Package net.sf.saxon.functions

Class AccumulatorFn

java.lang.Object

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.AccumulatorFn

All Implemented Interfaces:

Callable, IContextAccessorFunction, IFunctionWithRetainedParameterNames, FunctionItem, GroundedValue, Item, Sequence

Direct Known Subclasses:

AccumulatorFn.AccumulatorAfter, AccumulatorFn.AccumulatorBefore

public abstract class AccumulatorFn
extends SystemFunction
implements IContextAccessorFunction

Non-streaming implementation of accumulator-before() and accumulator-after()

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	AccumulatorFn.AccumulatorAfter
static class	AccumulatorFn.AccumulatorBefore
static enum	AccumulatorFn.Phase

Constructor Summary

Constructors

Constructor	Description
AccumulatorFn()

Method Summary

Modifier and Type	Method	Description
FunctionItem	bindContext(XPathContext context)	Bind context information to appear as part of the function's closure.
Sequence	call(XPathContext context, Sequence[] arguments)	Call the Callable.
boolean	dependsOnContext()	Ask whether this function is actually dependent on the dynamic context
int	getCardinality(Expression[] args)	Get the cardinality, given knowledge of the actual arguments
abstract AccumulatorFn.Phase	getPhase()
ItemType	getResultItemType(Expression[] args)	Get the return type, given knowledge of the actual arguments

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

dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getContextNode, getDescription, getDetails, getElaborator, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getNetCost, getOperandRoles, getParameterNames, getRequiredType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, getStreamerName, getUniqueIdentifier, getUniStringArg, hashCode, importAttributes, isSequenceVariadic, isTrustedResultType, makeCall, makeFunction, makeFunction40, makeFunctionCall, 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

AccumulatorFn

public AccumulatorFn()

Method Details

getPhase

public abstract AccumulatorFn.Phase getPhase()

dependsOnContext

public boolean dependsOnContext()

Description copied from interface: IContextAccessorFunction

Ask whether this function is actually dependent on the dynamic context

Specified by:

dependsOnContext in interface IContextAccessorFunction

Returns:

true if the function cannot be used unless the dynamic context is first bound

getResultItemType

public ItemType getResultItemType(Expression[] args)

Get the return type, given knowledge of the actual arguments

Overrides:

getResultItemType in class SystemFunction

Parameters:

args - the actual arguments supplied

Returns:

the best available item type that the function will return

getCardinality

public int getCardinality(Expression[] args)

Get the cardinality, given knowledge of the actual arguments

Overrides:

getCardinality in class SystemFunction

Parameters:

args - the actual arguments supplied

Returns:

the most precise available cardinality that the function will return

call

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

Call the Callable.

Specified by:

call in interface Callable

Parameters:

context - the dynamic evaluation context

arguments - the values of the arguments, supplied as Sequences.

Generally it is advisable, if calling iterate() to process a supplied sequence, to call it only once; if the value is required more than once, it should first be converted to a GroundedValue by calling the utility methd SequenceTool.toGroundedValue().

If the expected value is a single item, the item should be obtained by calling Sequence.head(): it cannot be assumed that the item will be passed as an instance of Item or AtomicValue.

It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.

Returns:

the result of the evaluation, in the form of a Sequence. It is the responsibility of the callee to ensure that the type of result conforms to the expected result type.

Throws:

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

bindContext

public FunctionItem bindContext(XPathContext context)
                         throws XPathException

Bind context information to appear as part of the function's closure. If this method has been called, the supplied context will be used in preference to the context at the point where the function is actually called.

Specified by:

bindContext in interface IContextAccessorFunction

Parameters:

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

Throws:

XPathException