Package net.sf.saxon.functions
Class Existence
java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.FunctionCall
net.sf.saxon.functions.SystemFunction
net.sf.saxon.functions.Existence
- All Implemented Interfaces:
Serializable
,SourceLocator
,LocationProvider
,SaxonLocator
,EvaluableItem
,Negatable
,SequenceIterable
,InstructionInfo
,Locator
Implement the exists() and empty() functions
- See Also:
-
Field Summary
FieldsFields inherited from class net.sf.saxon.functions.SystemFunction
operation
Fields inherited from class net.sf.saxon.expr.FunctionCall
argument
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
checkArguments
(ExpressionVisitor visitor) Static analysis: prevent sorting of the argumentboolean
Evaluate the function in a boolean contextEvaluate in a general contextboolean
isNegatable
(ExpressionVisitor visitor) Check whether this specific instance of the expression is negatablenegate()
Return the negation of the expressionoptimize
(ExpressionVisitor visitor, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, addDocToPathMap, computeCardinality, computeSpecialProperties, copy, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, makeSystemFunction, setDetails, useContextItemAsDefault
Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, checkArgumentCount, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString, typeCheck
Methods inherited from class net.sf.saxon.expr.Expression
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
-
Field Details
-
EXISTS
public static final int EXISTS- See Also:
-
EMPTY
public static final int EMPTY- See Also:
-
-
Constructor Details
-
Existence
public Existence()
-
-
Method Details
-
checkArguments
Static analysis: prevent sorting of the argument- Overrides:
checkArguments
in classSystemFunction
- Parameters:
visitor
- the expression visitor- Throws:
XPathException
-
optimize
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException Perform optimisation of an expression and its subexpressions.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.
- Overrides:
optimize
in classSystemFunction
- Parameters:
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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten if appropriate to optimize execution
- Throws:
XPathException
- if an error is discovered during this phase (typically a type error)
-
isNegatable
Check whether this specific instance of the expression is negatable- Specified by:
isNegatable
in interfaceNegatable
- Returns:
- true if it is
-
negate
Return the negation of the expression -
effectiveBooleanValue
Evaluate the function in a boolean context- Overrides:
effectiveBooleanValue
in classExpression
- 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
-
evaluateItem
Evaluate in a general context- Specified by:
evaluateItem
in interfaceEvaluableItem
- Overrides:
evaluateItem
in classExpression
- 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
-