net.sf.saxon.query

Class XQueryFunctionLibrary

public class XQueryFunctionLibrary extends 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
Expressionbind(StructuredQName functionName, Expression[] arguments, StaticContext env)
Identify a (namespace-prefixed) function appearing in the expression.
FunctionLibrarycopy()
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.
voiddeclareFunction(XQueryFunction function)
Register a user-defined XQuery function
voidexplainGlobalFunctions(ExpressionPresenter out)
Output "explain" information about each declared function
protected voidfixupGlobalFunctions(QueryModule env)
Fixup all references to global functions.
ConfigurationgetConfiguration()
Get the Configuration options
XQueryFunctiongetDeclaration(StructuredQName functionName, Expression[] staticArgs)
Get the function declaration corresponding to a given function name and arity
XQueryFunctiongetDeclarationByKey(String functionKey)
Get the function declaration corresponding to a given function name and arity, supplied in the form "{uri}local/arity"
Iterator<XQueryFunction>getFunctionDefinitions()
Get an iterator over the Functions defined in this module
SequenceType[]getFunctionSignature(StructuredQName functionName, int arity)
Test whether a function with a given name and arity is available; if so, return its signature.
UserFunctiongetUserDefinedFunction(String uri, String localName, int arity)
Get the function with a given name and arity.
protected voidoptimizeGlobalFunctions()
Optimize the body of all global functions.
voidsetConfiguration(Configuration config)
Set the Configuration options

Constructor Detail

XQueryFunctionLibrary

public XQueryFunctionLibrary(Configuration config)
Create an XQueryFunctionLibrary

Parameters: config the Saxon configuration

Method Detail

bind

public Expression bind(StructuredQName functionName, Expression[] arguments, StaticContext env)
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.

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.

Returns: a copy of this function library. This must be an instance of the original class.

declareFunction

public void declareFunction(XQueryFunction function)
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)
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

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<XQueryFunction> 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.

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.

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 true 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

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

optimizeGlobalFunctions

protected void optimizeGlobalFunctions()
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