public interface FunctionLibrary
FunctionLibraryListthat allows a FunctionLibrary to be constructed by combining other FunctionLibrary objects.
|Modifier and Type||Method and Description|
Bind a function, given the URI and local parts of the function name, and the list of expressions supplied as arguments.
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.
Test whether a function with a given name and arity is available; if so, return a function item that can be dynamically called.
Test whether a function with a given name and arity is available
boolean isAvailable(SymbolicName 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 do
Expression bind(SymbolicName functionName, Expression staticArgs, StaticContext env) throws XPathException
container- The container for the newly created Expression
functionName- the QName of the function being called
staticArgs- 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
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.
Function getFunctionItem(SymbolicName functionName, StaticContext staticContext) throws XPathException
This supports the function-lookup() function in XPath 3.0.
functionName- the qualified name of the function being called
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
XPathException- in the event of certain errors, for example attempting to get a function that is private
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