Package net.sf.saxon.functions
Class ConstantFunction
java.lang.Object
net.sf.saxon.functions.AbstractFunction
net.sf.saxon.functions.SystemFunction
net.sf.saxon.functions.ConstantFunction
- All Implemented Interfaces:
Callable
,Function
,GroundedValue
,Item
,Sequence
- Direct Known Subclasses:
ConstantFunction.False
,ConstantFunction.True
A ConstantFunction is a zero-argument function that always delivers the same result, supplied
at the time the function is instantiated.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
static class
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Field Summary
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptioncall
(XPathContext context, Sequence[] arguments) Invoke the functionFor a function that returns an integer or a sequence of integers, get a lower and upper bound on the values of the integers that may be returned, from static analysis.makeFunctionCall
(Expression[] arguments) Make an expression that either calls this function, or that is equivalent to a call on this functionMethods inherited from class net.sf.saxon.functions.SystemFunction
dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getCardinality, getCompilerName, getContextNode, getDescription, getDetails, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getNetCost, getOperandRoles, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, getStreamerName, importAttributes, isTrustedResultType, makeCall, makeFunction, makeOptimizedFunctionCall, 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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Field Details
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value
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Constructor Details
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ConstantFunction
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Method Details
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call
Description copied from interface:Function
Invoke the function- Parameters:
context
- the XPath dynamic evaluation contextarguments
- the actual arguments to be supplied- Returns:
- the result of invoking the function
- Throws:
XPathException
- if a dynamic error occurs within the function
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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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getIntegerBounds
Description copied from class:SystemFunction
For a function that returns an integer or a sequence of integers, get a lower and upper bound on the values of the integers that may be returned, from static analysis. The default implementation returns null, meaning "unknown" or "not applicable". Other implementations return an array of two IntegerValue objects, representing the lower and upper bounds respectively. The values UNBOUNDED_LOWER and UNBOUNDED_UPPER are used by convention to indicate that the value may be arbitrarily large. The values MAX_STRING_LENGTH and MAX_SEQUENCE_LENGTH are used to indicate values limited by the size of a string or the size of a sequence.- Overrides:
getIntegerBounds
in classSystemFunction
- Returns:
- the lower and upper bounds of integer values in the result, or null to indicate unknown or not applicable.
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