Class IntegratedFunctionLibrary

  • All Implemented Interfaces:

    public class IntegratedFunctionLibrary
    extends java.lang.Object
    implements FunctionLibrary
    A library of integrated function calls, that is, user-written extension functions implemented as instances of the class ExtensionFunctionDefinition.
    • Constructor Detail

      • IntegratedFunctionLibrary

        public IntegratedFunctionLibrary()
    • Method Detail

      • registerFunction

        public void registerFunction​(ExtensionFunctionDefinition function)
        Register an integrated function with this function library
        function - the implementation of the function (or set of functions)
      • bind

        public Expression bind​(SymbolicName.F functionName,
                               Expression[] staticArgs,
                               java.util.Map<StructuredQName,​java.lang.Integer> keywords,
                               StaticContext env,
                               java.util.List<java.lang.String> reasons)
        Bind an extension 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 interface FunctionLibrary
        functionName - the QName and arity of the function being called
        staticArgs - The expressions supplied statically in arguments to the function call. The length of this array represents the arity of the function. 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).

        keywords - May be null if no keywords are used in the function call. Otherwise, a map identifying the keywords appearing in the function call, and the 0-based position at which they appeared.
        env - The static context of the function call
        reasons - If no matching function is found by the function library, it may add a diagnostic explanation to this list explaining why none of the available functions could be used.
        An object representing the function to be called, if one is found; null if no function was found matching the required name and arity.
      • getFunctionItem

        public FunctionItem getFunctionItem​(SymbolicName.F functionName,
                                            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
        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
        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
        XPathException - in the event of certain errors, for example attempting to get a function that is private
      • isAvailable

        public boolean isAvailable​(SymbolicName.F functionName,
                                   int languageLevel)
        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
        functionName - the qualified name of the function being called
        languageLevel - the XPath language level, times 10 (31 = XPath 3.1)
        true if a function of this name and arity is available for calling
      • 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
        a copy of this function library. This must be an instance of the original class.