net.sf.saxon.functions

Class JavaExtensionLibrary

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.
Constructor Summary
JavaExtensionLibrary(Configuration config)
Construct a JavaExtensionLibrary and establish the default uri->class mappings.
Method Summary
protected intatomicConversionPreference(int primitiveType, Class required)
Get the conversion preference from an XPath primitive atomic type to a Java class
Expressionbind(int nameCode, String uri, String local, Expression[] staticArgs)
Bind an extension function, given the URI and local parts of the function name, and the list of expressions supplied as arguments.
FunctionLibrarycopy()
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.
voiddeclareJavaClass(String uri, Class theClass)
Declare a mapping from a specific namespace URI to a Java class
booleanisAvailable(int fingerprint, String uri, String local, int arity)
Test whether an extension function with a given name and arity is available.
protected voidsetDefaultURIMappings()
Define initial mappings of "well known" namespace URIs to Java classes (this covers the Saxon and EXSLT extensions).

Constructor Detail

JavaExtensionLibrary

public JavaExtensionLibrary(Configuration config)
Construct a JavaExtensionLibrary and establish the default uri->class mappings.

Parameters: config The Saxon configuration

Method Detail

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 INTEGER or 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 java.lang.String is 51. The value -1 indicates that the conversion is not allowed.

bind

public Expression bind(int nameCode, String uri, String local, Expression[] staticArgs)
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.

Parameters: nameCode The namepool code of the function name. This must match the supplied URI and local name. uri The URI of the function name local The local part of the function name 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.

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.

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.

Returns: a copy of this function library. This must be an instance of the original class.

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(int fingerprint, String uri, String local, 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.

Parameters: fingerprint The code that identifies the function name in the NamePool. This must match the supplied URI and local name. uri The URI of the function name local The local part of the function name 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 matching extension function, regardless of its arity.

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.