net.sf.saxon.functions

Class IntegratedFunctionLibrary

java.lang.Object

net.sf.saxon.functions.IntegratedFunctionLibrary

All Implemented Interfaces:

FunctionLibrary

public class IntegratedFunctionLibrary
extends java.lang.Object
implements FunctionLibrary

A library of integrated function calls, that is, user-written extension functions implemented as instances of the class IntegratedFunction.

Constructor Summary

Constructors

Constructor and Description
IntegratedFunctionLibrary()

Method Summary

Modifier and Type	Method and Description
Expression	bind(SymbolicName.F functionName, Expression[] staticArgs, StaticContext env) Bind an extension function, given the URI and local parts of the function name, and the list of expressions supplied as arguments.
FunctionLibrary	copy() This method creates a copy of a FunctionLibrary: if the original FunctionLibrary allows new functions to be added, then additions to this copy will not affect the original, or vice versa.
Function	getFunctionItem(SymbolicName.F functionName, StaticContext staticContext) Test whether a function with a given name and arity is available; if so, return a function item that can be dynamically called.
boolean	isAvailable(SymbolicName.F functionName) Test whether a function with a given name and arity is available
static Expression	makeFunctionCall(ExtensionFunctionDefinition defn, Expression[] staticArgs)
void	registerFunction(ExtensionFunctionDefinition function) Register an integrated function with this function library

Methods inherited from class java.lang.Object

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

Constructor Detail

IntegratedFunctionLibrary

public IntegratedFunctionLibrary()

Method Detail

registerFunction

public void registerFunction(ExtensionFunctionDefinition function)

Register an integrated function with this function library

Parameters:

function - the implementation of the function (or set of functions)

bind

public Expression bind(SymbolicName.F functionName,
                       Expression[] staticArgs,
                       StaticContext env)
                throws XPathException

Bind an extension function, given the URI and local parts of the function name, and the list of expressions supplied as arguments. This method is called at compile time.

Specified by:

bind in interface FunctionLibrary

Parameters:

functionName - the QName and arity of the function being called

staticArgs - The expressions supplied statically in arguments to the function call. The length of this array represents the arity of the function. The intention is that the static type of the arguments (obtainable via getItemType() and getCardinality()) may be used as part of the binding algorithm. In some cases it may be possible for the function to be pre-evaluated at compile time, for example if these expressions are all constant values.

The conventions of the XPath language demand that the results of a function depend only on the values of the expressions supplied as arguments, and not on the form of those expressions. For example, the result of f(4) is expected to be the same as f(2+2). The actual expression is supplied here to enable the binding mechanism to select the most efficient possible implementation (including compile-time pre-evaluation where appropriate).

env - The static context of the function call

Returns:

An object representing the function to be called, if one is found; null if no function was found matching the required name and arity.

Throws:

XPathException - if a function is found with the required name and arity, but the implementation of the function cannot be loaded or used; or if an error occurs while searching for the function.

makeFunctionCall

public static Expression makeFunctionCall(ExtensionFunctionDefinition defn,
                                          Expression[] staticArgs)

getFunctionItem

public Function getFunctionItem(SymbolicName.F functionName,
                                StaticContext staticContext)
                         throws XPathException

Test whether a function with a given name and arity is available; if so, return a function item that can be dynamically called.

This supports the function-lookup() function in XPath 3.0.

Specified by:

getFunctionItem in interface FunctionLibrary

Parameters:

functionName - the qualified name of the function being called

staticContext - the static context to be used by the function, in the event that it is a system function with dependencies on the static context

Returns:

if a function of this name and arity is available for calling, then a corresponding function item; or null if the function does not exist

Throws:

XPathException - in the event of certain errors, for example attempting to get a function that is private

isAvailable

public boolean isAvailable(SymbolicName.F functionName)

Test whether a function with a given name and arity is available

This supports the function-available() function in XSLT.

Specified by:

isAvailable in interface FunctionLibrary

Parameters:

functionName - the qualified name of the function being called

Returns:

true if a function of this name and arity is available for calling

copy

public FunctionLibrary copy()

This method creates a copy of a FunctionLibrary: if the original FunctionLibrary allows new functions to be added, then additions to this copy will not affect the original, or vice versa.

Specified by:

copy in interface FunctionLibrary

Returns:

a copy of this function library. This must be an instance of the original class.