Package net.sf.saxon.functions
Class ExecutableFunctionLibrary
java.lang.Object
net.sf.saxon.functions.ExecutableFunctionLibrary
- All Implemented Interfaces:
Serializable
,FunctionLibrary
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.
- See Also:
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Constructor Summary
ConstructorsConstructorDescriptionCreate the ExecutableFunctionLibrary -
Method Summary
Modifier and TypeMethodDescriptionvoid
Register a function with the function librarybind
(StructuredQName functionName, Expression[] staticArgs, StaticContext env, Container container) Bind a function, given the URI and local parts of the function name, and the list of expressions supplied as arguments.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.getFunctionSignature
(StructuredQName functionName, int arity) Test whether a function with a given name and arity is available; if so, return its signature.Iterate over all the functions defined in this function library.
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Constructor Details
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ExecutableFunctionLibrary
Create the ExecutableFunctionLibrary- Parameters:
config
- the Saxon configuration
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Method Details
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addFunction
Register a function with the function library- Parameters:
fn
- the function to be registered
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getFunctionSignature
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.
- Specified by:
getFunctionSignature
in interfaceFunctionLibrary
- Parameters:
functionName
- the qualified name of the function being calledarity
- 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
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bind
public Expression bind(StructuredQName functionName, Expression[] staticArgs, StaticContext env, Container container) 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.- Specified by:
bind
in interfaceFunctionLibrary
- Parameters:
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 contextcontainer
-- Returns:
- 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.
- 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; or if this function library "owns" the namespace containing the function call, but no function was found.
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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 interfaceFunctionLibrary
- Returns:
- a copy of this function library. This must be an instance of the original class.
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iterateFunctions
Iterate over all the functions defined in this function library. The objects returned by the iterator are of classUserFunction
- Returns:
- an iterator delivering the
UserFunction
objects representing the user-defined functions in a stylesheet or query
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