## 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, Container container)` 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,
                           Container container)
                    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` -
    `container` -
  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.

Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.