/jEdit/tags/jedit-4-2-pre4/bsh/XThis.java
Java | 199 lines | 86 code | 22 blank | 91 comment | 14 complexity | 55e681c2e1a3505053b80a3fca4397fe MD5 | raw file
Possible License(s): BSD-3-Clause, AGPL-1.0, Apache-2.0, LGPL-2.0, LGPL-3.0, GPL-2.0, CC-BY-SA-3.0, LGPL-2.1, GPL-3.0, MPL-2.0-no-copyleft-exception, IPL-1.0
- /*****************************************************************************
- * *
- * This file is part of the BeanShell Java Scripting distribution. *
- * Documentation and updates may be found at http://www.beanshell.org/ *
- * *
- * Sun Public License Notice: *
- * *
- * The contents of this file are subject to the Sun Public License Version *
- * 1.0 (the "License"); you may not use this file except in compliance with *
- * the License. A copy of the License is available at http://www.sun.com *
- * *
- * The Original Code is BeanShell. The Initial Developer of the Original *
- * Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright *
- * (C) 2000. All Rights Reserved. *
- * *
- * GNU Public License Notice: *
- * *
- * Alternatively, the contents of this file may be used under the terms of *
- * the GNU Lesser General Public License (the "LGPL"), in which case the *
- * provisions of LGPL are applicable instead of those above. If you wish to *
- * allow use of your version of this file only under the terms of the LGPL *
- * and not to allow others to use your version of this file under the SPL, *
- * indicate your decision by deleting the provisions above and replace *
- * them with the notice and other provisions required by the LGPL. If you *
- * do not delete the provisions above, a recipient may use your version of *
- * this file under either the SPL or the LGPL. *
- * *
- * Patrick Niemeyer (pat@pat.net) *
- * Author of Learning Java, O'Reilly & Associates *
- * http://www.pat.net/~pat/ *
- * *
- *****************************************************************************/
- package bsh;
- import java.lang.reflect.*;
- import java.lang.reflect.InvocationHandler;
- import java.io.*;
- import java.util.Hashtable;
- /**
- XThis is a dynamically loaded extension which extends This.java and adds
- support for the generalized interface proxy mechanism introduced in
- JDK1.3. XThis allows bsh scripted objects to implement arbitrary
- interfaces (be arbitrary event listener types).
- Note: This module relies on new features of JDK1.3 and will not compile
- with JDK1.2 or lower. For those environments simply do not compile this
- class.
- Eventually XThis should become simply This, but for backward compatability
- we will maintain This without requiring support for the proxy mechanism.
- XThis stands for "eXtended This" (I had to call it something).
-
- @see JThis See also JThis with explicit JFC support for compatability.
- @see This
- */
- class XThis extends This
- {
- /**
- A cache of proxy interface handlers.
- Currently just one per interface.
- */
- Hashtable interfaces;
- InvocationHandler invocationHandler = new Handler();
- XThis( NameSpace namespace, Interpreter declaringInterp ) {
- super( namespace, declaringInterp );
- }
- public String toString() {
- return "'this' reference (XThis) to Bsh object: " + namespace;
- }
- /**
- Get dynamic proxy for interface, caching those it creates.
- */
- public Object getInterface( Class clas )
- {
- return getInterface( new Class[] { clas } );
- }
- /**
- Get dynamic proxy for interface, caching those it creates.
- */
- public Object getInterface( Class [] ca )
- {
- if ( interfaces == null )
- interfaces = new Hashtable();
- // Make a hash of the interface hashcodes in order to cache them
- int hash = 21;
- for(int i=0; i<ca.length; i++)
- hash *= ca[i].hashCode() + 3;
- Object hashKey = new Integer(hash);
- Object interf = interfaces.get( hashKey );
- if ( interf == null )
- {
- ClassLoader classLoader = ca[0].getClassLoader(); // ?
- interf = Proxy.newProxyInstance(
- classLoader, ca, invocationHandler );
- interfaces.put( hashKey, interf );
- }
- return interf;
- }
- /**
- This is the invocation handler for the dynamic proxy.
- <p>
- Notes:
- Inner class for the invocation handler seems to shield this unavailable
- interface from JDK1.2 VM...
-
- I don't understand this. JThis works just fine even if those
- classes aren't there (doesn't it?) This class shouldn't be loaded
- if an XThis isn't instantiated in NameSpace.java, should it?
- */
- class Handler implements InvocationHandler, java.io.Serializable
- {
- public Object invoke( Object proxy, Method method, Object[] args )
- throws Throwable
- {
- try {
- return invokeImpl( proxy, method, args );
- } catch ( TargetError te ) {
- // Unwrap target exception. If the interface declares that
- // it throws the ex it will be delivered. If not it will be
- // wrapped in an UndeclaredThrowable
- throw te.getTarget();
- } catch ( EvalError ee ) {
- // Ease debugging...
- // XThis.this refers to the enclosing class instance
- if ( Interpreter.DEBUG )
- Interpreter.debug( "EvalError in scripted interface: "
- + XThis.this.toString() + ": "+ ee );
- throw ee;
- }
- }
- public Object invokeImpl( Object proxy, Method method, Object[] args )
- throws EvalError
- {
- String methodName = method.getName();
- CallStack callstack = new CallStack( namespace );
- /*
- If equals() is not explicitly defined we must override the
- default implemented by the This object protocol for scripted
- object. To support XThis equals() must test for equality with
- the generated proxy object, not the scripted bsh This object;
- otherwise callers from outside in Java will not see a the
- proxy object as equal to itself.
- */
- BshMethod equalsMethod = null;
- try {
- equalsMethod = namespace.getMethod(
- "equals", new Class [] { Object.class } );
- } catch ( UtilEvalError e ) {/*leave null*/ }
- if ( methodName.equals("equals" ) && equalsMethod == null ) {
- Object obj = args[0];
- return new Boolean( proxy == obj );
- }
- /*
- If toString() is not explicitly defined override the default
- to show the proxy interfaces.
- */
- BshMethod toStringMethod = null;
- try {
- toStringMethod =
- namespace.getMethod( "toString", new Class [] { } );
- } catch ( UtilEvalError e ) {/*leave null*/ }
- if ( methodName.equals("toString" ) && toStringMethod == null)
- {
- Class [] ints = proxy.getClass().getInterfaces();
- // XThis.this refers to the enclosing class instance
- StringBuffer sb = new StringBuffer(
- XThis.this.toString() + "\nimplements:" );
- for(int i=0; i<ints.length; i++)
- sb.append( " "+ ints[i].getName()
- + ((ints.length > 1)?",":"") );
- return sb.toString();
- }
- return Primitive.unwrap( invokeMethod( methodName, args ) );
- }
- };
- }