public interface FunctionLibrary
FunctionLibraryList
that allows a FunctionLibrary
to be constructed by combining other FunctionLibrary objects.Modifier and Type | Method and Description |
---|---|
Expression |
bind(SymbolicName.F 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.
|
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.
|
Function |
getFunctionItem(SymbolicName.F functionName,
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.
|
boolean |
isAvailable(SymbolicName.F functionName)
Test whether a function with a given name and arity is available
|
boolean isAvailable(SymbolicName.F functionName)
This supports the function-available() function in XSLT.
functionName
- the qualified name of the function being called, together with its arity.
For legacy reasons, the arity may be set to -1 to mean any arity will doExpression bind(SymbolicName.F functionName, Expression[] staticArgs, StaticContext env) throws XPathException
functionName
- the QName of the function being calledstaticArgs
- 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 callXPathException
- 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.FunctionLibrary copy()
Function getFunctionItem(SymbolicName.F functionName, StaticContext staticContext) throws XPathException
This supports the function-lookup() function in XPath 3.0.
functionName
- the qualified name of the function being calledstaticContext
- the static context to be used by the function, in the event that
it is a system function with dependencies on the static contextXPathException
- in the event of certain errors, for example attempting to get a function
that is privateCopyright (c) 2004-2018 Saxonica Limited. All rights reserved.