Package net.sf.saxon.functions
Class PositionAndLast
java.lang.Object
net.sf.saxon.functions.AbstractFunction
net.sf.saxon.functions.SystemFunction
net.sf.saxon.functions.ContextAccessorFunction
net.sf.saxon.functions.PositionAndLast
- All Implemented Interfaces:
Callable
,FunctionItem
,GroundedValue
,Item
,Sequence
- Direct Known Subclasses:
PositionAndLast.Last
,PositionAndLast.Position
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
static class
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionbindContext
(XPathContext context) Bind a context item to appear as part of the function's closure.call
(XPathContext context, Sequence[] arguments) Evaluate the expressionabstract Int64Value
Evaluate in a general contextFor an expression 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.int
Get an estimate of the net cost of evaluating the function, excluding the cost of evaluating its arguments.boolean
Ask whether the context item may possibly be undefinedvoid
supplyTypeInformation
(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo, Expression[] arguments) Method called during static type checking.Methods inherited from class net.sf.saxon.functions.SystemFunction
dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getCardinality, getContextNode, getDescription, getDetails, getElaborator, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getOperandRoles, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, getStreamerName, getUniStringArg, hashCode, importAttributes, isSequenceVariadic, isTrustedResultType, makeCall, makeFunction, makeFunction40, makeFunctionCall, makeOptimizedFunctionCall, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, toShortString, toString, typeCheckCaller
Methods inherited from class net.sf.saxon.functions.AbstractFunction
atomize, deepEqual40, deepEquals, effectiveBooleanValue, getAnnotations, getUnicodeStringValue, isArray, isMap, makeNewContext, simplify, typeCheck
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface net.sf.saxon.om.FunctionItem
getGenre
Methods inherited from interface net.sf.saxon.om.GroundedValue
asIterable, concatenate, containsNode, materialize
Methods inherited from interface net.sf.saxon.om.Item
getLength, getStringValue, 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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PositionAndLast
public PositionAndLast()
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Method Details
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getNetCost
public int getNetCost()Get an estimate of the net cost of evaluating the function, excluding the cost of evaluating its arguments. The result is 0 for very simple functions like position() and exists(), 1 by default, and higher values for particularly expensive functions.- Overrides:
getNetCost
in classSystemFunction
- Returns:
- the estimated cost
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bindContext
Bind a context item to appear as part of the function's closure. If this method has been called, the supplied context item will be used in preference to the context item at the point where the function is actually called.- Specified by:
bindContext
in classContextAccessorFunction
- Parameters:
context
- the context to which the function applies. Must not be null.
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getIntegerBounds
For an expression 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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supplyTypeInformation
public void supplyTypeInformation(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo, Expression[] arguments) throws XPathException Description copied from class:SystemFunction
Method called during static type checking. This method may be implemented in subclasses so that functions can take advantage of knowledge of the types of the arguments that will be supplied.- Overrides:
supplyTypeInformation
in classSystemFunction
- Parameters:
visitor
- an expression visitor, providing access to the static context and configurationcontextInfo
- information about whether the context item is set, and what its type isarguments
- the expressions appearing as arguments in the function call- Throws:
XPathException
- if an error is detected
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isContextPossiblyUndefined
public boolean isContextPossiblyUndefined()Ask whether the context item may possibly be undefined- Returns:
- true if it might be undefined
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evaluateItem
Evaluate in a general context- Throws:
XPathException
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call
Evaluate the expression- Specified by:
call
in interfaceCallable
- Overrides:
call
in classContextAccessorFunction
- 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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