Package net.sf.saxon.functions.registry

Class BuiltInFunctionSet

    • Constructor Detail

      • BuiltInFunctionSet

        public BuiltInFunctionSet()

    • Method Detail

      • importFunctionSet

        public final void importFunctionSet​(BuiltInFunctionSet importee)
        Import another function set (which must be in the same namespace)
        Parameters:
        importee - the function set to be imported. (No cycles allowed!)

      • getFunctionDetails

        public BuiltInFunctionSet.Entry getFunctionDetails​(java.lang.String name,
                                                   int arity)
        Locate the entry for a function with a given name and arity, if it exists
        Parameters:
        name - the local part of the function name
        arity - the arity of the function. -1 considers all possibly arities and returns an arbitrary function if one exists with the right name.
        Returns:
        the entry for the required function, or null if not found

      • bind

        public Expression bind​(SymbolicName.F symbolicName,
                       Expression[] staticArgs,
                       java.util.Map<StructuredQName,​java.lang.Integer> keywords,
                       StaticContext env,
                       java.util.List<java.lang.String> reasons)
                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 interface FunctionLibrary
        Parameters:
        symbolicName - the symbolic name 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).

        keywords - Keywords used in keyword parameters, with the 0-based integer position of the argument they are used on.
        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.
        Returns:
        An expression equivalent to a call on the specified function, if one is found; null if no function was found matching the required name and arity.
        Throws:
        XPathException - if a matching function was identified, but the call is incorrect, for example because it uses incorrect argument keywords

      • isAvailable

        public boolean isAvailable​(SymbolicName.F symbolicName,
                           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
        Parameters:
        symbolicName - 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
        languageLevel - the XPath language level (times 10, e.g. 31 for XPath 3.1)
        Returns:
        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
        Returns:
        a copy of this function library. This must be an instance of the original class.

      • getFunctionItem

        public FunctionItem getFunctionItem​(SymbolicName.F symbolicName,
                                    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
        Parameters:
        symbolicName - 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
        Returns:
        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
        Throws:
        XPathException - in the event of certain errors, for example attempting to get a function that is private

      • register

        protected BuiltInFunctionSet.Entry register​(java.lang.String name,
                                            int arity,
                                            java.util.function.Function<BuiltInFunctionSet.Entry,​BuiltInFunctionSet.Entry> populator)
        Register a system function in the table of function details.
        Parameters:
        name - the function name
        arity - the function arity (-1 is treated specially)
        Returns:
        the entry describing the function. The entry is incomplete, it does not yet contain information about the function arguments.

      • getNamespace

        public NamespaceUri getNamespace()
        Return the namespace URI for the functions local to this function set.
        Returns:
        the namespace URI of the functions local to this function set. Note that functions imported from another function set may have a different namespace URI.

      • getConventionalPrefix

        public java.lang.String getConventionalPrefix()
        Return a conventional prefix for use with this namespace, typically the prefix used in the documentation of these functions.
        Returns:
        the string "fn"