/*****************************************************************************
 *                                                                           *
 *  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;

class BSHBlock extends SimpleNode
{
	public boolean isSynchronized = false;

	BSHBlock(int id) { super(id); }

	public Object eval( CallStack callstack, Interpreter interpreter) 
		throws EvalError
	{
		return eval( callstack, interpreter, false );
	}

	/**
		@param overrideNamespace if set to true the block will be executed
		in the current namespace (not a subordinate one).
		<p>
		If true *no* new BlockNamespace will be swapped onto the stack and 
		the eval will happen in the current
		top namespace.  This is used by BshMethod, TryStatement, etc.  
		which must intialize the block first and also for those that perform 
		multiple passes in the same block.
	*/
	public Object eval( 
		CallStack callstack, Interpreter interpreter, 
		boolean overrideNamespace ) 
		throws EvalError
	{
		Object syncValue = null;
		if ( isSynchronized ) 
		{
			// First node is the expression on which to sync
			SimpleNode exp = ((SimpleNode)jjtGetChild(0));
			syncValue = exp.eval(callstack, interpreter);
		}

		Object ret;
		if ( isSynchronized ) // Do the actual synchronization
			synchronized( syncValue )
			{
				ret = evalBlock( 
					callstack, interpreter, overrideNamespace, null/*filter*/);
			}
		else
				ret = evalBlock( 
					callstack, interpreter, overrideNamespace, null/*filter*/ );

		return ret;
	}

	Object evalBlock( 
		CallStack callstack, Interpreter interpreter, 
		boolean overrideNamespace, NodeFilter nodeFilter ) 
		throws EvalError
	{	
		Object ret = Primitive.VOID;
		NameSpace enclosingNameSpace = null;
		if ( !overrideNamespace ) 
		{
			enclosingNameSpace= callstack.top();
			BlockNameSpace bodyNameSpace = 
				new BlockNameSpace( enclosingNameSpace );

			callstack.swap( bodyNameSpace );
		}

		int startChild = isSynchronized ? 1 : 0;
		int numChildren = jjtGetNumChildren();

		try {
			/*
				Evaluate block in two passes: 
				First do class declarations then do everything else.
			*/
			for(int i=startChild; i<numChildren; i++)
			{
				SimpleNode node = ((SimpleNode)jjtGetChild(i));

				if ( nodeFilter != null && !nodeFilter.isVisible( node ) )
					continue;

				if ( node instanceof BSHClassDeclaration )
					node.eval( callstack, interpreter );
			}
			for(int i=startChild; i<numChildren; i++)
			{
				SimpleNode node = ((SimpleNode)jjtGetChild(i));
				if ( node instanceof BSHClassDeclaration )
					continue;

				// filter nodes
				if ( nodeFilter != null && !nodeFilter.isVisible( node ) )
					continue;

				ret = node.eval( callstack, interpreter );

				// statement or embedded block evaluated a return statement
				if ( ret instanceof ReturnControl )
					break;
			}
		} finally {
			// make sure we put the namespace back when we leave.
			if ( !overrideNamespace ) 
				callstack.swap( enclosingNameSpace );
		}
		return ret;
	}

	public interface NodeFilter {
		public boolean isVisible( SimpleNode node );
	}

}

