueSet");
    String doco = ext.getExtensionString("documentation");
    UsageContext usage = (ext.hasExtension("usage")) ? ext.getExtensionByUrl("usage").getValueUsageContext() : null;
//    
//    purpose: code - defines how the binding is used
//    usage : UsageContext - defines the contexts in which this binding is used for it's purpose
//    valueSet : canonical(ValueSet)
//    documentation : markdown
//    !!
//    c.getPieces().add(checkForNoChange(inv, gen.new Piece(null, inv.getKey()+": ", null).addStyle("font-weight:bold")));
//    c.getPieces().add(checkForNoChange(inv, gen.new Piece(null, gt(inv.getHumanElement()), null)));

  }

  private BindingResolution makeNullBr(ElementDefinitionBindingComponent binding) {
    BindingResolution br = new BindingResolution();
    br.url = "http://none.none/none";
    br.display = "todo";
    return br;
  }

  private ElementDefinitionBindingComponent makeUnifiedBinding(ElementDefinitionBindingComponent binding, ElementDefinition element) {
    if (!element.hasUserData(DERIVATION_POINTER)) {
      return binding;
    }
    ElementDefinition base = (ElementDefinition) element.getUserData(DERIVATION_POINTER);
    if (!base.hasBinding()) {
      return binding;
    }
    ElementDefinitionBindingComponent o = base.getBinding();
    ElementDefinitionBindingComponent b = new ElementDefinitionBindingComponent();
    b.setUserData(DERIVATION_POINTER, o);
    if (binding.hasValueSet()) {
      b.setValueSet(binding.getValueSet());
    } else if (o.hasValueSet()) {
      b.setValueSet(o.getValueSet());
      b.getValueSetElement().setUserData(DERIVATION_EQUALS, o.getValueSetElement());
    }
    if (binding.hasStrength()) {
      b.setStrength(binding.getStrength());
    } else if (o.hasStrength()) {
      b.setStrength(o.getStrength());
      b.getStrengthElement().setUserData(DERIVATION_EQUALS, o.getStrengthElement());
    }
    if (binding.hasDescription()) {
      b.setDescription(binding.getDescription());
    } else if (o.hasDescription()) {
      b.setDescription(o.getDescription());
      b.getDescriptionElement().setUserData(DERIVATION_EQUALS, o.getDescriptionElement());
    }
    return b;
  }

  private void genFixedValue(HierarchicalTableGenerator gen, Row erow, DataType value, boolean snapshot, boolean pattern, String corePath, boolean skipnoValue) {
    String ref = pkp.getLinkFor(corePath, value.fhirType());
    if (ref != null && ref.contains(".html")) {
      ref = ref.substring(0, ref.indexOf(".html"))+"-definitions.html#";
    } else {
      ref = "?gen-fv?";
    }
    StructureDefinition sd = context.fetchTypeDefinition(value.fhirType());

    for (org.hl7.fhir.r5.model.Property t : value.children()) {
      if (t.getValues().size() > 0 || snapshot) {
        ElementDefinition ed = findElementDefinition(sd, t.getName());
        if (t.getValues().size() == 0 || (t.getValues().size() == 1 && t.getValues().get(0).isEmpty())) {
          if (!skipnoValue) {
            Row row = gen.new Row();
            erow.getSubRows().add(row);
            Cell c = gen.new Cell();
            row.getCells().add(c);
            c.addPiece(gen.new Piece((ed.getBase().getPath().equals(ed.getPath()) ? ref+ed.getPath() : corePath+(VersionUtilities.isR5Ver(context.getVersion()) ? "types-definitions.html#"+ed.getBase().getPath() : "element-definitions.html#"+ed.getBase().getPath())), t.getName(), null));
            c = gen.new Cell();
            row.getCells().add(c);
            c.addPiece(gen.new Piece(null, null, null));
            c = gen.new Cell();
            row.getCells().add(c);
            if (!pattern) {
              c.addPiece(gen.new Piece(null, "0..0", null));
              row.setIcon("icon_fixed.gif", "Fixed Value" /*HierarchicalTableGenerator.TEXT_ICON_FIXED*/);
            } else if (isPrimitive(t.getTypeCode())) {
              row.setIcon("icon_primitive.png", HierarchicalTableGenerator.TEXT_ICON_PRIMITIVE);
              c.addPiece(gen.new Piece(null, "0.."+(t.getMaxCardinality() == 2147483647 ? "*": Integer.toString(t.getMaxCardinality())), null));
            } else if (isReference(t.getTypeCode())) { 
              row.setIcon("icon_reference.png", HierarchicalTableGenerator.TEXT_ICON_REFERENCE);
              c.addPiece(gen.new Piece(null, "0.."+(t.getMaxCardinality() == 2147483647 ? "*": Integer.toString(t.getMaxCardinality())), null));
            } else { 
              row.setIcon("icon_datatype.gif", HierarchicalTableGenerator.TEXT_ICON_DATATYPE);
              c.addPiece(gen.new Piece(null, "0.."+(t.getMaxCardinality() == 2147483647 ? "*": Integer.toString(t.getMaxCardinality())), null));
            }
            c = gen.new Cell();
            row.getCells().add(c);
            if (t.getTypeCode().contains("(")) {
              String tc = t.getTypeCode();
              String tn = tc.substring(0, tc.indexOf("("));
              c.addPiece(gen.new Piece(pkp.getLinkFor(corePath, tn), tn, null));
              c.addPiece(gen.new Piece(null, "(", null));
              String[] p = tc.substring(tc.indexOf("(")+1, tc.indexOf(")")).split("\\|");
              for (String s : p) {
                c.addPiece(gen.new Piece(pkp.getLinkFor(corePath, s), s, null));
              }
              c.addPiece(gen.new Piece(null, ")", null));            
            } else {
              c.addPiece(gen.new Piece(pkp.getLinkFor(corePath, t.getTypeCode()), t.getTypeCode(), null));
            }
            c = gen.new Cell();
            c.addPiece(gen.new Piece(null, ed.getShort(), null));
            row.getCells().add(c);
          }
        } else {
          for (Base b : t.getValues()) {
            Row row = gen.new Row();
            erow.getSubRows().add(row);
            row.setIcon("icon_fixed.gif", "Fixed Value" /*HierarchicalTableGenerator.TEXT_ICON_FIXED*/);

            Cell c = gen.new Cell();
            row.getCells().add(c);
            c.addPiece(gen.new Piece((ed.getBase().getPath().equals(ed.getPath()) ? ref+ed.getPath() : (VersionUtilities.isThisOrLater("4.1", context.getVersion()) ? corePath+"types-definitions.html#"+ed.getBase().getPath() : corePath+"element-definitions.html#"+ed.getBase().getPath())), t.getName(), null));

            c = gen.new Cell();
            row.getCells().add(c);
            c.addPiece(gen.new Piece(null, null, null));

            c = gen.new Cell();
            row.getCells().add(c);
            if (pattern)
              c.addPiece(gen.new Piece(null, "1.."+(t.getMaxCardinality() == 2147483647 ? "*" : Integer.toString(t.getMaxCardinality())), null));
            else
              c.addPiece(gen.new Piece(null, "1..1", null));

            c = gen.new Cell();
            row.getCells().add(c);
            if (b.fhirType().contains("(")) {
              String tc = b.fhirType();
              String tn = tc.substring(0, tc.indexOf("("));
              c.addPiece(gen.new Piece(pkp.getLinkFor(corePath, tn), tn, null));
              c.addPiece(gen.new Piece(null, "(", null));
              String[] p = tc.substring(tc.indexOf("(")+1, tc.indexOf(")")).split("\\|");
              for (String s : p) {
                c.addPiece(gen.new Piece(pkp.getLinkFor(corePath, s), s, null));
              }
              c.addPiece(gen.new Piece(null, ")", null));            
            } else {
              c.addPiece(gen.new Piece(pkp.getLinkFor(corePath, b.fhirType()), b.fhirType(), null));
            }

            if (b.isPrimitive()) {
              c = gen.new Cell();
              row.getCells().add(c);
              c.addPiece(gen.new Piece(null, ed.getShort(), null));
              c.addPiece(gen.new Piece("br"));
              c.getPieces().add(gen.new Piece(null, "Fixed Value: ", null).addStyle("font-weight: bold"));
              String s = b.primitiveValue();
              // ok. let's see if we can find a relevant link for this
              String link = null;
              if (Utilities.isAbsoluteUrl(s)) {
                link = pkp.getLinkForUrl(corePath, s);
              }
              c.getPieces().add(gen.new Piece(link, s, null).addStyle("color: darkgreen"));
            } else {
              c = gen.new Cell();
              row.getCells().add(c);
              c.addPiece(gen.new Piece(null, ed.getShort(), null));
              c.addPiece(gen.new Piece("br"));
              c.getPieces().add(gen.new Piece(null, "Fixed Value: ", null).addStyle("font-weight: bold"));
              c.getPieces().add(gen.new Piece(null, "(complex)", null).addStyle("color: darkgreen"));
              genFixedValue(gen, row, (DataType) b, snapshot, pattern, corePath, skipnoValue);
            }
          }
        }
      }
    }
  }


  private ElementDefinition findElementDefinition(StructureDefinition sd, String name) {
    String path = sd.getType()+"."+name;
    for (ElementDefinition ed : sd.getSnapshot().getElement()) {
      if (ed.getPath().equals(path))
        return ed;
    }
    throw new FHIRException(context.formatMessage(I18nConstants.UNABLE_TO_FIND_ELEMENT_, path));
  }


  private String getFixedUrl(StructureDefinition sd) {
    for (ElementDefinition ed : sd.getSnapshot().getElement()) {
      if (ed.getPath().equals("Extension.url")) {
        if (ed.hasFixed() && ed.getFixed() instanceof UriType)
          return ed.getFixed().primitiveValue();
      }
    }
    return null;
  }


  private Piece describeCoded(HierarchicalTableGenerator gen, DataType fixed) {
    if (fixed instanceof Coding) {
      Coding c = (Coding) fixed;
      ValidationResult vr = context.validateCode(terminologyServiceOptions , c.getSystem(), c.getVersion(), c.getCode(), c.getDisplay());
      if (vr.getDisplay() != null)
        return gen.new Piece(null, " ("+vr.getDisplay()+")", null).addStyle("color: darkgreen");
    } else if (fixed instanceof CodeableConcept) {
      CodeableConcept cc = (CodeableConcept) fixed;
      for (Coding c : cc.getCoding()) {
        ValidationResult vr = context.validateCode(terminologyServiceOptions, c.getSystem(), c.getVersion(), c.getCode(), c.getDisplay());
        if (vr.getDisplay() != null)
          return gen.new Piece(null, " ("+vr.getDisplay()+")", null).addStyle("color: darkgreen");
      }
    }
    return null;
  }


  private boolean hasDescription(DataType fixed) {
    if (fixed instanceof Coding) {
      return ((Coding) fixed).hasDisplay();
    } else if (fixed instanceof CodeableConcept) {
      CodeableConcept cc = (CodeableConcept) fixed;
      if (cc.hasText())
        return true;
      for (Coding c : cc.getCoding())
        if (c.hasDisplay())
         return true;
    } // (fixed instanceof CodeType) || (fixed instanceof Quantity);
    return false;
  }


  private boolean isCoded(DataType fixed) {
    return (fixed instanceof Coding) || (fixed instanceof CodeableConcept) || (fixed instanceof CodeType) || (fixed instanceof Quantity);
  }


  private Cell generateGridDescription(HierarchicalTableGenerator gen, Row row, ElementDefinition definition, ElementDefinition fallback, boolean used, String baseURL, String url, StructureDefinition profile, String corePath, String imagePath, boolean root, ElementDefinition valueDefn) throws IOException, FHIRException {
    Cell c = gen.new Cell();
    row.getCells().add(c);

    if (used) {
      if (definition.hasContentReference()) {
        ElementInStructure ed = getElementByName(profile.getSnapshot().getElement(), definition.getContentReference(), profile);
        if (ed == null)
          c.getPieces().add(gen.new Piece(null, "Unknown reference to "+definition.getContentReference(), null));
        else {
          if (ed.getSource() == profile) {
            c.getPieces().add(gen.new Piece("#"+ed.getElement().getPath(), "See "+ed.getElement().getPath(), null));
          } else {
            c.getPieces().add(gen.new Piece(ed.getSource().getUserData("path")+"#"+ed.getElement().getPath(), "See "+ed.getSource().getType()+"."+ed.getElement().getPath(), null));
          }          
        }
      }
      if (definition.getPath().endsWith("url") && definition.hasFixed()) {
        c.getPieces().add(checkForNoChange(definition.getFixed(), gen.new Piece(null, "\""+buildJson(definition.getFixed())+"\"", null).addStyle("color: darkgreen")));
      } else {
        if (url != null) {
          if (!c.getPieces().isEmpty()) 
            c.addPiece(gen.new Piece("br"));
          String fullUrl = url.startsWith("#") ? baseURL+url : url;
          StructureDefinition ed = context.fetchResource(StructureDefinition.class, url);
          String ref = null;
          if (ed != null) {
            String p = ed.getUserString("path");
            if (p != null) {
              ref = p.startsWith("http:") || igmode ? p : Utilities.pathURL(corePath, p);
            }
          }
          c.getPieces().add(gen.new Piece(null, "URL: ", null).addStyle("font-weight:bold"));
          c.getPieces().add(gen.new Piece(ref, fullUrl, null));
        }

        if (definition.hasSlicing()) {
          if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
          c.getPieces().add(gen.new Piece(null, "Slice: ", null).addStyle("font-weight:bold"));
          c.getPieces().add(gen.new Piece(null, describeSlice(definition.getSlicing()), null));
        }
        if (definition != null) {
          ElementDefinitionBindingComponent binding = null;
          if (valueDefn != null && valueDefn.hasBinding() && !valueDefn.getBinding().isEmpty())
            binding = valueDefn.getBinding();
          else if (definition.hasBinding())
            binding = definition.getBinding();
          if (binding!=null && !binding.isEmpty()) {
            if (!c.getPieces().isEmpty()) 
              c.addPiece(gen.new Piece("br"));
            BindingResolution br = pkp.resolveBinding(profile, binding, definition.getPath());
            c.getPieces().add(checkForNoChange(binding, gen.new Piece(null, "Binding: ", null).addStyle("font-weight:bold")));
            c.getPieces().add(checkForNoChange(binding, gen.new Piece(br.url == null ? null : Utilities.isAbsoluteUrl(br.url) || !pkp.prependLinks() ? br.url : corePath+br.url, br.display, null)));
            if (binding.hasStrength()) {
              c.getPieces().add(checkForNoChange(binding, gen.new Piece(null, " (", null)));
              c.getPieces().add(checkForNoChange(binding, gen.new Piece(corePath+"terminologies.html#"+binding.getStrength().toCode(), binding.getStrength().toCode(), binding.getStrength().getDefinition())));              c.getPieces().add(gen.new Piece(null, ")", null));
            }
            if (binding.hasDescription() && MarkDownProcessor.isSimpleMarkdown(binding.getDescription())) {
              c.getPieces().add(gen.new Piece(null, ": ", null));
              c.addMarkdownNoPara(PublicationHacker.fixBindingDescriptions(context, binding.getDescriptionElement()).asStringValue());
            }
          }
          for (ElementDefinitionConstraintComponent inv : definition.getConstraint()) {
            if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
            c.getPieces().add(checkForNoChange(inv, gen.new Piece(null, inv.getKey()+": ", null).addStyle("font-weight:bold")));
            if (inv.getHumanElement().hasExtension("http://hl7.org/fhir/StructureDefinition/rendering-markdown")) {
              c.addMarkdown(inv.getHumanElement().getExtensionString("http://hl7.org/fhir/StructureDefinition/rendering-markdown"));
            } else {
              c.getPieces().add(checkForNoChange(inv, gen.new Piece(null, inv.getHuman(), null)));
            }
          }
          if (definition.hasFixed()) {
            if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
            c.getPieces().add(checkForNoChange(definition.getFixed(), gen.new Piece(null, "Fixed Value: ", null).addStyle("font-weight:bold")));
            String s = buildJson(definition.getFixed());
            String link = null;
            if (Utilities.isAbsoluteUrl(s))
              link = pkp.getLinkForUrl(corePath, s);
            c.getPieces().add(checkForNoChange(definition.getFixed(), gen.new Piece(link, s, null).addStyle("color: darkgreen")));
          } else if (definition.hasPattern()) {
            if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
            c.getPieces().add(checkForNoChange(definition.getPattern(), gen.new Piece(null, "Required Pattern: ", null).addStyle("font-weight:bold")));
            c.getPieces().add(checkForNoChange(definition.getPattern(), gen.new Piece(null, buildJson(definition.getPattern()), null).addStyle("color: darkgreen")));
          } else if (definition.hasExample()) {
            for (ElementDefinitionExampleComponent ex : definition.getExample()) {
              if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
              c.getPieces().add(checkForNoChange(ex, gen.new Piece(null, "Example'"+("".equals("General")? "" : " "+ex.getLabel()+"'")+": ", null).addStyle("font-weight:bold")));
              c.getPieces().add(checkForNoChange(ex, gen.new Piece(null, buildJson(ex.getValue()), null).addStyle("color: darkgreen")));
            }
          }
          if (definition.hasMaxLength() && definition.getMaxLength()!=0) {
            if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
            c.getPieces().add(checkForNoChange(definition.getMaxLengthElement(), gen.new Piece(null, "Max Length: ", null).addStyle("font-weight:bold")));
            c.getPieces().add(checkForNoChange(definition.getMaxLengthElement(), gen.new Piece(null, Integer.toString(definition.getMaxLength()), null).addStyle("color: darkgreen")));
          }
          if (profile != null) {
            for (StructureDefinitionMappingComponent md : profile.getMapping()) {
              if (md.hasExtension(ToolingExtensions.EXT_TABLE_NAME)) {
                ElementDefinitionMappingComponent map = null;
                for (ElementDefinitionMappingComponent m : definition.getMapping()) 
                  if (m.getIdentity().equals(md.getIdentity()))
                    map = m;
                if (map != null) {
                  for (int i = 0; i<definition.getMapping().size(); i++){
                    c.addPiece(gen.new Piece("br"));
                    c.getPieces().add(gen.new Piece(null, ToolingExtensions.readStringExtension(md, ToolingExtensions.EXT_TABLE_NAME)+": " + map.getMap(), null));
                  }
                }
              }
            }
          }
          if (definition.hasDefinition()) {
            if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
            c.getPieces().add(gen.new Piece(null, "Definition: ", null).addStyle("font-weight:bold"));
            c.addPiece(gen.new Piece("br"));
            c.addMarkdown(definition.getDefinition());
//            c.getPieces().add(checkForNoChange(definition.getCommentElement(), gen.new Piece(null, definition.getComment(), null)));
          }
          if (definition.getComment()!=null) {
            if (!c.getPieces().isEmpty()) { c.addPiece(gen.new Piece("br")); }
            c.getPieces().add(gen.new Piece(null, "Comments: ", null).addStyle("font-weight:bold"));
            c.addPiece(gen.new Piece("br"));
            c.addMarkdown(definition.getComment());
//            c.getPieces().add(checkForNoChange(definition.getCommentElement(), gen.new Piece(null, definition.getComment(), null)));
          }
        }
      }
    }
    return c;
  }



  private String buildJson(DataType value) throws IOException {
    if (value instanceof PrimitiveType)
      return ((PrimitiveType) value).asStringValue();

    IParser json = context.newJsonParser();
    return json.composeString(value, null);
  }


  public String describeSlice(ElementDefinitionSlicingComponent slicing) {
    return translate("sd.table", "%s, %s by %s", slicing.getOrdered() ? translate("sd.table", "Ordered") : translate("sd.table", "Unordered"), describe(slicing.getRules()), commas(slicing.getDiscriminator()));
  }

  private String commas(List<ElementDefinitionSlicingDiscriminatorComponent> list) {
    CommaSeparatedStringBuilder c = new CommaSeparatedStringBuilder();
    for (ElementDefinitionSlicingDiscriminatorComponent id : list)
      c.append((id.hasType() ? id.getType().toCode() : "??")+":"+id.getPath());
    return c.toString();
  }


  private String describe(SlicingRules rules) {
    if (rules == null)
      return translate("sd.table", "Unspecified");
    switch (rules) {
    case CLOSED : return translate("sd.table", "Closed");
    case OPEN : return translate("sd.table", "Open");
    case OPENATEND : return translate("sd.table", "Open At End");
    default:
      return "?gen-sr?";
    }
  }

  private boolean onlyInformationIsMapping(List<ElementDefinition> list, ElementDefinition e) {
    return (!e.hasSliceName() && !e.hasSlicing() && (onlyInformationIsMapping(e))) &&
        getChildren(list, e).isEmpty();
  }

  private boolean onlyInformationIsMapping(ElementDefinition d) {
    return !d.hasShort() && !d.hasDefinition() &&
        !d.hasRequirements() && !d.getAlias().isEmpty() && !d.hasMinElement() &&
        !d.hasMax() && !d.getType().isEmpty() && !d.hasContentReference() &&
        !d.hasExample() && !d.hasFixed() && !d.hasMaxLengthElement() &&
        !d.getCondition().isEmpty() && !d.getConstraint().isEmpty() && !d.hasMustSupportElement() &&
        !d.hasBinding();
  }

  private boolean allAreReference(List<TypeRefComponent> types) {
    for (TypeRefComponent t : types) {
      if (!t.hasTarget())
        return false;
    }
    return true;
  }

  private List<ElementDefinition> getChildren(List<ElementDefinition> all, ElementDefinition element) {
    List<ElementDefinition> result = new ArrayList<ElementDefinition>();
    int i = all.indexOf(element)+1;
    while (i < all.size() && all.get(i).getPath().length() > element.getPath().length()) {
      if ((all.get(i).getPath().substring(0, element.getPath().length()+1).equals(element.getPath()+".")) && !all.get(i).getPath().substring(element.getPath().length()+1).contains("."))
        result.add(all.get(i));
      i++;
    }
    return result;
  }

  private String tail(String path) {
    if (path.contains("."))
      return path.substring(path.lastIndexOf('.')+1);
    else
      return path;
  }

  private boolean isDataType(String value) {
    StructureDefinition sd = context.fetchTypeDefinition(value);
    if (sd == null) // might be running before all SDs are available
      return Utilities.existsInList(value, "Address", "Age", "Annotation", "Attachment", "CodeableConcept", "Coding", "ContactPoint", "Count", "Distance", "Duration", "HumanName", "Identifier", "Money", "Period", "Quantity", "Range", "Ratio", "Reference", "SampledData", "Signature", "Timing", 
            "ContactDetail", "Contributor", "DataRequirement", "Expression", "ParameterDefinition", "RelatedArtifact", "TriggerDefinition", "UsageContext");
    else 
      return sd.getKind() == StructureDefinitionKind.COMPLEXTYPE && sd.getDerivation() == TypeDerivationRule.SPECIALIZATION;
  }

  private boolean isConstrainedDataType(String value) {
    StructureDefinition sd = context.fetchTypeDefinition(value);
    if (sd == null) // might be running before all SDs are available
      return Utilities.existsInList(value, "SimpleQuantity", "MoneyQuantity");
    else 
      return sd.getKind() == StructureDefinitionKind.COMPLEXTYPE && sd.getDerivation() == TypeDerivationRule.CONSTRAINT;
  }

  private String baseType(String value) {
    StructureDefinition sd = context.fetchTypeDefinition(value);
    if (sd != null) // might be running before all SDs are available
      return sd.getType();
    if (Utilities.existsInList(value, "SimpleQuantity", "MoneyQuantity"))
      return "Quantity";
    throw new Error(context.formatMessage(I18nConstants.INTERNAL_ERROR___TYPE_NOT_KNOWN_, value));
  }


  public boolean isPrimitive(String value) {
    StructureDefinition sd = context.fetchTypeDefinition(value);
    if (sd == null) // might be running before all SDs are available
      return Utilities.existsInList(value, "base64Binary", "boolean", "canonical", "code", "date", "dateTime", "decimal", "id", "instant", "integer", "integer64", "markdown", "oid", "positiveInt", "string", "time", "unsignedInt", "uri", "url", "uuid");
    else 
      return sd.getKind() == StructureDefinitionKind.PRIMITIVETYPE;
  }

//  private static String listStructures(StructureDefinition p) {
//    StringBuilder b = new StringBuilder();
//    boolean first = true;
//    for (ProfileStructureComponent s : p.getStructure()) {
//      if (first)
//        first = false;
//      else
//        b.append(", ");
//      if (pkp != null && pkp.hasLinkFor(s.getType()))
//        b.append("<a href=\""+pkp.getLinkFor(s.getType())+"\">"+s.getType()+"</a>");
//      else
//        b.append(s.getType());
//    }
//    return b.toString();
//  }


  public StructureDefinition getProfile(StructureDefinition source, String url) {
        StructureDefinition profile = null;
        String code = null;
        if (url.startsWith("#")) {
                profile = source;
                code = url.substring(1);
        } else if (context != null) {
                String[] parts = url.split("\\#");
                profile = context.fetchResource(StructureDefinition.class, parts[0]);
      code = parts.length == 1 ? null : parts[1];
        }         
        if (profile == null)
                return null;
        if (code == null)
                return profile;
        for (Resource r : profile.getContained()) {
                if (r instanceof StructureDefinition && r.getId().equals(code))
                        return (StructureDefinition) r;
        }
        return null;
  }



  public static class ElementDefinitionHolder {
    private String name;
    private ElementDefinition self;
    private int baseIndex = 0;
    private List<ElementDefinitionHolder> children;
    private boolean placeHolder = false;

    public ElementDefinitionHolder(ElementDefinition self, boolean isPlaceholder) {
      super();
      this.self = self;
      this.name = self.getPath();
      this.placeHolder = isPlaceholder;
      children = new ArrayList<ElementDefinitionHolder>();      
    }

    public ElementDefinitionHolder(ElementDefinition self) {
      this(self, false);
    }

    public ElementDefinition getSelf() {
      return self;
    }

    public List<ElementDefinitionHolder> getChildren() {
      return children;
    }

    public int getBaseIndex() {
      return baseIndex;
    }

    public void setBaseIndex(int baseIndex) {
      this.baseIndex = baseIndex;
    }

    public boolean isPlaceHolder() {
      return this.placeHolder;
    }

    @Override
    public String toString() {
      if (self.hasSliceName())
        return self.getPath()+"("+self.getSliceName()+")";
      else
        return self.getPath();
    }
  }

  public static class ElementDefinitionComparer implements Comparator<ElementDefinitionHolder> {

    private boolean inExtension;
    private List<ElementDefinition> snapshot;
    private int prefixLength;
    private String base;
    private String name;
    private Set<String> errors = new HashSet<String>();

    public ElementDefinitionComparer(boolean inExtension, List<ElementDefinition> snapshot, String base, int prefixLength, String name) {
      this.inExtension = inExtension;
      this.snapshot = snapshot;
      this.prefixLength = prefixLength;
      this.base = base;
      if (Utilities.isAbsoluteUrl(base)) {
        this.base = urlTail(base);
      }
      this.name = name;
    }

    @Override
    public int compare(ElementDefinitionHolder o1, ElementDefinitionHolder o2) {
      if (o1.getBaseIndex() == 0)
        o1.setBaseIndex(find(o1.getSelf().getPath(), true));
      if (o2.getBaseIndex() == 0)
        o2.setBaseIndex(find(o2.getSelf().getPath(), true));
      return o1.getBaseIndex() - o2.getBaseIndex();
    }

    private int find(String path, boolean mandatory) {
      String op = path;
      int lc = 0;
      String actual = base+path.substring(prefixLength);
      for (int i = 0; i < snapshot.size(); i++) {
        String p = snapshot.get(i).getPath();
        if (p.equals(actual)) {
          return i;
        }
        if (p.endsWith("[x]") && actual.startsWith(p.substring(0, p.length()-3)) && !(actual.endsWith("[x]")) && !actual.substring(p.length()-3).contains(".")) {
          return i;
        }
        if (actual.endsWith("[x]") && p.startsWith(actual.substring(0, actual.length()-3)) && !p.substring(actual.length()-3).contains(".")) {
          return i;
        }
        if (path.startsWith(p+".") && snapshot.get(i).hasContentReference()) {
          String ref = snapshot.get(i).getContentReference();
          if (ref.substring(1, 2).toUpperCase().equals(ref.substring(1,2))) {
            actual = base+(ref.substring(1)+"."+path.substring(p.length()+1)).substring(prefixLength);
            path = actual;
          } else if (ref.startsWith("http:")) {
            actual = base+(ref.substring(ref.indexOf("#")+1)+"."+path.substring(p.length()+1)).substring(prefixLength);
            path = actual;            
          } else {
            // Older versions of FHIR (e.g. 2016May) had reference of the style #parameter instead of #Parameters.parameter, so we have to handle that
            actual = base+(path.substring(0,  path.indexOf(".")+1) + ref.substring(1)+"."+path.substring(p.length()+1)).substring(prefixLength);
            path = actual;
          }
            
          i = 0;
          lc++;
          if (lc > MAX_RECURSION_LIMIT)
            throw new Error("Internal recursion detection: find() loop path recursion > "+MAX_RECURSION_LIMIT+" - check paths are valid (for path "+path+"/"+op+")");
        }
      }
      if (mandatory) {
        if (prefixLength == 0)
          errors.add("Differential contains path "+path+" which is not found in the in base "+name);
        else
          errors.add("Differential contains path "+path+" which is actually "+actual+", which is not found in the in base "+name);
      }
      return 0;
    }

    public void checkForErrors(List<String> errorList) {
      if (errors.size() > 0) {
//        CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder();
//        for (String s : errors)
//          b.append("StructureDefinition "+name+": "+s);
//        throw new DefinitionException(b.toString());
        for (String s : errors)
          if (s.startsWith("!"))
            errorList.add("!StructureDefinition "+name+": "+s.substring(1));
          else
            errorList.add("StructureDefinition "+name+": "+s);
      }
    }
  }


  public void sortDifferential(StructureDefinition base, StructureDefinition diff, String name, List<String> errors, boolean errorIfChanges) throws FHIRException  {
    List<ElementDefinition> original = new ArrayList<>();
    original.addAll(diff.getDifferential().getElement());
    final List<ElementDefinition> diffList = diff.getDifferential().getElement();
    int lastCount = diffList.size();
    // first, we move the differential elements into a tree
    if (diffList.isEmpty())
      return;
    
    ElementDefinitionHolder edh = null;
    int i = 0;
    if (diffList.get(0).getPath().contains(".")) {
      String newPath = diffList.get(0).getPath().split("\\.")[0];
      ElementDefinition e = new ElementDefinition(newPath);
      edh = new ElementDefinitionHolder(e, true);
    } else {
      edh = new ElementDefinitionHolder(diffList.get(0));
      i = 1;
    }

    boolean hasSlicing = false;
    List<String> paths = new ArrayList<String>(); // in a differential, slicing may not be stated explicitly
    for(ElementDefinition elt : diffList) {
      if (elt.hasSlicing() || paths.contains(elt.getPath())) {
        hasSlicing = true;
        break;
      }
      paths.add(elt.getPath());
    }
    if(!hasSlicing) {
      // if Differential does not have slicing then safe to pre-sort the list
      // so elements and subcomponents are together
      Collections.sort(diffList, new ElementNameCompare());
    }

    processElementsIntoTree(edh, i, diff.getDifferential().getElement());

    // now, we sort the siblings throughout the tree
    ElementDefinitionComparer cmp = new ElementDefinitionComparer(true, base.getSnapshot().getElement(), "", 0, name);
    sortElements(edh, cmp, errors);

    // now, we serialise them back to a list
    List<ElementDefinition> newDiff = new ArrayList<>();
    writeElements(edh, newDiff);
    if (errorIfChanges) {
      compareDiffs(original, newDiff, errors);
    }
    diffList.clear();
    diffList.addAll(newDiff);
    
    if (lastCount != diffList.size())
      errors.add("Sort failed: counts differ; at least one of the paths in the differential is illegal");
  }

  private void compareDiffs(List<ElementDefinition> diffList, List<ElementDefinition> newDiff, List<String> errors) {
    if (diffList.size() != newDiff.size()) {
      errors.add("The diff list size changed when sorting - was "+diffList.size()+" is now "+newDiff.size());
    } else {
      for (int i = 0; i < Integer.min(diffList.size(), newDiff.size()); i++) {
        ElementDefinition e = diffList.get(i);
        ElementDefinition n = newDiff.get(i);
        if (!n.getPath().equals(e.getPath())) {
          errors.add("The element "+e.getPath()+" is out of order (and maybe others after it)");
          return;
        }   
      }
    }
  }


  private int processElementsIntoTree(ElementDefinitionHolder edh, int i, List<ElementDefinition> list) {
    String path = edh.getSelf().getPath();
    final String prefix = path + ".";
    while (i < list.size() && list.get(i).getPath().startsWith(prefix)) {
      if (list.get(i).getPath().substring(prefix.length()+1).contains(".")) {
        String newPath = prefix + list.get(i).getPath().substring(prefix.length()).split("\\.")[0];
        ElementDefinition e = new ElementDefinition(newPath);
        ElementDefinitionHolder child = new ElementDefinitionHolder(e, true);
        edh.getChildren().add(child);
        i = processElementsIntoTree(child, i, list);
        
      } else {
        ElementDefinitionHolder child = new ElementDefinitionHolder(list.get(i));
        edh.getChildren().add(child);
        i = processElementsIntoTree(child, i+1, list);
      }
    }
    return i;
  }

  private void sortElements(ElementDefinitionHolder edh, ElementDefinitionComparer cmp, List<String> errors) throws FHIRException {
    if (edh.getChildren().size() == 1)
      // special case - sort needsto allocate base numbers, but there'll be no sort if there's only 1 child. So in that case, we just go ahead and allocated base number directly
      edh.getChildren().get(0).baseIndex = cmp.find(edh.getChildren().get(0).getSelf().getPath(), false);
    else
      Collections.sort(edh.getChildren(), cmp);
    cmp.checkForErrors(errors);

    for (ElementDefinitionHolder child : edh.getChildren()) {
      if (child.getChildren().size() > 0) {
        ElementDefinitionComparer ccmp = getComparer(cmp, child);
        if (ccmp != null) {
          sortElements(child, ccmp, errors);
        }
      }
    }
  }


  public ElementDefinitionComparer getComparer(ElementDefinitionComparer cmp, ElementDefinitionHolder child) throws FHIRException, Error {
    // what we have to check for here is running off the base profile into a data type profile
    ElementDefinition ed = cmp.snapshot.get(child.getBaseIndex());
    ElementDefinitionComparer ccmp;
    if (ed.getType().isEmpty() || isAbstract(ed.getType().get(0).getWorkingCode()) || ed.getType().get(0).getWorkingCode().equals(ed.getPath())) {
      if (ed.hasType() && "Resource".equals(ed.getType().get(0).getWorkingCode()) && (child.getSelf().hasType() && child.getSelf().getType().get(0).hasProfile())) {
        if (child.getSelf().getType().get(0).getProfile().size() > 1) {
          throw new FHIRException(context.formatMessage(I18nConstants.UNHANDLED_SITUATION_RESOURCE_IS_PROFILED_TO_MORE_THAN_ONE_OPTION__CANNOT_SORT_PROFILE));
        }
        StructureDefinition profile = context.fetchResource(StructureDefinition.class, child.getSelf().getType().get(0).getProfile().get(0).getValue());
        while (profile != null && profile.getDerivation() == TypeDerivationRule.CONSTRAINT) {
          profile = context.fetchResource(StructureDefinition.class, profile.getBaseDefinition());          
        }
        if (profile==null) {
          ccmp = null; // this might happen before everything is loaded. And we don't so much care about sot order in this case
        } else {
          ccmp = new ElementDefinitionComparer(true, profile.getSnapshot().getElement(), profile.getType(), child.getSelf().getPath().length(), cmp.name);
        }
      } else {
        ccmp = new ElementDefinitionComparer(true, cmp.snapshot, cmp.base, cmp.prefixLength, cmp.name);
      }
    } else if (ed.getType().get(0).getWorkingCode().equals("Extension") && child.getSelf().getType().size() == 1 && child.getSelf().getType().get(0).hasProfile()) {
      StructureDefinition profile = context.fetchResource(StructureDefinition.class, child.getSelf().getType().get(0).getProfile().get(0).getValue());
      if (profile==null)
        ccmp = null; // this might happen before everything is loaded. And we don't so much care about sot order in this case
      else
      ccmp = new ElementDefinitionComparer(true, profile.getSnapshot().getElement(), resolveType(ed.getType().get(0).getWorkingCode()), child.getSelf().getPath().length(), cmp.name);
    } else if (ed.getType().size() == 1 && !ed.getType().get(0).getWorkingCode().equals("*")) {
      StructureDefinition profile = context.fetchResource(StructureDefinition.class, sdNs(ed.getType().get(0).getWorkingCode()));
      if (profile==null)
        throw new FHIRException(context.formatMessage(I18nConstants.UNABLE_TO_RESOLVE_PROFILE__IN_ELEMENT_, sdNs(ed.getType().get(0).getWorkingCode()), ed.getPath()));
      ccmp = new ElementDefinitionComparer(false, profile.getSnapshot().getElement(), resolveType(ed.getType().get(0).getWorkingCode()), child.getSelf().getPath().length(), cmp.name);
    } else if (child.getSelf().getType().size() == 1) {
      StructureDefinition profile = context.fetchResource(StructureDefinition.class, sdNs(child.getSelf().getType().get(0).getWorkingCode()));
      if (profile==null)
        throw new FHIRException(context.formatMessage(I18nConstants.UNABLE_TO_RESOLVE_PROFILE__IN_ELEMENT_, sdNs(ed.getType().get(0).getWorkingCode()), ed.getPath()));
      ccmp = new ElementDefinitionComparer(false, profile.getSnapshot().getElement(), child.getSelf().getType().get(0).getWorkingCode(), child.getSelf().getPath().length(), cmp.name);
    } else if (ed.getPath().endsWith("[x]") && !child.getSelf().getPath().endsWith("[x]")) {
      String edLastNode = ed.getPath().replaceAll("(.*\\.)*(.*)", "$2");
      String childLastNode = child.getSelf().getPath().replaceAll("(.*\\.)*(.*)", "$2");
      String p = childLastNode.substring(edLastNode.length()-3);
      if (isPrimitive(Utilities.uncapitalize(p)))
        p = Utilities.uncapitalize(p);
      StructureDefinition sd = context.fetchResource(StructureDefinition.class, sdNs(p));
      if (sd == null)
        throw new Error(context.formatMessage(I18nConstants.UNABLE_TO_FIND_PROFILE__AT_, p, ed.getId()));
      ccmp = new ElementDefinitionComparer(false, sd.getSnapshot().getElement(), p, child.getSelf().getPath().length(), cmp.name);
    } else if (child.getSelf().hasType() && child.getSelf().getType().get(0).getWorkingCode().equals("Reference")) {
      for (TypeRefComponent t: child.getSelf().getType()) {
        if (!t.getWorkingCode().equals("Reference")) {
          throw new Error(context.formatMessage(I18nConstants.CANT_HAVE_CHILDREN_ON_AN_ELEMENT_WITH_A_POLYMORPHIC_TYPE__YOU_MUST_SLICE_AND_CONSTRAIN_THE_TYPES_FIRST_SORTELEMENTS_, ed.getPath(), typeCode(ed.getType())));
        }
      }
      StructureDefinition profile = context.fetchResource(StructureDefinition.class, sdNs(ed.getType().get(0).getWorkingCode()));
      ccmp = new ElementDefinitionComparer(false, profile.getSnapshot().getElement(), ed.getType().get(0).getWorkingCode(), child.getSelf().getPath().length(), cmp.name);
    } else if (!child.getSelf().hasType() && ed.getType().get(0).getWorkingCode().equals("Reference")) {
      for (TypeRefComponent t: ed.getType()) {
        if (!t.getWorkingCode().equals("Reference")) {
          throw new Error(context.formatMessage(I18nConstants.NOT_HANDLED_YET_SORTELEMENTS_, ed.getPath(), typeCode(ed.getType())));
        }
      }
      StructureDefinition profile = context.fetchResource(StructureDefinition.class, sdNs(ed.getType().get(0).getWorkingCode()));
      ccmp = new ElementDefinitionComparer(false, profile.getSnapshot().getElement(), ed.getType().get(0).getWorkingCode(), child.getSelf().getPath().length(), cmp.name);
    } else {
      // this is allowed if we only profile the extensions
      StructureDefinition profile = context.fetchResource(StructureDefinition.class, sdNs("Element"));
      if (profile==null)
        throw new FHIRException(context.formatMessage(I18nConstants.UNABLE_TO_RESOLVE_PROFILE__IN_ELEMENT_, sdNs(ed.getType().get(0).getWorkingCode()), ed.getPath()));
      ccmp = new ElementDefinitionComparer(false, profile.getSnapshot().getElement(), "Element", child.getSelf().getPath().length(), cmp.name);
//      throw new Error("Not handled yet (sortElements: "+ed.getPath()+":"+typeCode(ed.getType())+")");
    }
    return ccmp;
  }

  private String resolveType(String code) {
    if (Utilities.isAbsoluteUrl(code)) {
      StructureDefinition sd = context.fetchResource(StructureDefinition.class, code);
      if (sd != null) {
        return sd.getType();
      }
    }
    return code;
  }

  private static String sdNs(String type) {
    return sdNs(type, null);
  }
  
  public static String sdNs(String type, String overrideVersionNs) {
    if (Utilities.isAbsoluteUrl(type))
      return type;
    else if (overrideVersionNs != null)
      return Utilities.pathURL(overrideVersionNs, type);
    else
      return "http://hl7.org/fhir/StructureDefinition/"+type;
  }


  private boolean isAbstract(String code) {
    return code.equals("Element") || code.equals("BackboneElement") || code.equals("Resource") || code.equals("DomainResource");
  }


  private void writeElements(ElementDefinitionHolder edh, List<ElementDefinition> list) {
    if (!edh.isPlaceHolder())
      list.add(edh.getSelf());
    for (ElementDefinitionHolder child : edh.getChildren()) {
      writeElements(child, list);
    }
  }

  /**
   * First compare element by path then by name if same
   */
  private static class ElementNameCompare implements Comparator<ElementDefinition> {

    @Override
    public int compare(ElementDefinition o1, ElementDefinition o2) {
      String path1 = normalizePath(o1);
      String path2 = normalizePath(o2);
      int cmp = path1.compareTo(path2);
      if (cmp == 0) {
        String name1 = o1.hasSliceName() ? o1.getSliceName() : "";
        String name2 = o2.hasSliceName() ? o2.getSliceName() : "";
        cmp = name1.compareTo(name2);
      }
      return cmp;
    }

    private static String normalizePath(ElementDefinition e) {
      if (!e.hasPath()) return "";
      String path = e.getPath();
      // if sorting element names make sure onset[x] appears before onsetAge, onsetDate, etc.
      // so strip off the [x] suffix when comparing the path names.
      if (path.endsWith("[x]")) {
        path = path.substring(0, path.length()-3);
      }
      return path;
    }

  }


  // generate schematrons for the rules in a structure definition
  public void generateSchematrons(OutputStream dest, StructureDefinition structure) throws IOException, DefinitionException {
    if (structure.getDerivation() != TypeDerivationRule.CONSTRAINT)
      throw new DefinitionException(context.formatMessage(I18nConstants.NOT_THE_RIGHT_KIND_OF_STRUCTURE_TO_GENERATE_SCHEMATRONS_FOR));
    if (!structure.hasSnapshot())
      throw new DefinitionException(context.formatMessage(I18nConstants.NEEDS_A_SNAPSHOT));

        StructureDefinition base = context.fetchResource(StructureDefinition.class, structure.getBaseDefinition());

        if (base != null) {
          SchematronWriter sch = new SchematronWriter(dest, SchematronType.PROFILE, base.getName());

          ElementDefinition ed = structure.getSnapshot().getElement().get(0);
          generateForChildren(sch, "f:"+ed.getPath(), ed, structure, base);
          sch.dump();
        }
  }

  // generate a CSV representation of the structure definition
  public void generateCsvs(OutputStream dest, StructureDefinition structure, boolean asXml) throws IOException, DefinitionException, Exception {
    if (!structure.hasSnapshot())
      throw new DefinitionException(context.formatMessage(I18nConstants.NEEDS_A_SNAPSHOT));

    CSVWriter csv = new CSVWriter(dest, structure, asXml);

    for (ElementDefinition child : structure.getSnapshot().getElement()) {
      csv.processElement(child);
    }
    csv.dump();
  }
  
  
  private class Slicer extends ElementDefinitionSlicingComponent {
    String criteria = "";
    String name = "";   
    boolean check;
    public Slicer(boolean cantCheck) {
      super();
      this.check = cantCheck;
    }
  }
  
  private Slicer generateSlicer(ElementDefinition child, ElementDefinitionSlicingComponent slicing, StructureDefinition structure) {
    // given a child in a structure, it's sliced. figure out the slicing xpath
    if (child.getPath().endsWith(".extension")) {
      ElementDefinition ued = getUrlFor(structure, child);
      if ((ued == null || !ued.hasFixed()) && !(child.hasType() && (child.getType().get(0).hasProfile())))
        return new Slicer(false);
      else {
      Slicer s = new Slicer(true);
      String url = (ued == null || !ued.hasFixed()) ? child.getType().get(0).getProfile().get(0).getValue() : ((UriType) ued.getFixed()).asStringValue();
      s.name = " with URL = '"+url+"'";
      s.criteria = "[@url = '"+url+"']";
      return s;
      }
    } else
      return new Slicer(false);
  }

  private void generateForChildren(SchematronWriter sch, String xpath, ElementDefinition ed, StructureDefinition structure, StructureDefinition base) throws IOException {
    //    generateForChild(txt, structure, child);
    List<ElementDefinition> children = getChildList(structure, ed);
    String sliceName = null;
    ElementDefinitionSlicingComponent slicing = null;
    for (ElementDefinition child : children) {
      String name = tail(child.getPath());
      if (child.hasSlicing()) {
        sliceName = name;
        slicing = child.getSlicing();        
      } else if (!name.equals(sliceName))
        slicing = null;

      ElementDefinition based = getByPath(base, child.getPath());
      boolean doMin = (child.getMin() > 0) && (based == null || (child.getMin() != based.getMin()));
      boolean doMax = child.hasMax() && !child.getMax().equals("*") && (based == null || (!child.getMax().equals(based.getMax())));
      Slicer slicer = slicing == null ? new Slicer(true) : generateSlicer(child, slicing, structure);
      if (slicer.check) {
        if (doMin || doMax) {
          Section s = sch.section(xpath);
          Rule r = s.rule(xpath);
          if (doMin) 
            r.assrt("count(f:"+name+slicer.criteria+") >= "+Integer.toString(child.getMin()), name+slicer.name+": minimum cardinality of '"+name+"' is "+Integer.toString(child.getMin()));
          if (doMax) 
            r.assrt("count(f:"+name+slicer.criteria+") <= "+child.getMax(), name+slicer.name+": maximum cardinality of '"+name+"' is "+child.getMax());
        }
      }
    }
    for (ElementDefinitionConstraintComponent inv : ed.getConstraint()) {
      if (inv.hasXpath()) {
        Section s = sch.section(ed.getPath());
        Rule r = s.rule(xpath);
        r.assrt(inv.getXpath(), (inv.hasId() ? inv.getId()+": " : "")+inv.getHuman()+(inv.hasUserData(IS_DERIVED) ? " (inherited)" : ""));
      }
    }
    if (!ed.hasContentReference()) {
      for (ElementDefinition child : children) {
        String name = tail(child.getPath());
        generateForChildren(sch, xpath+"/f:"+name, child, structure, base);
      }
    }
  }




  private ElementDefinition getByPath(StructureDefinition base, String path) {
                for (ElementDefinition ed : base.getSnapshot().getElement()) {
                        if (ed.getPath().equals(path))
                                return ed;
                        if (ed.getPath().endsWith("[x]") && ed.getPath().length() <= path.length()-3 &&  ed.getPath().substring(0, ed.getPath().length()-3).equals(path.substring(0, ed.getPath().length()-3)))
                                return ed;
    }
          return null;
  }


  public void setIds(StructureDefinition sd, boolean checkFirst) throws DefinitionException  {
    if (!checkFirst || !sd.hasDifferential() || hasMissingIds(sd.getDifferential().getElement())) {
      if (!sd.hasDifferential())
        sd.setDifferential(new StructureDefinitionDifferentialComponent());
      generateIds(sd.getDifferential().getElement(), sd.getUrl(), sd.getType());
    }
    if (!checkFirst || !sd.hasSnapshot() || hasMissingIds(sd.getSnapshot().getElement())) {
      if (!sd.hasSnapshot())
        sd.setSnapshot(new StructureDefinitionSnapshotComponent());
      generateIds(sd.getSnapshot().getElement(), sd.getUrl(), sd.getType());
    }
  }


  private boolean hasMissingIds(List<ElementDefinition> list) {
    for (ElementDefinition ed : list) {
      if (!ed.hasId())
        return true;
    }    
    return false;
  }

  public class SliceList {

    private Map<String, String> slices = new HashMap<>();
    
    public void seeElement(ElementDefinition ed) {
      Iterator<Map.Entry<String,String>> iter = slices.entrySet().iterator();
      while (iter.hasNext()) {
        Map.Entry<String,String> entry = iter.next();
        if (entry.getKey().length() > ed.getPath().length() || entry.getKey().equals(ed.getPath()))
          iter.remove();
      }
      
      if (ed.hasSliceName()) 
        slices.put(ed.getPath(), ed.getSliceName());
    }

    public String[] analyse(List<String> paths) {
      String s = paths.get(0);
      String[] res = new String[paths.size()];
      res[0] = null;
      for (int i = 1; i < paths.size(); i++) {
        s = s + "."+paths.get(i);
        if (slices.containsKey(s)) 
          res[i] = slices.get(s);
        else
          res[i] = null;
      }
      return res;
    }

  }

  private void generateIds(List<ElementDefinition> list, String name, String type) throws DefinitionException  {
    if (list.isEmpty())
      return;
    
    Map<String, String> idList = new HashMap<String, String>();
    Map<String, String> replacedIds = new HashMap<String, String>();
    
    SliceList sliceInfo = new SliceList();
    // first pass, update the element ids
    for (ElementDefinition ed : list) {
      List<String> paths = new ArrayList<String>();
      if (!ed.hasPath())
        throw new DefinitionException(context.formatMessage(I18nConstants.NO_PATH_ON_ELEMENT_DEFINITION__IN_, Integer.toString(list.indexOf(ed)), name));
      sliceInfo.seeElement(ed);
      String[] pl = ed.getPath().split("\\.");
      for (int i = paths.size(); i < pl.length; i++) // -1 because the last path is in focus
        paths.add(pl[i]);
      String slices[] = sliceInfo.analyse(paths);
      
      StringBuilder b = new StringBuilder();
      b.append(paths.get(0));
      for (int i = 1; i < paths.size(); i++) {
        b.append(".");
        String s = paths.get(i);
        String p = slices[i];
        b.append(fixChars(s));
        if (p != null) {
          b.append(":");
          b.append(p);
        }
      }
      String bs = b.toString();
      if (ed.hasId()) {
        replacedIds.put(ed.getId(), ed.getPath());
      }
      ed.setId(bs);
      if (idList.containsKey(bs)) {
        if (exception || messages == null) {
          throw new DefinitionException(context.formatMessage(I18nConstants.SAME_ID_ON_MULTIPLE_ELEMENTS__IN_, bs, idList.get(bs), ed.getPath(), name));
        } else
          messages.add(new ValidationMessage(Source.ProfileValidator, ValidationMessage.IssueType.BUSINESSRULE, name+"."+bs, "Duplicate Element id "+bs, ValidationMessage.IssueSeverity.ERROR));
      }
      idList.put(bs, ed.getPath());
      if (ed.hasContentReference() && ed.getContentReference().startsWith("#")) {
        String s = ed.getContentReference();
        if (replacedIds.containsKey(s.substring(1))) {
          ed.setContentReference("http://hl7.org/fhir/StructureDefinition/"+type+"#"+replacedIds.get(s.substring(1)));
        } else {
          ed.setContentReference("http://hl7.org/fhir/StructureDefinition/"+type+s);
        }
      }
    }  
    // second path - fix up any broken path based id references
    
  }


  private Object fixChars(String s) {
    return s.replace("_", "-");
  }


//  private String describeExtension(ElementDefinition ed) {
//    if (!ed.hasType() || !ed.getTypeFirstRep().hasProfile())
//      return "";
//    return "$"+urlTail(ed.getTypeFirstRep().getProfile());
//  }
//

  private static String urlTail(String profile) {
    return profile.contains("/") ? profile.substring(profile.lastIndexOf("/")+1) : profile;
  }


  private String checkName(String name) {
//    if (name.contains("."))
////      throw new Exception("Illegal name "+name+": no '.'");
//    if (name.contains(" "))
//      throw new Exception("Illegal name "+name+": no spaces");
    StringBuilder b = new StringBuilder();
    for (char c : name.toCharArray()) {
      if (!Utilities.existsInList(c, '.', ' ', ':', '"', '\'', '(', ')', '&', '[', ']'))
        b.append(c);
    }
    return b.toString().toLowerCase();
  }


  private int charCount(String path, char t) {
    int res = 0;
    for (char ch : path.toCharArray()) {
      if (ch == t)
        res++;
    }
    return res;
  }

//
//private void generateForChild(TextStreamWriter txt,
//    StructureDefinition structure, ElementDefinition child) {
//  // TODO Auto-generated method stub
//
//}

  private interface ExampleValueAccessor {
    DataType getExampleValue(ElementDefinition ed);
    String getId();
  }

  private class BaseExampleValueAccessor implements ExampleValueAccessor {
    @Override
    public DataType getExampleValue(ElementDefinition ed) {
      if (ed.hasFixed())
        return ed.getFixed();
      if (ed.hasExample())
        return ed.getExample().get(0).getValue();
      else
        return null;
    }

    @Override
    public String getId() {
      return "-genexample";
    }
  }
  
  private class ExtendedExampleValueAccessor implements ExampleValueAccessor {
    private String index;

    public ExtendedExampleValueAccessor(String index) {
      this.index = index;
    }
    @Override
    public DataType getExampleValue(ElementDefinition ed) {
      if (ed.hasFixed())
        return ed.getFixed();
      for (Extension ex : ed.getExtension()) {
       String ndx = ToolingExtensions.readStringExtension(ex, "index");
       DataType value = ToolingExtensions.getExtension(ex, "exValue").getValue();
       if (index.equals(ndx) && value != null)
         return value;
      }
      return null;
    }
    @Override
    public String getId() {
      return "-genexample-"+index;
    }
  }
  
  public List<org.hl7.fhir.r5.elementmodel.Element> generateExamples(StructureDefinition sd, boolean evenWhenNoExamples) throws FHIRException {
    List<org.hl7.fhir.r5.elementmodel.Element> examples = new ArrayList<org.hl7.fhir.r5.elementmodel.Element>();
    if (sd.hasSnapshot()) {
      if (evenWhenNoExamples || hasAnyExampleValues(sd)) 
        examples.add(generateExample(sd, new BaseExampleValueAccessor()));
      for (int i = 1; i <= 50; i++) {
        if (hasAnyExampleValues(sd, Integer.toString(i))) 
          examples.add(generateExample(sd, new ExtendedExampleValueAccessor(Integer.toString(i))));
      }
    }
    return examples;
  }

  private org.hl7.fhir.r5.elementmodel.Element generateExample(StructureDefinition profile, ExampleValueAccessor accessor) throws FHIRException {
    ElementDefinition ed = profile.getSnapshot().getElementFirstRep();
    org.hl7.fhir.r5.elementmodel.Element r = new org.hl7.fhir.r5.elementmodel.Element(ed.getPath(), new Property(context, ed, profile));
    List<ElementDefinition> children = getChildMap(profile, ed);
    for (ElementDefinition child : children) {
      if (child.getPath().endsWith(".id")) {
        org.hl7.fhir.r5.elementmodel.Element id = new org.hl7.fhir.r5.elementmodel.Element("id", new Property(context, child, profile));
        id.setValue(profile.getId()+accessor.getId());
        r.getChildren().add(id);
      } else { 
        org.hl7.fhir.r5.elementmodel.Element e = createExampleElement(profile, child, accessor);
        if (e != null)
          r.getChildren().add(e);
      }
    }
    return r;
  }

  private org.hl7.fhir.r5.elementmodel.Element createExampleElement(StructureDefinition profile, ElementDefinition ed, ExampleValueAccessor accessor) throws FHIRException {
    DataType v = accessor.getExampleValue(ed);
    if (v != null) {
      return new ObjectConverter(context).convert(new Property(context, ed, profile), v);
    } else {
      org.hl7.fhir.r5.elementmodel.Element res = new org.hl7.fhir.r5.elementmodel.Element(tail(ed.getPath()), new Property(context, ed, profile));
      boolean hasValue = false;
      List<ElementDefinition> children = getChildMap(profile, ed);
      for (ElementDefinition child : children) {
        if (!child.hasContentReference()) {
        org.hl7.fhir.r5.elementmodel.Element e = createExampleElement(profile, child, accessor);
        if (e != null) {
          hasValue = true;
          res.getChildren().add(e);
        }
      }
      }
      if (hasValue)
        return res;
      else
        return null;
    }
  }

  private boolean hasAnyExampleValues(StructureDefinition sd, String index) {
    for (ElementDefinition ed : sd.getSnapshot().getElement())
      for (Extension ex : ed.getExtension()) {
        String ndx = ToolingExtensions.readStringExtension(ex, "index");
        Extension exv = ToolingExtensions.getExtension(ex, "exValue");
        if (exv != null) {
          DataType value = exv.getValue();
        if (index.equals(ndx) && value != null)
          return true;
        }
       }
    return false;
  }


  private boolean hasAnyExampleValues(StructureDefinition sd) {
    for (ElementDefinition ed : sd.getSnapshot().getElement())
      if (ed.hasExample())
        return true;
    return false;
  }


  public void populateLogicalSnapshot(StructureDefinition sd) throws FHIRException {
    sd.getSnapshot().getElement().add(sd.getDifferential().getElementFirstRep().copy());
    
    if (sd.hasBaseDefinition()) {
    StructureDefinition base = context.fetchResource(StructureDefinition.class, sd.getBaseDefinition());
    if (base == null)
        throw new FHIRException(context.formatMessage(I18nConstants.UNABLE_TO_FIND_BASE_DEFINITION_FOR_LOGICAL_MODEL__FROM_, sd.getBaseDefinition(), sd.getUrl()));
    copyElements(sd, base.getSnapshot().getElement());
    }
    copyElements(sd, sd.getDifferential().getElement());
  }


  private void copyElements(StructureDefinition sd, List<ElementDefinition> list) {
    for (ElementDefinition ed : list) {
      if (ed.getPath().contains(".")) {
        ElementDefinition n = ed.copy();
        n.setPath(sd.getSnapshot().getElementFirstRep().getPath()+"."+ed.getPath().substring(ed.getPath().indexOf(".")+1));
        sd.getSnapshot().addElement(n);
      }
    }
  }

    
  public void cleanUpDifferential(StructureDefinition sd) {
    if (sd.getDifferential().getElement().size() > 1)
      cleanUpDifferential(sd, 1);
  }
  
  private void cleanUpDifferential(StructureDefinition sd, int start) {
    int level = Utilities.charCount(sd.getDifferential().getElement().get(start).getPath(), '.');
    int c = start;
    int len = sd.getDifferential().getElement().size();
    HashSet<String> paths = new HashSet<String>();
    while (c < len && Utilities.charCount(sd.getDifferential().getElement().get(c).getPath(), '.') == level) {
      ElementDefinition ed = sd.getDifferential().getElement().get(c);
      if (!paths.contains(ed.getPath())) {
        paths.add(ed.getPath());
        int ic = c+1; 
        while (ic < len && Utilities.charCount(sd.getDifferential().getElement().get(ic).getPath(), '.') > level) 
          ic++;
        ElementDefinition slicer = null;
        List<ElementDefinition> slices = new ArrayList<ElementDefinition>();
        slices.add(ed);
        while (ic < len && Utilities.charCount(sd.getDifferential().getElement().get(ic).getPath(), '.') == level) {
          ElementDefinition edi = sd.getDifferential().getElement().get(ic);
          if (ed.getPath().equals(edi.getPath())) {
            if (slicer == null) {
              slicer = new ElementDefinition();
              slicer.setPath(edi.getPath());
              slicer.getSlicing().setRules(SlicingRules.OPEN);
              sd.getDifferential().getElement().add(c, slicer);
              c++;
              ic++;
            }
            slices.add(edi);
          }
          ic++;
          while (ic < len && Utilities.charCount(sd.getDifferential().getElement().get(ic).getPath(), '.') > level) 
            ic++;
        }
        // now we're at the end, we're going to figure out the slicing discriminator
        if (slicer != null)
          determineSlicing(slicer, slices);
      }
      c++;
      if (c < len && Utilities.charCount(sd.getDifferential().getElement().get(c).getPath(), '.') > level) {
        cleanUpDifferential(sd, c);
        c++;
        while (c < len && Utilities.charCount(sd.getDifferential().getElement().get(c).getPath(), '.') > level) 
          c++;
      }
  }
  }


  private void determineSlicing(ElementDefinition slicer, List<ElementDefinition> slices) {
    // first, name them
    int i = 0;
    for (ElementDefinition ed : slices) {
      if (ed.hasUserData("slice-name")) {
        ed.setSliceName(ed.getUserString("slice-name"));
      } else {
        i++;
        ed.setSliceName("slice-"+Integer.toString(i));
      }
    }
    // now, the hard bit, how are they differentiated? 
    // right now, we hard code this...
    if (slicer.getPath().endsWith(".extension") || slicer.getPath().endsWith(".modifierExtension"))
      slicer.getSlicing().addDiscriminator().setType(DiscriminatorType.VALUE).setPath("url");
    else if (slicer.getPath().equals("DiagnosticReport.result"))
      slicer.getSlicing().addDiscriminator().setType(DiscriminatorType.VALUE).setPath("reference.code");
    else if (slicer.getPath().equals("Observation.related"))
      slicer.getSlicing().addDiscriminator().setType(DiscriminatorType.VALUE).setPath("target.reference.code");
    else if (slicer.getPath().equals("Bundle.entry"))
      slicer.getSlicing().addDiscriminator().setType(DiscriminatorType.VALUE).setPath("resource.@profile");
    else  
      throw new Error("No slicing for "+slicer.getPath());
  }

  public class SpanEntry {
    private List<SpanEntry> children = new ArrayList<SpanEntry>();
    private boolean profile;
    private String id;
    private String name;
    private String resType;
    private String cardinality;
    private String description;
    private String profileLink;
    private String resLink;
    private String type;
    
    public String getName() {
      return name;
    }
    public void setName(String name) {
      this.name = name;
    }
    public String getResType() {
      return resType;
    }
    public void setResType(String resType) {
      this.resType = resType;
    }
    public String getCardinality() {
      return cardinality;
    }
    public void setCardinality(String cardinality) {
      this.cardinality = cardinality;
    }
    public String getDescription() {
      return description;
    }
    public void setDescription(String description) {
      this.description = description;
    }
    public String getProfileLink() {
      return profileLink;
    }
    public void setProfileLink(String profileLink) {
      this.profileLink = profileLink;
    }
    public String getResLink() {
      return resLink;
    }
    public void setResLink(String resLink) {
      this.resLink = resLink;
    }
    public String getId() {
      return id;
    }
    public void setId(String id) {
      this.id = id;
    }
    public boolean isProfile() {
      return profile;
    }
    public void setProfile(boolean profile) {
      this.profile = profile;
    }
    public List<SpanEntry> getChildren() {
      return children;
    }
    public String getType() {
      return type;
    }
    public void setType(String type) {
      this.type = type;
    }
    
  }

  public XhtmlNode generateSpanningTable(StructureDefinition profile, String imageFolder, boolean onlyConstraints, String constraintPrefix, Set<String> outputTracker) throws IOException, FHIRException {
    HierarchicalTableGenerator gen = new HierarchicalTableGenerator(imageFolder, false, true);
    gen.setTranslator(getTranslator());
    TableModel model = initSpanningTable(gen, "", false, profile.getId());
    Set<String> processed = new HashSet<String>();
    SpanEntry span = buildSpanningTable("(focus)", "", profile, processed, onlyConstraints, constraintPrefix);
    
    genSpanEntry(gen, model.getRows(), span);
    return gen.generate(model, "", 0, outputTracker);
  }

  private SpanEntry buildSpanningTable(String name, String cardinality, StructureDefinition profile, Set<String> processed, boolean onlyConstraints, String constraintPrefix) throws IOException {
    SpanEntry res = buildSpanEntryFromProfile(name, cardinality, profile);
    boolean wantProcess = !processed.contains(profile.getUrl());
    processed.add(profile.getUrl());
    if (wantProcess && profile.getDerivation() == TypeDerivationRule.CONSTRAINT) {
      for (ElementDefinition ed : profile.getSnapshot().getElement()) {
        if (!"0".equals(ed.getMax()) && ed.getType().size() > 0) {
          String card = getCardinality(ed, profile.getSnapshot().getElement());
          if (!card.endsWith(".0")) {
            List<String> refProfiles = listReferenceProfiles(ed);
            if (refProfiles.size() > 0) {
              String uri = refProfiles.get(0);
              if (uri != null) {
                StructureDefinition sd = context.fetchResource(StructureDefinition.class, uri);
                if (sd != null && (!onlyConstraints || (sd.getDerivation() == TypeDerivationRule.CONSTRAINT && (constraintPrefix == null || sd.getUrl().startsWith(constraintPrefix))))) {
                  res.getChildren().add(buildSpanningTable(nameForElement(ed), card, sd, processed, onlyConstraints, constraintPrefix));
                }
              }
            }
          }
        } 
      }
    }
    return res;
  }


  private String getCardinality(ElementDefinition ed, List<ElementDefinition> list) {
    int min = ed.getMin();
    int max = !ed.hasMax() || ed.getMax().equals("*") ? Integer.MAX_VALUE : Integer.parseInt(ed.getMax());
    ElementDefinition ned = ed;
    while (ned != null && ned.getPath().contains(".")) {
      ned = findParent(ned, list);
      if (ned != null) { // todo: this can happen if we've walked into a resoruce. Not sure what to about that?
        if ("0".equals(ned.getMax()))
          max = 0;
        else if (!ned.getMax().equals("1") && !ned.hasSlicing())
          max = Integer.MAX_VALUE;
        if (ned.getMin() == 0) {
          min = 0;
        }
      }
    }
    return Integer.toString(min)+".."+(max == Integer.MAX_VALUE ? "*" : Integer.toString(max));
  }


  private ElementDefinition findParent(ElementDefinition ed, List<ElementDefinition> list) {
    int i = list.indexOf(ed)-1;
    while (i >= 0 && !ed.getPath().startsWith(list.get(i).getPath()+"."))
      i--;
    if (i == -1)
      return null;
    else
      return list.get(i);
  }


  private List<String> listReferenceProfiles(ElementDefinition ed) {
    List<String> res = new ArrayList<String>();
    for (TypeRefComponent tr : ed.getType()) {
      // code is null if we're dealing with "value" and profile is null if we just have Reference()
      if (tr.hasTarget() && tr.hasTargetProfile())
        for (UriType u : tr.getTargetProfile())
          res.add(u.getValue());
    }
    return res;
  }


  private String nameForElement(ElementDefinition ed) {
    return ed.getPath().substring(ed.getPath().indexOf(".")+1);
  }


  private SpanEntry buildSpanEntryFromProfile(String name, String cardinality, StructureDefinition profile) throws IOException {
    SpanEntry res = new SpanEntry();
    res.setName(name);
    res.setCardinality(cardinality);
    res.setProfileLink(profile.getUserString("path"));
    res.setResType(profile.getType());
    StructureDefinition base = context.fetchResource(StructureDefinition.class, res.getResType());
    if (base != null)
      res.setResLink(base.getUserString("path"));
    res.setId(profile.getId());
    res.setProfile(profile.getDerivation() == TypeDerivationRule.CONSTRAINT);
    StringBuilder b = new StringBuilder();
    b.append(res.getResType());
    boolean first = true;
    boolean open = false;
    if (profile.getDerivation() == TypeDerivationRule.CONSTRAINT) {
      res.setDescription(profile.getName());
      for (ElementDefinition ed : profile.getSnapshot().getElement()) {
        if (isKeyProperty(ed.getBase().getPath()) && ed.hasFixed()) {
          if (first) {
            open = true;
            first = false;
            b.append("[");
          } else {
            b.append(", ");
          }
          b.append(tail(ed.getBase().getPath()));
          b.append("=");
          b.append(summarize(ed.getFixed()));
        }
      }
      if (open)
        b.append("]");
    } else
      res.setDescription("Base FHIR "+profile.getName());
    res.setType(b.toString());
    return res ;
  }


  private String summarize(DataType value) throws IOException {
    if (value instanceof Coding)
      return summarizeCoding((Coding) value);
    else if (value instanceof CodeableConcept)
      return summarizeCodeableConcept((CodeableConcept) value);
    else
      return buildJson(value);
  }


  private String summarizeCoding(Coding value) {
    String uri = value.getSystem();
    String system = TerminologyRenderer.describeSystem(uri);
    if (Utilities.isURL(system)) {
      if (system.equals("http://cap.org/protocols"))
        system = "CAP Code";
    }
    return system+" "+value.getCode();
  }


  private String summarizeCodeableConcept(CodeableConcept value) {
    if (value.hasCoding())
      return summarizeCoding(value.getCodingFirstRep());
    else
      return value.getText();
  }


  private boolean isKeyProperty(String path) {
    return Utilities.existsInList(path, "Observation.code");
  }


  public TableModel initSpanningTable(HierarchicalTableGenerator gen, String prefix, boolean isLogical, String id) {
    TableModel model = gen.new TableModel(id, true);
    
    model.setDocoImg(prefix+"help16.png");
    model.setDocoRef(Utilities.pathURL(prefix, "formats.html#table")); // todo: change to graph definition
    model.getTitles().add(gen.new Title(null, model.getDocoRef(), "Property", "A profiled resource", null, 0));
    model.getTitles().add(gen.new Title(null, model.getDocoRef(), "Card.", "Minimum and Maximum # of times the the element can appear in the instance", null, 0));
    model.getTitles().add(gen.new Title(null, model.getDocoRef(), "Content", "What goes here", null, 0));
    model.getTitles().add(gen.new Title(null, model.getDocoRef(), "Description", "Description of the profile", null, 0));
    return model;
  }

  private void genSpanEntry(HierarchicalTableGenerator gen, List<Row> rows, SpanEntry span) throws IOException {
    Row row = gen.new Row();
    rows.add(row);
    row.setAnchor(span.getId());
    //row.setColor(..?);
    if (span.isProfile()) {
      row.setIcon("icon_profile.png", HierarchicalTableGenerator.TEXT_ICON_PROFILE);
    } else {
      row.setIcon("icon_resource.png", HierarchicalTableGenerator.TEXT_ICON_RESOURCE);
    }
    
    row.getCells().add(gen.new Cell(null, null, span.getName(), null, null));
    row.getCells().add(gen.new Cell(null, null, span.getCardinality(), null, null));
    row.getCells().add(gen.new Cell(null, span.getProfileLink(), span.getType(), null, null));
    row.getCells().add(gen.new Cell(null, null, span.getDescription(), null, null));

    for (SpanEntry child : span.getChildren()) {
      genSpanEntry(gen, row.getSubRows(), child);
    }
  }


  public static ElementDefinitionSlicingDiscriminatorComponent interpretR2Discriminator(String discriminator, boolean isExists) {
    if (discriminator.endsWith("@pattern"))
      return makeDiscriminator(DiscriminatorType.PATTERN, discriminator.length() == 8 ? "" : discriminator.substring(0,discriminator.length()-9)); 
    if (discriminator.endsWith("@profile"))
      return makeDiscriminator(DiscriminatorType.PROFILE, discriminator.length() == 8 ? "" : discriminator.substring(0,discriminator.length()-9)); 
    if (discriminator.endsWith("@type")) 
      return makeDiscriminator(DiscriminatorType.TYPE, discriminator.length() == 5 ? "" : discriminator.substring(0,discriminator.length()-6));
    if (discriminator.endsWith("@exists"))
      return makeDiscriminator(DiscriminatorType.EXISTS, discriminator.length() == 7 ? "" : discriminator.substring(0,discriminator.length()-8)); 
    if (isExists)
      return makeDiscriminator(DiscriminatorType.EXISTS, discriminator); 
    return new ElementDefinitionSlicingDiscriminatorComponent().setType(DiscriminatorType.VALUE).setPath(discriminator);
  }


  private static ElementDefinitionSlicingDiscriminatorComponent makeDiscriminator(DiscriminatorType dType, String str) {
    return new ElementDefinitionSlicingDiscriminatorComponent().setType(dType).setPath(Utilities.noString(str)? "$this" : str);
  }


  public static String buildR2Discriminator(ElementDefinitionSlicingDiscriminatorComponent t) throws FHIRException {
    switch (t.getType()) {
    case PROFILE: return t.getPath()+"/@profile";
    case PATTERN: return t.getPath()+"/@pattern";
    case TYPE: return t.getPath()+"/@type";
    case VALUE: return t.getPath();
    case EXISTS: return t.getPath(); // determination of value vs. exists is based on whether there's only 2 slices - one with minOccurs=1 and other with maxOccur=0
    default: throw new FHIRException("Unable to represent "+t.getType().toCode()+":"+t.getPath()+" in R2");    
    }
  }


  public static StructureDefinition makeExtensionForVersionedURL(IWorkerContext context, String url) {
    String epath = url.substring(54);
    if (!epath.contains("."))
      return null;
    String type = epath.substring(0, epath.indexOf("."));
    StructureDefinition sd = context.fetchTypeDefinition(type);
    if (sd == null)
      return null;
    ElementDefinition ed = null;
    for (ElementDefinition t : sd.getSnapshot().getElement()) {
      if (t.getPath().equals(epath)) {
        ed = t;
        break;
      }
    }
    if (ed == null)
      return null;
    if ("Element".equals(ed.typeSummary()) || "BackboneElement".equals(ed.typeSummary())) {
      return null;
    } else {
      StructureDefinition template = context.fetchResource(StructureDefinition.class, "http://fhir-registry.smarthealthit.org/StructureDefinition/capabilities");
      StructureDefinition ext = template.copy();
      ext.setUrl(url);
      ext.setId("extension-"+epath);
      ext.setName("Extension-"+epath);
      ext.setTitle("Extension for r4 "+epath);
      ext.setStatus(sd.getStatus());
      ext.setDate(sd.getDate());
      ext.getContact().clear();
      ext.getContact().addAll(sd.getContact());
      ext.setFhirVersion(sd.getFhirVersion());
      ext.setDescription(ed.getDefinition());
      ext.getContext().clear();
      ext.addContext().setType(ExtensionContextType.ELEMENT).setExpression(epath.substring(0, epath.lastIndexOf(".")));
      ext.getDifferential().getElement().clear();
      ext.getSnapshot().getElement().get(3).setFixed(new UriType(url));
      ext.getSnapshot().getElement().set(4, ed.copy());
      ext.getSnapshot().getElement().get(4).setPath("Extension.value"+Utilities.capitalize(ed.typeSummary()));
      return ext;      
    }

  }


  public boolean isThrowException() {
    return exception;
  }


  public void setThrowException(boolean exception) {
    this.exception = exception;
  }


  public ValidationOptions getTerminologyServiceOptions() {
    return terminologyServiceOptions;
  }


  public void setTerminologyServiceOptions(ValidationOptions terminologyServiceOptions) {
    this.terminologyServiceOptions = terminologyServiceOptions;
  }


  public boolean isNewSlicingProcessing() {
    return newSlicingProcessing;
  }


  public void setNewSlicingProcessing(boolean newSlicingProcessing) {
    this.newSlicingProcessing = newSlicingProcessing;
  }


  public boolean isDebug() {
    return debug;
  }


  public void setDebug(boolean debug) {
    this.debug = debug;
  }


  public String getDefWebRoot() {
    return defWebRoot;
  }


  public void setDefWebRoot(String defWebRoot) {
    this.defWebRoot = defWebRoot;
    if (!this.defWebRoot.endsWith("/"))
      this.defWebRoot = this.defWebRoot + '/';
  }


  public static StructureDefinition makeBaseDefinition(FHIRVersion fhirVersion) {
    StructureDefinition base = new StructureDefinition();
    base.setId("Base");
    base.setUrl("http://hl7.org/fhir/StructureDefinition/Base");
    base.setVersion(fhirVersion.toCode());
    base.setName("Base"); 
    base.setStatus(PublicationStatus.ACTIVE);
    base.setDate(new Date());
    base.setFhirVersion(fhirVersion);
    base.setKind(StructureDefinitionKind.COMPLEXTYPE); 
    base.setAbstract(true); 
    base.setType("Base");
    ElementDefinition e = base.getSnapshot().getElementFirstRep();
    e.setId("Base");
    e.setPath("Base"); 
    e.setMin(0); 
    e.setMax("*"); 
    e.getBase().setPath("Base");
    e.getBase().setMin(0); 
    e.getBase().setMax("*"); 
    e.setIsModifier(false); 
    e = base.getDifferential().getElementFirstRep();
    e.setId("Base");
    e.setPath("Base"); 
    e.setMin(0); 
    e.setMax("*"); 
    return base;
  }

  public XVerExtensionManager getXver() {
    return xver;
  }

  public ProfileUtilities setXver(XVerExtensionManager xver) {
    this.xver = xver;
    return this;
  }


  public List<ElementChoiceGroup> readChoices(ElementDefinition ed, List<ElementDefinition> children) {
    List<ElementChoiceGroup> result = new ArrayList<>();
    for (ElementDefinitionConstraintComponent c : ed.getConstraint()) {
      ElementChoiceGroup grp = processConstraint(children, c);
      if (grp != null) {
        result.add(grp);
      }
    }
    return result;
  }

  private ElementChoiceGroup processConstraint(List<ElementDefinition> children, ElementDefinitionConstraintComponent c) {
    if (!c.hasExpression()) {
      return null;
    }
    ExpressionNode expr = null;
    try {
      expr = fpe.parse(c.getExpression());
    } catch (Exception e) {
      return null;
    }
    if (expr.getKind() != Kind.Group || expr.getOpNext() == null || !(expr.getOperation() == Operation.Equals || expr.getOperation() == Operation.LessOrEqual)) {
      return null;      
    }
    ExpressionNode n1 = expr.getGroup();
    ExpressionNode n2 = expr.getOpNext();
    if (n2.getKind() != Kind.Constant || n2.getInner() != null || n2.getOpNext() != null || !"1".equals(n2.getConstant().primitiveValue())) {
      return null;
    }
    ElementChoiceGroup grp = new ElementChoiceGroup(c.getKey(), expr.getOperation() == Operation.Equals);
    while (n1 != null) {
      if (n1.getKind() != Kind.Name || n1.getInner() != null) {
        return null;
      }
      grp.elements.add(n1.getName());
      if (n1.getOperation() == null || n1.getOperation() == Operation.Union) {
        n1 = n1.getOpNext();
      } else {
        return null;
      }
    }
    int total = 0;
    for (String n : grp.elements) {
      boolean found = false;
      for (ElementDefinition child : children) {
        String name = tail(child.getPath());
        if (n.equals(name)) {
          found = true;
          if (!"0".equals(child.getMax())) {
            total++;
          }
        }
      }
      if (!found) {
        return null;
      }
    }
    if (total <= 1) {
      return null;
    }
    return grp;
  }

  public static boolean allTypesMustSupport(ElementDefinition e) {
    boolean all = true;
    boolean any = false;
    for (TypeRefComponent tr : e.getType()) {
      all = all && isMustSupport(tr);
      any = any || isMustSupport(tr);
    }
    return !all && !any;
  }
  
  public static boolean allProfilesMustSupport(List<CanonicalType> profiles) {
    boolean all = true;
    boolean any = false;
    for (CanonicalType u : profiles) {
      all = all && isMustSupport(u);
      any = any || isMustSupport(u);
    }
    return !all && !any;
  }
  public static boolean isMustSupportDirect(TypeRefComponent tr) {
    return ("true".equals(ToolingExtensions.readStringExtension(tr, ToolingExtensions.EXT_MUST_SUPPORT)));
  }

  public static boolean isMustSupport(TypeRefComponent tr) {
    if ("true".equals(ToolingExtensions.readStringExtension(tr, ToolingExtensions.EXT_MUST_SUPPORT))) {
      return true;
    }
    if (isMustSupport(tr.getProfile())) {
      return true;
    }
    return isMustSupport(tr.getTargetProfile());
  }

  public static boolean isMustSupport(List<CanonicalType> profiles) {
    for (CanonicalType ct : profiles) {
      if (isMustSupport(ct)) {
        return true;
      }
    }
    return false;
  }


  public static boolean isMustSupport(CanonicalType profile) {
    return "true".equals(ToolingExtensions.readStringExtension(profile, ToolingExtensions.EXT_MUST_SUPPORT));
  }

  public ElementDefinitionResolution resolveContentRef(StructureDefinition structure, ElementDefinition element) {
    return getElementById(structure, structure.getSnapshot().getElement(), element.getContentReference());
  }

  public Set<String> getMasterSourceFileNames() {
    return masterSourceFileNames;
  }

  public void setMasterSourceFileNames(Set<String> masterSourceFileNames) {
    this.masterSourceFileNames = masterSourceFileNames;
  }

  
}