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## 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.
`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.

### 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.

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Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.