net.sf.saxon.query
Class ImportedFunctionLibrary

java.lang.Object
  net.sf.saxon.query.ImportedFunctionLibrary

All Implemented Interfaces:

Serializable, FunctionLibrary, XQueryFunctionBinder

public class ImportedFunctionLibrary
extends Object
implements FunctionLibrary, XQueryFunctionBinder

This implementation of FunctionLibrary contains all the functions imported into a Query Module. It is implemented as a view of the "global" XQueryFunctionLibrary for the whole query, selecting only those functions that are in an imported namespace.

See Also:

Serialized Form

Constructor Summary

ImportedFunctionLibrary(QueryModule importingModule, XQueryFunctionLibrary baseLibrary)
Create an imported function library

Method Summary

void	addImportedNamespace(String namespace) Add an imported namespace
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.
XQueryFunction	getDeclaration(StructuredQName functionName, Expression[] staticArgs) Get the function declaration corresponding to a given function name and arity
boolean	isAvailable(StructuredQName functionName, int arity) Test whether an extension function with a given name and arity is available.
void	setImportingModule(QueryModule importingModule) Set the module that imports this function libary

Methods inherited from class java.lang.Object

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

Constructor Detail

ImportedFunctionLibrary

public ImportedFunctionLibrary(QueryModule importingModule,
                               XQueryFunctionLibrary baseLibrary)

Create an imported function library

Parameters:

importingModule - the module importing the library

baseLibrary - the function library of which this is a subset view

Method Detail

addImportedNamespace

public void addImportedNamespace(String namespace)

Add an imported namespace

Parameters:

namespace - the imported namespace

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 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 -

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.

getDeclaration

public XQueryFunction getDeclaration(StructuredQName functionName,
                                     Expression[] staticArgs)

Get the function declaration corresponding to a given function name and arity

Specified by:

getDeclaration in interface XQueryFunctionBinder

Parameters:

functionName - the name of the function as a QName

staticArgs - the expressions supplied as arguments in the function call (typically, we only need to know the number of arguments)

Returns:

the XQueryFunction if there is one, or null if not.

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.

setImportingModule

public void setImportingModule(QueryModule importingModule)

Set the module that imports this function libary

Parameters:

importingModule - the importing module

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. 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:

isAvailable in interface FunctionLibrary

Parameters:

functionName - the name of the function in question

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.