Package org.apache.jena.sparql.expr

Class ExprFunction0

java.lang.Object

org.apache.jena.sparql.expr.ExprNode

org.apache.jena.sparql.expr.ExprFunction

org.apache.jena.sparql.expr.ExprFunction0

All Implemented Interfaces:

Expr

Direct Known Subclasses:

E_Random, E_StrUUID, E_UUID, E_Version, ExprSystem

public abstract class ExprFunction0
extends ExprFunction

An expression that is constant (does not depend on evaluating a sub expression).

Field Summary

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

CMP_EQUAL, CMP_GREATER, CMP_INDETERMINATE, CMP_LESS, CMP_UNEQUAL, NONE

Method Summary

Modifier and Type	Method	Description
Expr	apply(ExprTransform transform)
Expr	applyNodeTransform(NodeTransform transform)	Rewrite, applying a node->node transformation
abstract Expr	copy()
Expr	copySubstitute(Binding binding)	Deep copy with substitution
NodeValue	eval(Binding binding, FunctionEnv env)	Evaluate this expression against the binding
abstract NodeValue	eval(FunctionEnv env)
Expr	getArg(int i)
int	hashCode()	Expr are used in both syntax and algebra.
int	numArgs()
void	visit(ExprVisitor visitor)

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

equals, getArgs, getFunction, getFunctionIRI, getFunctionName, getFunctionPrintName, getFunctionSymbol, getOpName, isFunction

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

asVar, deepCopy, equals, equalsBySyntax, getConstant, getExpr, getExprVar, getGraphPattern, getVarName, getVarsMentioned, isConstant, isExpr, isGraphPattern, isSatisfied, isVariable, toString

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Method Detail

getArg

public Expr getArg(int i)

Specified by:

getArg in class ExprFunction

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

Overrides:

hashCode in class ExprFunction

numArgs

public int numArgs()

Specified by:

numArgs in class ExprFunction

eval

public final 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

eval

public abstract NodeValue eval(FunctionEnv env)

applyNodeTransform

public final Expr 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

copy

public abstract Expr copy()

copySubstitute

public final Expr copySubstitute(Binding binding)

Description copied from interface: Expr

Deep copy with substitution

Specified by:

copySubstitute in interface Expr

Specified by:

copySubstitute in class ExprNode

visit

public void visit(ExprVisitor visitor)

apply

public Expr apply(ExprTransform transform)