net.sf.saxon.xpath
Class XPathFunctionCall

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.FunctionCall
          net.sf.saxon.xpath.XPathFunctionCall

All Implemented Interfaces:

Serializable, SourceLocator, Container, EvaluableItem, SequenceIterable, InstructionInfoProvider

public class XPathFunctionCall
extends FunctionCall

This class is an expression that calls an external function supplied using the JAXP XPathFunction interface

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.Expression

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

XPathFunctionCall(XPathFunction function)
Default constructor

Method Summary

SequenceIterator	call(ValueRepresentation[] argValues, XPathContext context) Call an extension function previously identified using the bind() method.
void	checkArguments(StaticContext env) Method called by the expression parser when all arguments have been supplied
int	computeCardinality() Determine the cardinality of the result
int	getIntrinsicDependencies() Determine which aspects of the context the expression depends on.
ItemType	getItemType(TypeHierarchy th) Determine the data type of the expression, if possible.
SequenceIterator	iterate(XPathContext context) Evaluate the function.
Expression	preEvaluate(StaticContext env) preEvaluate: this method suppresses compile-time evaluation by doing nothing (because the external function might have side-effects and might use the context)

Methods inherited from class net.sf.saxon.expr.FunctionCall

display, getArguments, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, optimize, promote, replaceSubExpression, setArguments, setFunctionNameCode, simplify, typeCheck

Methods inherited from class net.sf.saxon.expr.Expression

adoptChildExpression, checkPermittedContents, computeDependencies, computeSpecialProperties, computeStaticProperties, doPromotion, effectiveBooleanValue, evaluateAsString, evaluateItem, getCardinality, getColumnNumber, getContainingProcedure, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

XPathFunctionCall

public XPathFunctionCall(XPathFunction function)

Default constructor

Method Detail

preEvaluate

public Expression preEvaluate(StaticContext env)

preEvaluate: this method suppresses compile-time evaluation by doing nothing (because the external function might have side-effects and might use the context)

Overrides:

preEvaluate in class FunctionCall

checkArguments

public void checkArguments(StaticContext env)
                    throws XPathException

Method called by the expression parser when all arguments have been supplied

Throws:

XPathException

getIntrinsicDependencies

public int getIntrinsicDependencies()

Determine which aspects of the context the expression depends on. XPath external functions are given no access to context information so they cannot have any dependencies on it.

Overrides:

getIntrinsicDependencies in class Expression

Returns:

a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

iterate

public SequenceIterator iterate(XPathContext context)
                         throws XPathException

Evaluate the function.

Specified by:

iterate in interface SequenceIterable

Overrides:

iterate in class Expression

Parameters:

context - The context in which the function is to be evaluated

Returns:

a Value representing the result of the function.

Throws:

XPathException - if the function cannot be evaluated.

call

public SequenceIterator call(ValueRepresentation[] argValues,
                             XPathContext context)
                      throws XPathException

Call an extension function previously identified using the bind() method. A subclass can override this method.

Parameters:

argValues - The values of the arguments

Returns:

The value returned by the extension function

Throws:

XPathException

getItemType

public ItemType getItemType(TypeHierarchy th)

Determine the data type of the expression, if possible. All expressions return sequences, in general; this method determines the type of the items within the sequence, assuming that (a) this is known in advance, and (b) it is the same for all items in the sequence.

This method will always return a result, though it may be the best approximation that is available at the time.

Specified by:

getItemType in class Expression

Parameters:

th -

Returns:

the item type

computeCardinality

public int computeCardinality()

Determine the cardinality of the result

Returns:

ZERO_OR_MORE (we don't know)