net.sf.saxon.query

Class XQueryFunctionLibrary

java.lang.Object

net.sf.saxon.query.XQueryFunctionLibrary

All Implemented Interfaces:

Serializable, FunctionLibrary, XQueryFunctionBinder

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.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	XQueryFunctionLibrary.UnresolvedCallable Inner class containing information about a reference to a function whose declaration has not yet been encountered.

Constructor Summary

Constructors

Constructor and Description
XQueryFunctionLibrary(Configuration config) Create an XQueryFunctionLibrary

Method Summary

Methods

Modifier and Type	Method and Description
Expression	bind(StructuredQName functionName, int arity, Expression[] arguments, StaticContext env, Container container) 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<XQueryFunction>	getFunctionDefinitions() Get an iterator over the Functions defined in this module
FunctionItem	getFunctionItem(StructuredQName functionName, int arity, StaticContext staticContext) Test whether a function with a given name and arity is available; if so, return a function item that can be dynamically called.
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

Methods inherited from class java.lang.Object

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

Constructor Detail

XQueryFunctionLibrary

public XQueryFunctionLibrary(Configuration config)

Create an XQueryFunctionLibrary

Parameters:

config - the Saxon configuration

Method Detail

setConfiguration

public void setConfiguration(Configuration config)

Set the Configuration options

Parameters:

config - the Saxon configuration

getConfiguration

public Configuration getConfiguration()

Get the Configuration options

Returns:

the Saxon configuration

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

getFunctionItem

public FunctionItem getFunctionItem(StructuredQName functionName,
                           int arity,
                           StaticContext staticContext)
                             throws XPathException

Test whether a function with a given name and arity is available; if so, return a function item that can be dynamically called.

This supports the function-lookup() function in XPath 3.0.

Specified by:

getFunctionItem in interface FunctionLibrary

Parameters:

functionName - the qualified name of the function being called

arity - The number of arguments.

staticContext - the static context to be used by the function, in the event that it is a system function with dependencies on the static context

Returns:

if a function of this name and arity is available for calling, then a corresponding function item; or null if the function does not exist

Throws:

XPathException - in the event of certain errors, for example attempting to get a function that is private

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.

Specified by:

isAvailable in interface FunctionLibrary

Parameters:

functionName - the qualified name of the function being called

arity - The number of arguments.

Returns:

true if a function of this name and arity is available for calling

bind

public Expression bind(StructuredQName functionName,
              int arity,
              Expression[] arguments,
              StaticContext env,
              Container container)
                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

Parameters:

functionName - the QName of the function being called

arity - The number of arguments supplied in the function call

arguments - May be null; if present, the length of the array must match the value of arity. Contains the expressions supplied statically in arguments to 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. 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 - The static context of the function call

container - The container for the newly created Expression

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.

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.

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.

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.

Throws:

XPathException - if an error occurs

optimizeGlobalFunctions

protected void optimizeGlobalFunctions()
                                throws XPathException

Optimize the body of all global functions. This may involve inlining functions calls

Throws:

XPathException - if an error occurs

explainGlobalFunctions

public void explainGlobalFunctions(ExpressionPresenter out)

Output "explain" information about each declared function

Parameters:

out - the ExpressionPresenter that renders the output

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

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.