Package net.sf.saxon.functions
Class Existence
- java.lang.Object
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- net.sf.saxon.expr.ComputedExpression
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- net.sf.saxon.expr.FunctionCall
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- net.sf.saxon.functions.SystemFunction
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- net.sf.saxon.functions.Existence
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,Container
,Expression
,InstructionInfoProvider
public class Existence extends SystemFunction
Implement the exists() and empty() functions- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description static int
EMPTY
static int
EXISTS
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Fields inherited from class net.sf.saxon.functions.SystemFunction
operation
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Fields inherited from class net.sf.saxon.expr.FunctionCall
argument
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Fields inherited from class net.sf.saxon.expr.ComputedExpression
locationId, staticProperties
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Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
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Constructor Summary
Constructors Constructor Description Existence()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
checkArguments(StaticContext env)
Static analysis: prevent sorting of the argumentboolean
effectiveBooleanValue(XPathContext c)
Evaluate the function in a boolean contextItem
evaluateItem(XPathContext c)
Evaluate in a general context-
Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, computeCardinality, computeSpecialProperties, display, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, main, makeSystemFunction, setDetails, useContextItemAsDefault
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Methods inherited from class net.sf.saxon.expr.FunctionCall
checkArgumentCount, getArguments, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, optimize, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionNameCode, simplify, simplifyArguments, typeCheck
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Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, 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, setParentExpression, suppressValidation, typeError
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Field Detail
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EXISTS
public static final int EXISTS
- See Also:
- Constant Field Values
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EMPTY
public static final int EMPTY
- See Also:
- Constant Field Values
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Method Detail
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checkArguments
public void checkArguments(StaticContext env) throws XPathException
Static analysis: prevent sorting of the argument- Overrides:
checkArguments
in classSystemFunction
- Throws:
XPathException
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effectiveBooleanValue
public boolean effectiveBooleanValue(XPathContext c) throws XPathException
Evaluate the function in a boolean context- Specified by:
effectiveBooleanValue
in interfaceExpression
- Overrides:
effectiveBooleanValue
in classComputedExpression
- Parameters:
c
- The context in which the expression is to be evaluated- Returns:
- the effective boolean value
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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evaluateItem
public Item evaluateItem(XPathContext c) throws XPathException
Evaluate in a general context- Specified by:
evaluateItem
in interfaceExpression
- Overrides:
evaluateItem
in classComputedExpression
- Parameters:
c
- The context in which the expression is to be evaluated- Returns:
- the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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