Class JavaExtensionLibrary

  • All Implemented Interfaces:
    java.io.Serializable, FunctionLibrary

    public class JavaExtensionLibrary
    extends java.lang.Object
    implements FunctionLibrary
    The JavaExtensionLibrary is a FunctionLibrary that binds XPath function calls to calls on Java methods (or constructors, or fields). It performs a mapping from the namespace URI of the function to the Java class (the mapping is partly table driven and partly algorithmic), and maps the local name of the function to the Java method, constructor, or field within the class. If the Java methods are polymorphic, then it tries to select the appropriate method based on the static types of the supplied arguments. Binding is done entirely at XPath compilation time.
    See Also:
    Serialized Form
    • Constructor Summary

      Constructors 
      Constructor Description
      JavaExtensionLibrary​(Configuration config)
      Construct a JavaExtensionLibrary and establish the default uri->class mappings.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      protected int atomicConversionPreference​(int primitiveType, java.lang.Class required)
      Get the conversion preference from an XPath primitive atomic type to a Java class
      Expression bind​(StructuredQName functionName, Expression[] staticArgs, StaticContext env)
      Bind an extension 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.
      void declareJavaClass​(java.lang.String uri, java.lang.Class theClass)
      Declare a mapping from a specific namespace URI to a Java class
      boolean isAvailable​(StructuredQName functionName, int arity)
      Test whether an extension function with a given name and arity is available.
      protected void setDefaultURIMappings()
      Define initial mappings of "well known" namespace URIs to Java classes (this covers the Saxon and EXSLT extensions).
      void setStrictJavaUriFormat​(boolean strict)
      Indicate that only the strict "java:" URI format is to be recognized
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • JavaExtensionLibrary

        public JavaExtensionLibrary​(Configuration config)
        Construct a JavaExtensionLibrary and establish the default uri->class mappings.
        Parameters:
        config - The Saxon configuration
    • Method Detail

      • setDefaultURIMappings

        protected void setDefaultURIMappings()
        Define initial mappings of "well known" namespace URIs to Java classes (this covers the Saxon and EXSLT extensions). The method is protected so it can be overridden in a subclass.
      • setStrictJavaUriFormat

        public void setStrictJavaUriFormat​(boolean strict)
        Indicate that only the strict "java:" URI format is to be recognized
        Parameters:
        strict - true if only the strict format is recognized
      • declareJavaClass

        public void declareJavaClass​(java.lang.String uri,
                                     java.lang.Class theClass)
        Declare a mapping from a specific namespace URI to a Java class
        Parameters:
        uri - the namespace URI of the function name
        theClass - the Java class that implements the functions in this namespace
      • isAvailable

        public boolean isAvailable​(StructuredQName functionName,
                                   int arity)
        Test whether an extension function with a given name and arity is available. This supports the function-available() function in XSLT. This method may be called either at compile time or at run time.
        Specified by:
        isAvailable in interface FunctionLibrary
        Parameters:
        functionName - The qualified name of the extension function
        arity - The number of arguments. This is set to -1 in the case of the single-argument function-available() function; in this case the method should return true if there is some
        Returns:
        true if a function of this name and arity is available for calling.
      • bind

        public Expression bind​(StructuredQName functionName,
                               Expression[] staticArgs,
                               StaticContext env)
                        throws XPathException
        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
        Parameters:
        functionName - the qualified name of the function being called
        staticArgs - The expressions supplied statically in 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.
        env - the static context
        Returns:
        An object representing the extension function to be called, if one is found; null if no extension function was found matching the required name, arity, or signature.
        Throws:
        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.
      • atomicConversionPreference

        protected int atomicConversionPreference​(int primitiveType,
                                                 java.lang.Class required)
        Get the conversion preference from an XPath primitive atomic type to a Java class
        Parameters:
        primitiveType - integer code identifying the XPath primitive type, for example StandardNames.XS_STRING or StandardNames.XS_STRING
        required - The Java Class named in the method signature
        Returns:
        an integer indicating the relative preference for converting this primitive type to this Java class. A high number indicates a low preference. All values are in the range 50 to 100. For example, the conversion of an XPath String to StringValue is 50, while XPath String to String is 51. The value -1 indicates that the conversion is not allowed.
      • 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.