net.sf.saxon.functions
Class ExtensionFunctionCall

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.FunctionCall
          net.sf.saxon.functions.ExtensionFunctionCall

All Implemented Interfaces:

Serializable, SourceLocator, Container, EvaluableItem, SequenceIterable, InstructionInfoProvider

public class ExtensionFunctionCall
extends FunctionCall

This class acts as a container for an extension function defined to call a method in a user-defined class.

Note that the binding of an XPath function call to a Java method is done in class JavaExtensionLibrary

See Also:

Serialized Form

Field Summary

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

ExtensionFunctionCall()
Default constructor

Method Summary

void	checkArguments(StaticContext env) Method called by the expression parser when all arguments have been supplied
int	computeCardinality()
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.
Class	getTargetClass() Get the class containing the method being called
AccessibleObject	getTargetMethod() Get the target method (or field, or constructor) being called
void	init(int nameCode, Class theClass, AccessibleObject object, Configuration config) Initialization: creates an ExtensionFunctionCall
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)
static String	toCamelCase(String name, boolean debug, PrintStream diag) Convert a name to camelCase (by removing hyphens and changing the following letter to capitals)
boolean	usesFocus() Determine whether this method uses the focus.

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

ExtensionFunctionCall

public ExtensionFunctionCall()

Default constructor

Method Detail

init

public void init(int nameCode,
                 Class theClass,
                 AccessibleObject object,
                 Configuration config)

Initialization: creates an ExtensionFunctionCall

Parameters:

nameCode - the name code of the function, for display purposes

theClass - the Java class containing the method to be called

object - the method, field, or constructor of the Java class to be called

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. The result is a bitwise-or'ed value composed from constants such as XPathContext.VARIABLES and XPathContext.CURRENT_NODE

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.

getTargetClass

public Class getTargetClass()

Get the class containing the method being called

getTargetMethod

public AccessibleObject getTargetMethod()

Get the target method (or field, or constructor) being called

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()

usesFocus

public boolean usesFocus()

Determine whether this method uses the focus. True if the first argument is of type XPathContext.

toCamelCase

public static String toCamelCase(String name,
                                 boolean debug,
                                 PrintStream diag)

Convert a name to camelCase (by removing hyphens and changing the following letter to capitals)

Parameters:

name - the name to be converted to camelCase

debug - true if tracing is required

Returns:

the camelCased name