net.sf.saxon.functions
Class JavaExtensionLibrary

java.lang.Object
  net.sf.saxon.functions.JavaExtensionLibrary

All Implemented Interfaces:

Serializable, FunctionLibrary

public class JavaExtensionLibrary
extends Object
implements FunctionLibrary

The JavaExtensionLibrary is a FunctionLibrary that binds XPath function calls to calls on Java methods (or constructors, or fields). It performs a mapping from the namespace URI of the function to the Java class (the mapping is partly table driven and partly algorithmic), and maps the local name of the function to the Java method, constructor, or field within the class. If the Java methods are polymorphic, then it tries to select the appropriate method based on the static types of the supplied arguments. Binding is done entirely at XPath compilation time.

See Also:

Serialized Form

Constructor Summary

JavaExtensionLibrary(Configuration config)
Construct a JavaExtensionLibrary and establish the default uri->class mappings.

Method Summary

Expression	bind(StructuredQName 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.
void	declareJavaClass(String uri, Class theClass) Declare a mapping from a specific namespace URI to a Java class
boolean	isAvailable(StructuredQName functionName, int arity) Test whether an extension function with a given name and arity is available.

Methods inherited from class java.lang.Object

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

Constructor Detail

JavaExtensionLibrary

public JavaExtensionLibrary(Configuration config)

Construct a JavaExtensionLibrary and establish the default uri->class mappings.

Parameters:

config - The Saxon configuration

Method Detail

declareJavaClass

public void declareJavaClass(String uri,
                             Class theClass)

Declare a mapping from a specific namespace URI to a Java class

Parameters:

uri - the namespace URI of the function name

theClass - the Java class that implements the functions in this namespace

isAvailable

public boolean isAvailable(StructuredQName functionName,
                           int arity)

Test whether an extension function with a given name and arity is available. This supports the function-available() function in XSLT. This method may be called either at compile time or at run time.

Specified by:

isAvailable in interface FunctionLibrary

Parameters:

functionName - The qualified name of the extension function

arity - The number of arguments. This is set to -1 in the case of the single-argument function-available() function; in this case the method should return true if there is some

Returns:

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

bind

public Expression bind(StructuredQName 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 qualified name of the function being called

staticArgs - The expressions supplied statically in the function call. The intention is that the static type of the arguments (obtainable via getItemType() and getCardinality()) may be used as part of the binding algorithm.

env -

Returns:

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

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.

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.