com.saxonica.functions.hof

Class FunctionLookup

java.lang.Object

net.sf.saxon.om.AbstractItem

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.ContextAccessorFunction

com.saxonica.functions.hof.FunctionLookup

All Implemented Interfaces:

Callable, Function, GroundedValue, Item, Sequence

public class FunctionLookup
extends ContextAccessorFunction

This class supports the function-lookup() function in XPath 3.0. It takes as arguments a function name (QName) and arity, and returns a function item representing that function if found, or an empty sequence if not found.

Constructor Summary

Constructors

Constructor and Description
FunctionLookup()

Method Summary

Modifier and Type	Method and Description
Function	bindContext(XPathContext context) Bind a context item to appear as part of the function's closure.
Sequence	call(XPathContext context, Sequence[] arguments) Evaluate the expression
boolean	equals(java.lang.Object o) Determine whether two expressions are equivalent
Function	lookup(StructuredQName name, int arity, XPathContext context)
Expression	makeFunctionCall(Expression... arguments) Make an expression that either calls this function, or that is equivalent to a call on this function

Methods inherited from class net.sf.saxon.functions.SystemFunction

dependsOnContextItem, dynamicCall, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getCardinality, getCompilerName, getContextNode, getDescription, getDetails, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getIntegerBounds, getNetCost, getOperandRoles, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, getStreamerName, importAttributes, isTrustedResultType, makeCall, makeFunction, makeOptimizedFunctionCall, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, supplyTypeInformation, 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 net.sf.saxon.om.AbstractItem

getLength, head, isStreamed, itemAt, iterate, reduce, subsequence

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface net.sf.saxon.om.Function

iterate

Methods inherited from interface net.sf.saxon.om.Item

head

Methods inherited from interface net.sf.saxon.om.GroundedValue

getLength, head, itemAt, reduce, subsequence

Constructor Detail

FunctionLookup

public FunctionLookup()

Method Detail

makeFunctionCall

public Expression makeFunctionCall(Expression... arguments)

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 class SystemFunction

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

equals

public boolean equals(java.lang.Object o)

Determine whether two expressions are equivalent

Overrides:

equals in class SystemFunction

bindContext

public Function bindContext(XPathContext context)
                     throws XPathException

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 class ContextAccessorFunction

Parameters:

context - the context to which the function applies. Must not be null.

Throws:

XPathException

lookup

public Function lookup(StructuredQName name,
                       int arity,
                       XPathContext context)
                throws XPathException

Throws:

XPathException

call

public Sequence call(XPathContext context,
                     Sequence[] arguments)
              throws XPathException

Evaluate the expression

Specified by:

call in interface Callable

Specified by:

call in interface Function

Overrides:

call in class ContextAccessorFunction

Parameters:

context - the dynamic evaluation context

arguments - the values of the arguments, supplied as SequenceIterators

Returns:

the result of the evaluation, in the form of a SequenceIterator

Throws:

XPathException - if a dynamic error occurs during the evaluation of the expression