net.sf.saxon.functions
Class SystemFunctionLibrary

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

All Implemented Interfaces:

Serializable, FunctionLibrary

public class SystemFunctionLibrary
extends Object
implements FunctionLibrary

The SystemFunctionLibrary represents the collection of functions in the fn: namespace. That is, the functions defined in the "Functions and Operators" specification, optionally augmented by the additional functions defined in XSLT.

See Also:

Serialized Form

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.
SequenceType[]	getFunctionSignature(StructuredQName functionName, int arity) Test whether a function with a given name and arity is available; if so, return its signature.
static SystemFunctionLibrary	getSystemFunctionLibrary(int functionSet) Factory method to create or get a SystemFunctionLibrary

Methods inherited from class java.lang.Object

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

Method Detail

getSystemFunctionLibrary

public static SystemFunctionLibrary getSystemFunctionLibrary(int functionSet)

Factory method to create or get a SystemFunctionLibrary

Parameters:

functionSet - determines the set of functions allowed. One or more of the bit settings StandardFunction.CORE, StandardFunction.XSLT, StandardFunction.XQUPDATE, etc

Returns:

the appropriate SystemFunctionLibrary

getFunctionSignature

public SequenceType[] getFunctionSignature(StructuredQName functionName,
                                           int arity)

Test whether a function with a given name and arity is available; if so, return its signature. This supports the function-available() function in XSLT; it is also used to support higher-order functions introduced in XQuery 1.1.

This method may be called either at compile time or at run time. If the function library is to be used only in an XQuery or free-standing XPath environment, this method may throw an UnsupportedOperationException.

Specified by:

getFunctionSignature in interface FunctionLibrary

Parameters:

functionName - the qualified name of the function being called

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 a zero-length array if there is some function of this name available for calling.

Returns:

if a function of this name and arity is available for calling, then the type signature of the function, as an array of sequence types in which the zeroth entry represents the return type; or a zero-length array if the function exists but the signature is not known; or null if the function does not exist

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 name of the function to be bound

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 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; or if this function library "owns" the namespace containing the function call, but no function was found.

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.