net.sf.saxon.query

Class XQueryFunctionLibrary

Implemented Interfaces:
FunctionLibrary, Serializable, FunctionLibrary, XQueryFunctionBinder

public class XQueryFunctionLibrary
extends java.lang.Object
implements FunctionLibrary, XQueryFunctionBinder

An XQueryFunctionLibrary is a function library containing all the user-defined functions available for use within a particular XQuery module: that is, the functions declared in that module, and the functions imported from other modules. It also contains (transiently during compilation) a list of function calls within the module that have not yet been bound to a specific function declaration.

Constructor Summary

XQueryFunctionLibrary(Configuration config)
Create an XQueryFunctionLibrary

Method Summary

Expression
bind(StructuredQName functionName, Expression[] arguments, StaticContext env)
Identify a (namespace-prefixed) function appearing in the expression.
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
declareFunction(XQueryFunction function)
Register a user-defined XQuery function
void
explainGlobalFunctions(ExpressionPresenter out)
Output "explain" information about each declared function
protected void
fixupGlobalFunctions(QueryModule env)
Fixup all references to global functions.
Configuration
getConfiguration()
Get the Configuration options
XQueryFunction
getDeclaration(StructuredQName functionName, Expression[] staticArgs)
Get the function declaration corresponding to a given function name and arity
XQueryFunction
getDeclarationByKey(String functionKey)
Get the function declaration corresponding to a given function name and arity, supplied in the form "{uri}local/arity"
Iterator
getFunctionDefinitions()
Get an iterator over the Functions defined in this module
UserFunction
getUserDefinedFunction(String uri, String localName, int arity)
Get the function with a given name and arity.
boolean
isAvailable(StructuredQName functionName, int arity)
Test whether a function with a given name and arity is available.
protected void
optimizeGlobalFunctions()
Optimize the body of all global functions.
void
setConfiguration(Configuration config)
Set the Configuration options

Constructor Details

XQueryFunctionLibrary

public XQueryFunctionLibrary(Configuration config)
Create an XQueryFunctionLibrary
Parameters:
config - the Saxon configuration

Method Details

bind

public Expression bind(StructuredQName functionName,
                       Expression[] arguments,
                       StaticContext env)
            throws XPathException
Identify a (namespace-prefixed) function appearing in the expression. This method is called by the XQuery parser to resolve function calls found within the query.

Note that a function call may appear earlier in the query than the definition of the function to which it is bound. Unlike XSLT, we cannot search forwards to find the function definition. Binding of function calls is therefore a two-stage process; at the time the function call is parsed, we simply register it as pending; subsequently at the end of query parsing all the pending function calls are resolved. Another consequence of this is that we cannot tell at the time a function call is parsed whether it is a call to an internal (XSLT or XQuery) function or to an extension function written in Java.

Specified by:
bind in interface FunctionLibrary
Returns:
an Expression representing the function call. This will normally be a FunctionCall, but it may be rewritten as some other expression.
Throws:
XPathException - if the function call is invalid, either because it is an unprefixed call to a non-system function, or because it is calling a system function that is available in XSLT only. A prefixed function call that cannot be recognized at this stage is assumed to be a forwards reference, and is bound later when bindUnboundFunctionCalls() is called.

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.

declareFunction

public void declareFunction(XQueryFunction function)
            throws XPathException
Register a user-defined XQuery function
Parameters:
function - the function to be registered
Throws:
XPathException - if there is an existing function with the same name and arity

explainGlobalFunctions

public void explainGlobalFunctions(ExpressionPresenter out)
Output "explain" information about each declared function
Parameters:
out - the ExpressionPresenter that renders the output

fixupGlobalFunctions

protected void fixupGlobalFunctions(QueryModule env)
            throws XPathException
Fixup all references to global functions. This method is called on completion of query parsing. Each XQueryFunction is required to bind all references to that function to the object representing the run-time executable code of the function.

This method is for internal use.

Parameters:
env - the static context for the main query body.

getConfiguration

public Configuration getConfiguration()
Get the Configuration options
Returns:
the Saxon configuration

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.

getDeclarationByKey

public XQueryFunction getDeclarationByKey(String functionKey)
Get the function declaration corresponding to a given function name and arity, supplied in the form "{uri}local/arity"
Parameters:
functionKey - a string in the form "{uri}local/arity" identifying the required function
Returns:
the XQueryFunction if there is one, or null if not.

getFunctionDefinitions

public Iterator getFunctionDefinitions()
Get an iterator over the Functions defined in this module
Returns:
an Iterator, whose items are XQueryFunction objects. It returns all function known to this module including those imported from elsewhere; they can be distinguished by their namespace.

getUserDefinedFunction

public UserFunction getUserDefinedFunction(String uri,
                                           String localName,
                                           int arity)
Get the function with a given name and arity. This method is provided so that XQuery functions can be called directly from a Java application. Note that there is no type checking or conversion of arguments when this is done: the arguments must be provided in exactly the form that the function signature declares them.
Parameters:
uri - the uri of the function name
localName - the local part of the function name
arity - the number of arguments.
Returns:
the function identified by the URI, local name, and arity; or null if there is no such function

isAvailable

public boolean isAvailable(StructuredQName functionName,
                           int arity)
Test whether a 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 QName identifying the 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

optimizeGlobalFunctions

protected void optimizeGlobalFunctions()
            throws XPathException
Optimize the body of all global functions. This may involve inlining functions calls

setConfiguration

public void setConfiguration(Configuration config)
Set the Configuration options
Parameters:
config - the Saxon configuration