/*
 This file is part of the software framework JStatCom, 
 a library for building applications for data based analysis.

 Copyright (C) 2000-2005  Markus Kraetzig

 This library is free software; you can redistribute it and/or modify
 it under the terms of the GNU Lesser General Public License as
 published by the Free Software Foundation; either version 2.1 of the
 License, or (at your option) any later version.

 This library is distributed in the hope that it will be useful, but
 WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 Lesser General Public License for more details.

 You should have received a copy of the GNU Lesser General Public
 License along with this library; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 USA
 */

package com.jstatcom.model;

/**
 * An interface to be implemented by components that provide
 * access to a hierarchy of symbol tables. The implementing class
 * has access to all higher level symbol tables. The local symboltable
 * is only visible to itself and child components that implement
 * SymbolScope.
 * 
 * @author Markus Kraetzig
 */
public interface SymbolScope {

	/**
	 * Gets the top level symbol table.
	 * 
	 * @return symbol table
	 */
	public SymbolTable global();

	/**
	 * Gets the next higher level symbol table.
	 * It should return the the same as local on the parent scope.
	 * If this is already the top level scope, this method
	 * should return the same as global.
	 * 
	 * @return symbol table
	 */
	public SymbolTable upper();

	/**
	 * Gets the local level symbol table that is only visible
	 * to this and all child components that implement SymbolScope.
	 * If this is already the top level scope, this method
	 * should return the same as global.
	 * 
	 * @return symbol table
	 */
	public SymbolTable local();

}