Package org.apache.jena.sparql.expr

Class ExprAggregator

java.lang.Object

org.apache.jena.sparql.expr.ExprNode

org.apache.jena.sparql.expr.ExprAggregator

All Implemented Interfaces:

Expr

public class ExprAggregator
extends ExprNode

Group aggregation functions calculated a value during grouping and placed in the output binding. This class is relationship of an aggregation expression and that variable. Evaluation returns the variable's bound value.

Field Summary

Fields inherited from interface org.apache.jena.sparql.expr.Expr

CMP_EQUAL, CMP_GREATER, CMP_INDETERMINATE, CMP_LESS, CMP_UNEQUAL, NONE

Constructor Summary

Constructors

Constructor	Description
ExprAggregator(Var v, Aggregator agg)

Method Summary

Modifier and Type	Method	Description
Expr	apply(ExprTransform transform)
ExprAggregator	applyNodeTransform(NodeTransform transform)	Rewrite, applying a node->node transformation
java.lang.String	asSparqlExpr(SerializationContext sCxt)
Var	asVar()	Convert to a Var variable.
Expr	copy(Var v)
ExprAggregator	copySubstitute(Binding binding)	Deep copy with substitution
boolean	equals(Expr other, boolean bySyntax)	General equality operation - consider this to be 'protected'
NodeValue	eval(Binding binding, FunctionEnv env)	Evaluate this expression against the binding
Aggregator	getAggregator()
ExprVar	getAggVar()
ExprVar	getExprVar()	Variable (or null)
Var	getVar()
int	hashCode()	Expr are used in both syntax and algebra.
void	setVar(Var v)
java.lang.String	toString()
void	visit(ExprVisitor visitor)

Methods inherited from class org.apache.jena.sparql.expr.ExprNode

deepCopy, equals, equalsBySyntax, getConstant, getExpr, getFunction, getGraphPattern, getVarName, getVarsMentioned, isConstant, isExpr, isFunction, isGraphPattern, isSatisfied, isVariable

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ExprAggregator

public ExprAggregator(Var v,
                      Aggregator agg)

Method Detail

getVar

public Var getVar()

setVar

public void setVar(Var v)

getAggregator

public Aggregator getAggregator()

hashCode

public int hashCode()

Description copied from interface: Expr

Expr are used in both syntax and algebra. There is no syntax to algebra translation step because the parser uses operator precedence to build the right evaluation structure directly.

The exceptions to this are the NOT EXISTS and EXISTS expressions which involve a query pattern. As a result there are different ways in syntax to produce the same algebra form.

Two Expr are considered equal if they are equal as algebra expressions. hashCode and equals must implement that.

There is also equalsBySyntax. Because two different syntax forms can yield the same algebra, but two different algebra forms must be different syntax, equalsBySyntax implies equals (by alegbra).

Hence, different hashCode => not equalsBySyntax.

Specified by:

hashCode in interface Expr

Specified by:

hashCode in class ExprNode

equals

public boolean equals(Expr other,
                      boolean bySyntax)

Description copied from interface: Expr

General equality operation - consider this to be 'protected'

Specified by:

equals in interface Expr

Specified by:

equals in class ExprNode

getExprVar

public ExprVar getExprVar()

Description copied from interface: Expr

Variable (or null)

Specified by:

getExprVar in interface Expr

Overrides:

getExprVar in class ExprNode

asVar

public Var asVar()

Description copied from interface: Expr

Convert to a Var variable.

Specified by:

asVar in interface Expr

Overrides:

asVar in class ExprNode

getAggVar

public ExprVar getAggVar()

asSparqlExpr

public java.lang.String asSparqlExpr(SerializationContext sCxt)

copySubstitute

public ExprAggregator copySubstitute(Binding binding)

Description copied from interface: Expr

Deep copy with substitution

Specified by:

copySubstitute in interface Expr

Specified by:

copySubstitute in class ExprNode

applyNodeTransform

public ExprAggregator applyNodeTransform(NodeTransform transform)

Description copied from interface: Expr

Rewrite, applying a node->node transformation

Specified by:

applyNodeTransform in interface Expr

Specified by:

applyNodeTransform in class ExprNode

toString

public java.lang.String toString()

Overrides:

toString in class ExprNode

copy

public Expr copy(Var v)

eval

public NodeValue eval(Binding binding,
                      FunctionEnv env)

Description copied from interface: Expr

Evaluate this expression against the binding

Specified by:

eval in interface Expr

Specified by:

eval in class ExprNode

apply

public Expr apply(ExprTransform transform)

visit

public void visit(ExprVisitor visitor)