net.sf.saxon.functions
Class ExecutableFunctionLibrary
java.lang.Object
net.sf.saxon.functions.ExecutableFunctionLibrary
- FunctionLibrary, Serializable
public class ExecutableFunctionLibrary
extends java.lang.Object
An ExecutableFunctionLibrary is a function library that contains definitions of functions for use at
run-time. Normally functions are bound at compile-time; however there are various situations in which
the information is needed dynamically, for example (a) to support the XSLT function-available() call
(in the pathological case where the argument is not known statically), (b) to allow functions to be
called from saxon:evaluate(), (c) to allow functions to be called from a debugging breakpoint.
The objects actually held in the ExecutableFunctionLibrary are UserFunctionCall objects that have been
prepared at compile time. These are function calls that do full dynamic type checking: that is, they
are prepared on the basis that the static types of the arguments are all "item()*", meaning that full
type checking is needed at run-time.
void | addFunction(UserFunction fn) - Register a function with the function library
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Expression | bind(StructuredQName functionName, Expression[] staticArgs, StaticContext env) - Bind a function, given the URI and local parts of the function name,
and the list of expressions supplied as arguments.
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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.
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boolean | isAvailable(StructuredQName functionName, int arity) - Test whether a function with a given name and arity is available.
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Iterator | iterateFunctions() - Iterate over all the functions defined in this function library.
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ExecutableFunctionLibrary
public ExecutableFunctionLibrary(Configuration config)
Create the ExecutableFunctionLibrary
config
- the Saxon configuration
addFunction
public void addFunction(UserFunction fn)
Register a function with the function library
fn
- the function to be registered
bind
public Expression bind(StructuredQName functionName,
Expression[] staticArgs,
StaticContext env)
throws XPathException
Bind a 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.
- bind in interface FunctionLibrary
functionName
- The name of the function to be calledstaticArgs
- The expressions supplied statically in 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.env
- the static evaluation context
- An object representing the extension function to be called, if one is found;
null if no extension function was found matching the required name and arity.
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; or if this function library "owns" the namespace containing
the function call, but no function was found.
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.
- copy in interface FunctionLibrary
- a copy of this function library. This must be an instance of the original class.
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.
- isAvailable in interface FunctionLibrary
functionName
- the name of the function being soughtarity
- 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
iterateFunctions
public Iterator iterateFunctions()
Iterate over all the functions defined in this function library. The objects
returned by the iterator are of class
UserFunction
- an iterator delivering the
UserFunction
objects representing
the user-defined functions in a stylesheet or query