Class JavaExtensionLibrary

java.lang.Object
net.sf.saxon.functions.JavaExtensionLibrary
All Implemented Interfaces:
Serializable, FunctionLibrary

public class JavaExtensionLibrary extends 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:
  • Constructor Summary

    Constructors
    Constructor
    Description
    Construct a JavaExtensionLibrary and establish the default uri->class mappings.
  • Method Summary

    Modifier and Type
    Method
    Description
    protected int
    atomicConversionPreference(int primitiveType, Class required)
    Get the conversion preference from an XPath primitive atomic type to a Java class
    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.
    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(String uri, 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
    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 Details

    • JavaExtensionLibrary

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

    • 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(String uri, 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, 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.