Package com.saxonica.ee.extfn.js

Class StubFunctionLibrary

  • All Implemented Interfaces:
    FunctionLibrary
    public class StubFunctionLibrary
extends java.lang.Object
implements FunctionLibrary
    This represents a library of function signatures with no actual implementation in SaxonJ. The function signatures are read from a JSON file. The compiler will accept calls to these functions, and generate these calls in a SEF file, but any attempt to evaluate the function in SaxonJ will fail.

    A specimen file is as follows:

     {
   "namespace": "http://example.com/ns/mocha",
   "signatures": {
     "base64Binary-param": {
       "as": "xs:boolean",
       "param": [
         "xs:base64Binary"
       ],
       "arity": [1]
     },
     "anyAtomicType-param": {
       "as": "xs:boolean",
       "param": [
         "xs:anyAtomicType"
       ],
       "arity": [1]
     }
   }
 }

    The JSON file can also contain a number of such maps, one per namespace, within a containing array.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      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 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.
      FunctionItem 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, int languageLevel)
      Test whether a function with a given name and arity is available
      void loadSignatures​(javax.xml.transform.stream.StreamSource input)
      Load signatures from supplied JSON file.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • StubFunctionLibrary

        public StubFunctionLibrary​(Configuration config)
        Create a stub function library
        Parameters:
        config - the Saxon configuration (always EE)

    • Method Detail

      • loadSignatures

        public void loadSignatures​(javax.xml.transform.stream.StreamSource input)
                    throws XPathException
        Load signatures from supplied JSON file.
        Parameters:
        input - the JSON function signature definitions
        Throws:
        XPathException - if the file is invalid

      • isAvailable

        public boolean isAvailable​(SymbolicName.F functionName,
                           int languageLevel)
        Description copied from interface: FunctionLibrary
        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:
        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
        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

      • 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)
        Description copied from interface: FunctionLibrary
        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:
        functionName - the QName of the function being called
        staticArgs - 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 - 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.
        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.

      • copy

        public FunctionLibrary copy()
        Description copied from interface: FunctionLibrary
        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 functionName,
                                    StaticContext staticContext)
                             throws XPathException
        Description copied from interface: FunctionLibrary
        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:
        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
        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