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 *                                                                           *
 *  This file is part of the BeanShell Java Scripting distribution.          *
 *  Documentation and updates may be found at      *
 *                                                                           *
 *  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    * 
 *                                                                           *
 *  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 (                                           *
 *  Author of Learning Java, O'Reilly & Associates                           *
 *                                                 *
 *                                                                           *

package bsh;


	'This' is the type of bsh scripted objects.
	A 'This' object is a bsh scripted object context.  It holds a namespace 
	reference and implements event listeners and various other interfaces.

	This holds a reference to the declaring interpreter for callbacks from
	outside of bsh.
public class This implements, Runnable 
		The namespace that this This reference wraps.
	NameSpace namespace;

		This is the interpreter running when the This ref was created.
		It's used as a default interpreter for callback through the This
		where there is no current interpreter instance 
		e.g. interface proxy or event call backs from outside of bsh.
	transient Interpreter declaringInterpreter;

		getThis() is a factory for bsh.This type references.  The capabilities
		of ".this" references in bsh are version dependent up until jdk1.3.
		The version dependence was to support different default interface
		implementations.  i.e. different sets of listener interfaces which
		scripted objects were capable of implementing.  In jdk1.3 the 
		reflection proxy mechanism was introduced which allowed us to 
		implement arbitrary interfaces.  This is fantastic.

		A This object is a thin layer over a namespace, comprising a bsh object
		context.  We create it here only if needed for the namespace.

		Note: this method could be considered slow because of the way it 
		dynamically factories objects.  However I've also done tests where 
		I hard-code the factory to return JThis and see no change in the 
		rough test suite time.  This references are also cached in NameSpace.  
    static This getThis( 
		NameSpace namespace, Interpreter declaringInterpreter ) 
		try {
			Class c;
			if ( Capabilities.canGenerateInterfaces() )
				c = Class.forName( "bsh.XThis" );
			else if ( Capabilities.haveSwing() )
				c = Class.forName( "bsh.JThis" );
				return new This( namespace, declaringInterpreter );

			return (This)Reflect.constructObject( c,
				new Object [] { namespace, declaringInterpreter } );

		} catch ( Exception e ) {
			throw new InterpreterError("internal error 1 in This: "+e);

		Get a version of this scripted object implementing the specified 
		If this type of This implements it directly return this,
		else try complain that we don't have the proxy mechanism.
	public Object getInterface( Class clas ) 
		throws UtilEvalError
		if ( clas.isInstance( this ) )
			return this;
			throw new UtilEvalError( "Dynamic proxy mechanism not available. "
			+ "Cannot construct interface type: "+clas );

		Get a version of this scripted object implementing the specified
	public Object getInterface( Class [] ca ) 
		throws UtilEvalError
		for(int i=0; i

		Note: If you use this method outside of the bsh package and wish to 
		use variables with primitive values you will have to wrap them using 
		bsh.Primitive.  Consider using This getInterface() to make a true Java
		interface for invoking your scripted methods.

This method also implements the default object protocol of toString(), hashCode() and equals() and the invoke() meta-method handling as a last resort.

Note: The invoke() meta-method will not catch the Object protocol methods (toString(), hashCode()...). If you want to override them you have to script them directly.

@see bsh.This.invokeMethod( String methodName, Object [] args, Interpreter interpreter, CallStack callstack, SimpleNode callerInfo ) @param if callStack is null a new CallStack will be created and initialized with this namespace. @param declaredOnly if true then only methods declared directly in the namespace will be visible - no inherited or imported methods will be visible. @see bsh.Primitive */ /* invokeMethod() here is generally used by outside code to callback into the bsh interpreter. e.g. when we are acting as an interface for a scripted listener, etc. In this case there is no real call stack so we make a default one starting with the special JAVACODE namespace and our namespace as the next. */ public Object invokeMethod( String methodName, Object [] args, Interpreter interpreter, CallStack callstack, SimpleNode callerInfo, boolean declaredOnly ) throws EvalError { /* Wrap nulls. This is a bit of a cludge to address a deficiency in the class generator whereby it does not wrap nulls on method delegate. See Class If we fix that then we can remove this. (just have to generate the code there.) */ if ( args != null ) { Object [] oa = new Object [args.length]; for(int i=0; i This is a static utility method because it's used by a bsh command bind() and the interpreter doesn't currently allow access to direct methods of This objects (small hack) */ public static void bind( This ths, NameSpace namespace, Interpreter declaringInterpreter ) { ths.namespace.setParent( namespace ); ths.declaringInterpreter = declaringInterpreter; } /** Allow invocations of these method names on This type objects. Don't give bsh.This a chance to override their behavior.

If the method is passed here the invocation will actually happen on the bsh.This object via the regular reflective method invocation mechanism. If not, then the method is evaluated by bsh.This itself as a scripted method call. */ static boolean isExposedThisMethod( String name ) { return name.equals("getClass") || name.equals("invokeMethod") || name.equals("getInterface") // These are necessary to let us test synchronization from scripts || name.equals("wait") || name.equals("notify") || name.equals("notifyAll"); } }

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