/jEdit/tags/jedit-4-3-pre5/bsh/BlockNameSpace.java

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

/**
    A specialized namespace	for Blocks (e.g. the body of a "for" statement).
	The Block acts like a child namespace but only for typed variables 
	declared within it (block local scope) or untyped variables explicitly set 
	in it via setBlockVariable().  Otherwise variable assignment 
	(including untyped variable usage) acts like it is part of the containing
	block.  
	<p>
*/
/*
	Note: This class essentially just delegates most of its methods to its
	parent.  The setVariable() indirection is very small.  We could probably
	fold this functionality back into the base NameSpace as a special case.
	But this has changed a few times so I'd like to leave this abstraction for
	now.
*/
class BlockNameSpace extends NameSpace 
{
    public BlockNameSpace( NameSpace parent ) 
		throws EvalError
	{
		super( parent, parent.getName()+ "/BlockNameSpace" );
    }

	/**
		Override the standard namespace behavior to make assignments
		happen in our parent (enclosing) namespace, unless the variable has
		already been assigned here via a typed declaration or through
		the special setBlockVariable() (used for untyped args in try/catch).
		<p>
		i.e. only allow typed var declaration to happen in this namespace.
		Typed vars are handled in the ordinary way local scope.  All untyped
		assignments are delegated to the enclosing context.
	*/
	/*
		Note: it may see like with the new 1.3 scoping this test could be
		removed, but it cannot.  When recurse is false we still need to set the
		variable in our parent, not here.
	*/
    public void	setVariable( 
		String name, Object value, boolean strictJava, boolean recurse ) 
		throws UtilEvalError 
	{
		if ( weHaveVar( name ) ) 
			// set the var here in the block namespace
			super.setVariable( name, value, strictJava, false );
		else
			// set the var in the enclosing (parent) namespace
			getParent().setVariable( name, value, strictJava, recurse );
    }

	/**
		Set an untyped variable in the block namespace.
		The BlockNameSpace would normally delegate this set to the parent.
		Typed variables are naturally set locally.
		This is used in try/catch block argument. 
	*/
    public void	setBlockVariable( String name, Object value ) 
		throws UtilEvalError 
	{
		super.setVariable( name, value, false/*strict?*/, false );
	}

	/**
		We have the variable: either it was declared here with a type, giving
		it block local scope or an untyped var was explicitly set here via
		setBlockVariable().
	*/
	private boolean weHaveVar( String name ) 
	{
		// super.variables.containsKey( name ) not any faster, I checked
		try {
			return super.getVariableImpl( name, false ) != null;
		} catch ( UtilEvalError e ) { return false; }
	}

/**
		Get the actual BlockNameSpace 'this' reference.
		<p/>
		Normally a 'this' reference to a BlockNameSpace (e.g. if () { } )
		resolves to the parent namespace (e.g. the namespace containing the
		"if" statement).  However when code inside the BlockNameSpace needs to
		resolve things relative to 'this' we must use the actual block's 'this'
		reference.  Name.java is smart enough to handle this using
		getBlockThis().
		@see #getThis( Interpreter )
    This getBlockThis( Interpreter declaringInterpreter ) 
	{
		return super.getThis( declaringInterpreter );
	}
*/

	//
	// Begin methods which simply delegate to our parent (enclosing scope) 
	//

	/**
		This method recurses to find the nearest non-BlockNameSpace parent.

	public NameSpace getParent() 
	{
		NameSpace parent = super.getParent();
		if ( parent instanceof BlockNameSpace )
			return parent.getParent();
		else
			return parent;
	}
*/
	/** do we need this? */
	private NameSpace getNonBlockParent() 
	{
		NameSpace parent = super.getParent();
		if ( parent instanceof BlockNameSpace )
			return ((BlockNameSpace)parent).getNonBlockParent();
		else
			return parent;
	}

	/**
		Get a 'this' reference is our parent's 'this' for the object closure.
		e.g. Normally a 'this' reference to a BlockNameSpace (e.g. if () { } )
		resolves to the parent namespace (e.g. the namespace containing the
		"if" statement). 
		@see #getBlockThis( Interpreter )
	*/
    This getThis( Interpreter declaringInterpreter ) {
		return getNonBlockParent().getThis( declaringInterpreter );
	}

	/**
		super is our parent's super
	*/
    public This getSuper( Interpreter declaringInterpreter ) {
		return getNonBlockParent().getSuper( declaringInterpreter );
	}

	/**
		delegate import to our parent
	*/
    public void	importClass(String name) {
		getParent().importClass( name );
	}

	/**
		delegate import to our parent
	*/
    public void	importPackage(String name) {
		getParent().importPackage( name );
	}

    public void	setMethod(String name, BshMethod method) 
		throws UtilEvalError
	{
		getParent().setMethod( name, method );
	}
}