com.saxonica.config
Class JavaExtensionLibrary

java.lang.Object
  com.saxonica.config.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:

Serialized Form

Constructor Summary

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

Method Summary

protected int	atomicConversionPreference(int primitiveType, Class required) Get the conversion preference from an XPath primitive atomic type to a Java class
Expression	bind(StructuredQName functionName, Expression[] staticArgs, StaticContext env, Container container) 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(String uri, Class theClass) Declare a mapping from a specific namespace URI to a Java class
JavaExtensionFunctionFactory	getExtensionFunctionFactory() Get the ExtensionFunctionFactory used by this extension library.
protected Class	getExternalJavaClass(String uri) Get an external Java class corresponding to a given namespace URI, if there is one.
SequenceType[]	getFunctionSignature(StructuredQName functionName, int arity) Test whether a function with a given name and arity is available; if so, return its signature.
boolean	isStrictJavaUriFormat() Ask whether only the strict "java:" URI format is to be recognized.
void	setExtensionFunctionFactory(JavaExtensionFunctionFactory factory) Set the ExtensionFunctionFactory to be used by this extension library.
void	setStrictJavaUriFormat(boolean strict) Say 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(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(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

getFunctionSignature

public SequenceType[] getFunctionSignature(StructuredQName functionName,
                                           int arity)

Test whether a function with a given name and arity is available; if so, return its signature. This supports the function-available() function in XSLT; it is also used to support higher-order functions introduced in XQuery 1.1.

This method may be called either at compile time or at run time. If the function library is to be used only in an XQuery or free-standing XPath environment, this method may throw an UnsupportedOperationException.

Specified by:

getFunctionSignature in interface FunctionLibrary

Parameters:

functionName - the qualified name of the function being called

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 function of this name available for calling.

Returns:

if a function of this name and arity is available for calling, then the type signature of the function, as an array of sequence types in which the zeroth entry represents the return type; or a zero-length array if the function exists but the signature is not known; or null if the function does not exist

bind

public Expression bind(StructuredQName functionName,
                       Expression[] staticArgs,
                       StaticContext env,
                       Container container)
                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

container -

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.

getExternalJavaClass

protected Class getExternalJavaClass(String uri)

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.

Returns:

the Java class name if a suitable class exists, otherwise return null.

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.