Package net.sf.saxon.functions
Class KeyFn
- 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.KeyFn
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,Container
,Expression
,XSLTFunction
,InstructionInfoProvider
public class KeyFn extends SystemFunction implements XSLTFunction
- See Also:
- Serialized Form
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Field Summary
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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 KeyFn()
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description void
checkArguments(StaticContext env)
Method called during static type checkingint
computeSpecialProperties()
Get the static properties of this expression (other than its type).static KeyFn
internalKeyCall(NamePool pool, int fingerprint, java.lang.String name, Expression value, Expression doc)
Non-standard constructor to create an internal call on key() with a known key fingerprintSequenceIterator
iterate(XPathContext context)
Enumerate the results of the expressionExpression
preEvaluate(StaticContext env)
preEvaluate: this method suppresses compile-time evaluation by doing nothingExpression
simplify(StaticContext env)
Simplify: add a third implicit argument, the context documentExpression
typeCheck(StaticContext env, ItemType contextItemType)
Type-check the expression.-
Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, computeCardinality, 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, promote, replaceSubExpression, setArguments, setFunctionNameCode, simplifyArguments
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Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
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Method Detail
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typeCheck
public Expression typeCheck(StaticContext env, ItemType contextItemType) throws XPathException
Type-check the expression. This also calls preEvaluate() to evaluate the function if all the arguments are constant; functions that do not require this behavior can override the preEvaluate method.- Specified by:
typeCheck
in interfaceExpression
- Overrides:
typeCheck
in classFunctionCall
- Parameters:
env
- the static context of the expressioncontextItemType
- 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 to perform necessary run-time type checks, and to perform other type-related optimizations
- Throws:
StaticError
- if an error is discovered during this phase (typically a type error)XPathException
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internalKeyCall
public static KeyFn internalKeyCall(NamePool pool, int fingerprint, java.lang.String name, Expression value, Expression doc)
Non-standard constructor to create an internal call on key() with a known key fingerprint
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simplify
public Expression simplify(StaticContext env) throws XPathException
Simplify: add a third implicit argument, the context document- Specified by:
simplify
in interfaceExpression
- Overrides:
simplify
in classFunctionCall
- Parameters:
env
- the static context- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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checkArguments
public void checkArguments(StaticContext env) throws XPathException
Description copied from class:SystemFunction
Method called during static type checking- Overrides:
checkArguments
in classSystemFunction
- Throws:
XPathException
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computeSpecialProperties
public int computeSpecialProperties()
Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if a property bit is set, it is true, but if it is unset, the value is unknown.- Overrides:
computeSpecialProperties
in classSystemFunction
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preEvaluate
public Expression preEvaluate(StaticContext env)
preEvaluate: this method suppresses compile-time evaluation by doing nothing- Overrides:
preEvaluate
in classFunctionCall
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iterate
public SequenceIterator iterate(XPathContext context) throws XPathException
Enumerate the results of the expression- Specified by:
iterate
in interfaceExpression
- Overrides:
iterate
in classComputedExpression
- Parameters:
context
- supplies the context for evaluation- Returns:
- a SequenceIterator that can be used to iterate over the result of the expression
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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