Package net.sf.saxon.functions
Class Empty
java.lang.Object
net.sf.saxon.functions.AbstractFunction
net.sf.saxon.functions.SystemFunction
net.sf.saxon.functions.Aggregate
net.sf.saxon.functions.Empty
- All Implemented Interfaces:
Callable
,Function
,GroundedValue
,Item
,Sequence
Implementation of the fn:empty function
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptioncall
(XPathContext context, Sequence[] arguments) Evaluate the expressionGet the (local) name of a class that can be used to generate bytecode for this system functionGet a name that identifies the class that can be used to evaluate this function in streaming mode, that is, supplying one item or event at a time as it is delivered by the parser.makeFunctionCall
(Expression[] arguments) Make an expression that either calls this function, or that is equivalent to a call on this functionmakeOptimizedFunctionCall
(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo, Expression... arguments) Allow the function to create an optimized call based on the values of the actual argumentsMethods inherited from class net.sf.saxon.functions.SystemFunction
dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getCardinality, getContextNode, getDescription, getDetails, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getIntegerBounds, getNetCost, getOperandRoles, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, importAttributes, isTrustedResultType, makeCall, makeFunction, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, supplyTypeInformation, toShortString, toString, typeCheckCaller
Methods inherited from class net.sf.saxon.functions.AbstractFunction
atomize, deepEquals, effectiveBooleanValue, getAnnotations, getStringValue, getStringValueCS, isArray, isMap, makeNewContext, simplify, typeCheck
Methods inherited from class java.lang.Object
clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface net.sf.saxon.om.GroundedValue
asIterable, concatenate, containsNode, materialize
Methods inherited from interface net.sf.saxon.om.Item
getLength, head, isStreamed, itemAt, iterate, reduce, subsequence
Methods inherited from interface net.sf.saxon.om.Sequence
makeRepeatable
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Constructor Details
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Empty
public Empty()
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Method Details
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makeOptimizedFunctionCall
public Expression makeOptimizedFunctionCall(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo, Expression... arguments) throws XPathException Description copied from class:SystemFunction
Allow the function to create an optimized call based on the values of the actual arguments- Overrides:
makeOptimizedFunctionCall
in classSystemFunction
- Parameters:
visitor
- the expression visitorcontextInfo
- information about the context itemarguments
- the supplied arguments to the function call. Note: modifying the contents of this array should not be attempted, it is likely to have no effect.- Returns:
- either a function call on this function, or an expression that delivers the same result, or null indicating that no optimization has taken place
- Throws:
XPathException
- if an error is detected
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call
Evaluate the expression- Parameters:
context
- the dynamic evaluation contextarguments
- the values of the arguments, supplied as Sequences- Returns:
- the result of the evaluation, in the form of a Sequence
- Throws:
XPathException
- if a dynamic error occurs during the evaluation of the expression
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makeFunctionCall
Description copied from class:SystemFunction
Make an expression that either calls this function, or that is equivalent to a call on this function- Overrides:
makeFunctionCall
in classSystemFunction
- Parameters:
arguments
- the supplied arguments to the function call- Returns:
- either a function call on this function, or an expression that delivers the same result
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getCompilerName
Description copied from class:SystemFunction
Get the (local) name of a class that can be used to generate bytecode for this system function- Overrides:
getCompilerName
in classSystemFunction
- Returns:
- the name of a bytecode generation class, or null if there is no bytecode support for this function
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getStreamerName
Description copied from class:SystemFunction
Get a name that identifies the class that can be used to evaluate this function in streaming mode, that is, supplying one item or event at a time as it is delivered by the parser. Special streaming support is generally available in Saxon-EE for all system functions that take a sequence as their argument.- Overrides:
getStreamerName
in classSystemFunction
- Returns:
- a name that identifies a class that supports streamed evaluation of this system
function, or null if no such class is available. The mapping of names to classes is
defined in the Saxon-EE class
StreamerMap
. In non-streaming Saxon editions (HE and PE) the method always returns null.
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