Package net.sf.saxon.functions

Class HeadFn

java.lang.Object

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.HeadFn

All Implemented Interfaces:

Callable, ArityOneFunction, IFunctionWithRetainedParameterNames, FunctionItem, GroundedValue, Item, Sequence

public class HeadFn
extends SystemFunction
implements ArityOneFunction

This class implements the function fn:head(), which is a standard function in XPath 3.0

Constructor Summary

Constructors

Constructor	Description
HeadFn()

Method Summary

Modifier and Type	Method	Description
Sequence	call(XPathContext context, Sequence[] arguments)	Evaluate the expression
Sequence	call1(XPathContext context, Sequence arg0)	Call a function with one argument
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, equals, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getCardinality, getContextNode, getDescription, getDetails, getElaborator, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getNetCost, getOperandRoles, getParameterNames, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, getStreamerName, getUniqueIdentifier, getUniStringArg, hashCode, importAttributes, isSequenceVariadic, isTrustedResultType, makeCall, makeFunction, makeFunction40, makeOptimizedFunctionCall, makeTrueFunctionCall, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, supplyTypeInformation, 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

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

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

makeRepeatable

Constructor Details

HeadFn

public HeadFn()

Method Details

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

call

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

Evaluate the expression

Specified by:

call in interface Callable

Parameters:

context - the dynamic evaluation context

arguments - 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

call1

public Sequence call1(XPathContext context,
 Sequence arg0)
               throws XPathException

Description copied from interface: ArityOneFunction

Call a function with one argument

Specified by:

call1 in interface ArityOneFunction

Parameters:

context - the dynamic evaluation context

arg0 - the first argument

Returns:

the result of the function call

Throws:

XPathException - if the call fails with a dynamic error