Package com.saxonica.config

Class JavaExtensionLibrary

  • All Implemented Interfaces:
    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.

    • Constructor Detail

      • JavaExtensionLibrary

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

    • Method Detail

      • setExtensionFunctionFactory

        public void setExtensionFunctionFactory​(JavaExtensionFunctionFactory factory)
        Set the ExtensionFunctionFactory to be used by this extension library.
        Parameters:
        factory - This must be an instanceof JavaExtensionFunctionFactory

      • getExtensionFunctionFactory

        public JavaExtensionFunctionFactory getExtensionFunctionFactory()
        Get the ExtensionFunctionFactory used by this extension library.
        Returns:
        the factory, which will always be an instanceof JavaExtensionFunctionFactory

      • isStrictJavaUriFormat

        public boolean isStrictJavaUriFormat()
        Ask whether only the strict "java:" URI format is to be recognized. The default is "true": the value false can be set for backwards compatibility with releases before Saxon 9.2
        Returns:
        true if only the strict format is recognized

      • setStrictJavaUriFormat

        public void setStrictJavaUriFormat​(boolean strict)
        Say that only the strict "java:" URI format is to be recognized. The default is "true": the value false can be set for backwards compatibility with releases before Saxon 9.2
        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

      • 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
        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

      • 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
        Parameters:
        functionName - the qualified name of the function being called
        languageLevel - the XPath language level times 10 (31=XPath 3.1)
        Returns:
        true if a function of this name and arity is available for calling

      • 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)
        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:
        symbolicName - the qualified name and arity 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.
        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
        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 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.

      • 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.

      • getExternalJavaClass

        protected java.lang.Class getExternalJavaClass​(java.lang.String uri,
                                               java.lang.String localName,
                                               boolean debug)
        Get an external Java class corresponding to a given namespace URI, if there is one. The method is protected so it can be overridden in a user-defined subclass.
        Parameters:
        uri - The namespace URI corresponding to the prefix used in the function call.
        localName - The local name of the function, in case this contributes to determining the class
        debug - true if tracing information should be output
        Returns:
        the Java class name if a suitable class exists, otherwise return null.

      • getMethodNameFromLocalName

        protected java.lang.String getMethodNameFromLocalName​(java.lang.String uri,
                                                      java.lang.String localName,
                                                      boolean debug)
        Get the Java method/field name from the local name used in the function call. This may be overridden in a subclass. The default implementation is as follows: if the URI is NamespaceConstant.JAVA_TYPE, the method name is that part of the local name appearing after the last dot/period. Otherwise, it is the local-name, converted to camel-case by removing hyphens and converting any character immediately following a hyphen to upper case.
        Parameters:
        uri - the namespace URI used in the function call
        localName - the local name used in the function call
        debug - true if tracing is requested
        Returns:
        the local name of the method or field

      • 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.