net.sf.saxon.expr

Class SingletonComparison

java.lang.Object

net.sf.saxon.expr.ComputedExpression

net.sf.saxon.expr.BinaryExpression

net.sf.saxon.expr.SingletonComparison

All Implemented Interfaces:

Serializable, SourceLocator, Container, Expression, InstructionInfoProvider

public class SingletonComparison
extends BinaryExpression

Class to handle comparisons of singletons. Unlike ValueComparison, this class converts untyped atomic values to the type of the other argument, and returns false (rather than ()) if either operand is ().

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.BinaryExpression

operand0, operand1, operator

Fields inherited from class net.sf.saxon.expr.ComputedExpression

locationId, staticProperties

Fields inherited from interface net.sf.saxon.expr.Expression

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

Constructors

Constructor and Description
SingletonComparison(Expression p1, int operator, Expression p2)

Method Summary

Modifier and Type	Method and Description
int	computeCardinality() Determine the static cardinality.
protected String	displayOperator()
boolean	effectiveBooleanValue(XPathContext context) Evaluate the expression in a boolean context
Item	evaluateItem(XPathContext context) Evaluate the expression in a given context
ItemType	getItemType(TypeHierarchy th) Determine the data type of the expression
void	setComparator(Comparator comp, XPathContext context)

Methods inherited from class net.sf.saxon.expr.BinaryExpression

computeSpecialProperties, display, equals, getOperands, getOperator, hashCode, isAssociative, isCommutative, isInverse, iterateSubExpressions, optimize, promote, simplify, typeCheck

Methods inherited from class net.sf.saxon.expr.ComputedExpression

adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, dynamicError, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, suppressValidation, typeError, typeError

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SingletonComparison

public SingletonComparison(Expression p1,
                           int operator,
                           Expression p2)

Method Detail

setComparator

public void setComparator(Comparator comp,
                          XPathContext context)

computeCardinality

public int computeCardinality()

Determine the static cardinality. Returns [1..1]

Overrides:

computeCardinality in class BinaryExpression

getItemType

public ItemType getItemType(TypeHierarchy th)

Determine the data type of the expression

Parameters:

th -

Returns:

Type.BOOLEAN

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Evaluate the expression in a given context

Specified by:

evaluateItem in interface Expression

Overrides:

evaluateItem in class ComputedExpression

Parameters:

context - the given context for evaluation

Returns:

a BooleanValue representing the result of the numeric comparison of the two operands

Throws:

XPathException - if any dynamic error occurs evaluating the expression

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)
                              throws XPathException

Evaluate the expression in a boolean context

Specified by:

effectiveBooleanValue in interface Expression

Overrides:

effectiveBooleanValue in class ComputedExpression

Parameters:

context - the given context for evaluation

Returns:

a boolean representing the result of the numeric comparison of the two operands

Throws:

XPathException - if any dynamic error occurs evaluating the expression

displayOperator

protected String displayOperator()

Overrides:

displayOperator in class BinaryExpression