net.sf.saxon.query

Class ImportedFunctionLibrary

Implemented Interfaces:
FunctionLibrary, Serializable, FunctionLibrary, XQueryFunctionBinder

public class ImportedFunctionLibrary
extends java.lang.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.

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

Constructor Details

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 Details

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.

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.

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

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

setImportingModule

public void setImportingModule(QueryModule importingModule)
Set the module that imports this function libary
Parameters:
importingModule - the importing module