net.sf.saxon.functions

Class TreatFn

java.lang.Object

net.sf.saxon.om.AbstractItem

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.TreatFn

All Implemented Interfaces:

PullEvent, Callable, Function, GroundedValue, Item, Sequence

Direct Known Subclasses:

TreatFn.ExactlyOne, TreatFn.OneOrMore, TreatFn.ZeroOrOne

public abstract class TreatFn
extends SystemFunction
implements Callable

This class supports the XPath 2.0 functions exactly-one(), one-or-more(), zero-or-one(). Because Saxon doesn't do strict static type checking, these are essentially identity functions; the run-time type checking is done as part of the function call mechanism

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	TreatFn.ExactlyOne
static class	TreatFn.OneOrMore
static class	TreatFn.ZeroOrOne

Constructor Summary

Constructors

Constructor and Description
TreatFn()

Method Summary

Methods

Modifier and Type	Method and Description
Sequence	call(XPathContext context, Sequence[] arguments) Call the Callable.
abstract String	getErrorCodeForTypeErrors() Return the error code to be used for type errors
abstract int	getRequiredCardinality()
StreamingAdjunct	getStreamingAdjunct() Get a class that supports streamed evaluation of this expression
RoleDiagnostic	makeRoleDiagnostic()

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

equals, export, exportAttributes, getArity, getCardinality, getContextNode, getDescription, getDetails, getExpressionCompiler, getFunctionItemType, getFunctionName, getIntegerBounds, getOperandRoles, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, importAttributes, makeCall, makeFunction, makeFunctionCall, makeOptimizedFunctionCall, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, supplyTypeInformation, typeCheckCaller

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

atomize, deepEquals, effectiveBooleanValue, getStringValue, getStringValueCS, isArray, isMap, optimize, simplify, typeCheck

Methods inherited from class net.sf.saxon.om.AbstractItem

getLength, head, 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

TreatFn

public TreatFn()

Method Detail

getErrorCodeForTypeErrors

public abstract String getErrorCodeForTypeErrors()

Return the error code to be used for type errors

Overrides:

getErrorCodeForTypeErrors in class SystemFunction

Returns:

the error code to be used for type errors in the function call. Normally XPTY0004, but different codes are used for functions such as exactly-one()

getRequiredCardinality

public abstract int getRequiredCardinality()

call

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

Description copied from interface: Callable

Call the Callable.

Specified by:

call in interface Callable

Specified by:

call in interface Function

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

makeRoleDiagnostic

public RoleDiagnostic makeRoleDiagnostic()

getStreamingAdjunct

public StreamingAdjunct getStreamingAdjunct()

Description copied from class: SystemFunction

Get a class that supports streamed evaluation of this expression

Overrides:

getStreamingAdjunct in class SystemFunction

Returns:

the relevant StreamingAdjunct, or null if none is available