public class Existence extends SystemFunction implements Negatable
?????? | ????? |
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static int |
EMPTY |
static int |
EXISTS |
operation
argument
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
?????? |
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Existence() |
?????? | ????? |
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void |
checkArguments(ExpressionVisitor visitor)
Static analysis: prevent sorting of the argument
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boolean |
effectiveBooleanValue(XPathContext c)
Evaluate the function in a boolean context
|
Item |
evaluateItem(XPathContext c)
Evaluate in a general context
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boolean |
isNegatable(ExpressionVisitor visitor)
Check whether this specific instance of the expression is negatable
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Expression |
negate()
Return the negation of the expression
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Expression |
optimize(ExpressionVisitor visitor,
ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
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addContextDocumentArgument, addDocToPathMap, computeCardinality, computeSpecialProperties, copy, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, makeSystemFunction, setDetails, useContextItemAsDefault
addExternalFunctionCallToPathMap, checkArgumentCount, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString, typeCheck
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, dynamicError, evaluateAsString, evaluatePendingUpdates, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterate, iterateEvents, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError
public static final int EXISTS
public static final int EMPTY
public void checkArguments(ExpressionVisitor visitor) throws XPathException
checkArguments
??? SystemFunction
visitor
- the expression visitorXPathException
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.
optimize
??? SystemFunction
visitor
- an expression visitorcontextItemType
- the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
Type.ITEM_TYPE
XPathException
- if an error is discovered during this phase
(typically a type error)public boolean isNegatable(ExpressionVisitor visitor)
isNegatable
???? Negatable
public Expression negate()
public boolean effectiveBooleanValue(XPathContext c) throws XPathException
effectiveBooleanValue
??? Expression
c
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expressionpublic Item evaluateItem(XPathContext c) throws XPathException
evaluateItem
???? EvaluableItem
evaluateItem
??? Expression
c
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expression