/**
 * Copyright Verimag laboratory.
 * 
 * contributors:
 *  Anakreontas Mentis
 *  Jacques Combaz (jacques.combaz@univ-grenoble-alpes.fr)
 * 
 * This software is a computer program whose purpose is to generate
 * executable code from BIP models.
 * 
 * This software is governed by the CeCILL-B license under French law and
 * abiding by the rules of distribution of free software.  You can  use, 
 * modify and/ or redistribute the software under the terms of the CeCILL-B
 * license as circulated by CEA, CNRS and INRIA at the following URL
 * "http://www.cecill.info".
 * 
 * As a counterpart to the access to the source code and  rights to copy,
 * modify and redistribute granted by the license, users are provided only
 * with a limited warranty  and the software's author,  the holder of the
 * economic rights,  and the successive licensors  have only  limited
 * liability.
 *
 * In this respect, the user's attention is drawn to the risks associated
 * with loading,  using,  modifying and/or developing or reproducing the
 * software by the user in light of its specific status of free software,
 * that may mean  that it is complicated to manipulate,  and  that  also
 * therefore means  that it is reserved for developers  and  experienced
 * professionals having in-depth computer knowledge. Users are therefore
 * encouraged to load and test the software's suitability as regards their
 * requirements in conditions enabling the security of their systems and/or 
 * data to be ensured and,  more generally, to use and operate it in the 
 * same conditions as regards security.
 * 
 * The fact that you are presently reading this means that you have had
 * knowledge of the CeCILL-B license and that you accept its terms.
 */

package ujf.verimag.bip.middleend.flattening;

import bip2.ujf.verimag.bip.actionlang.*;
import java.util.List;

public class StatementWalker {
	protected ExpressionTreeWalker walker;

	public void setExpressionWalker(ExpressionTreeWalker walker) {
		this.walker = walker;
	}

	protected void checkArgument(Expression ex) {
		if (ex == null) {
			throw new IllegalArgumentException("The provided argument is null!");
		}
	}

	/**
	 * Traverser a list of statements and the expressions contained in
	 * each statement.
	 * @param statements a list of statements
	 */
	public void traverseExpressionList(List<Expression> statements) {
		for (Expression e : statements) {
			traverseExpression(e);
		}
	}		

	/**
	 * Probagates the traversal of an Expression to the method
	 * responsible for handling the specific expression class.
	 * @the value returned by the method handling the concrete
	 * expression type or fails with an assertion error if the
	 * expression type is unknown.
	 */
	public void traverseExpression(Expression ex) {
		checkArgument(ex);
		if (ex instanceof ValuedExpression) {
			walker.traverseValued((ValuedExpression) ex);
		} else if (ex instanceof IfThenElseExpression) {
			traverseIf((IfThenElseExpression) ex);
		} else if (ex instanceof AssignmentExpression) {
			traverseAssignement((AssignmentExpression) ex);
		} else {
			assert(false);
		}
	}

	/**
	 * Applies a transormation on the if condition and statements.
	 * @return null if the condition transormation results to null or
	 * a new if statement with the condition and statements
	 * transormed.
	 */
	public void traverseIf(IfThenElseExpression ife) {
		walker.traverseValued(ife.getCondition());
		traverseExpressionList(ife.getThen());
		traverseExpressionList(ife.getElse());
	}

	/**
	 * Traverser the operands of an assignment statement.
	 */
	public void traverseAssignement(AssignmentExpression aex) {
		walker.traverseValued(aex.getLhs());
		walker.traverseValued(aex.getRhs());
	}
}
