/*
 * Copyright (c) 2009, IETR/INSA of Rennes
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *   * Neither the name of the IETR/INSA of Rennes nor the names of its
 *     contributors may be used to endorse or promote products derived from this
 *     software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
package net.sf.orcc.ir.transform;

import net.sf.orcc.ir.BlockBasic;
import net.sf.orcc.ir.BlockIf;
import net.sf.orcc.ir.BlockWhile;
import net.sf.orcc.ir.Procedure;
import net.sf.orcc.ir.util.AbstractIrVisitor;
import net.sf.orcc.util.Void;

import org.eclipse.emf.ecore.util.EcoreUtil;

/**
 * This class defines an actor transformation that combines blocks of
 * instructions together.
 * 
 * @author Matthieu Wipliez
 * 
 */
public class BlockCombine extends AbstractIrVisitor<Void> {

	private BlockBasic previous;

	private final Boolean combineJoinBlock;

	public BlockCombine() {
		combineJoinBlock = true;
	}

	public BlockCombine(Boolean combineJoinBlock) {
		this.combineJoinBlock = combineJoinBlock;
	}

	@Override
	public Void caseBlockBasic(BlockBasic block) {
		if (previous == null) {
			previous = block;
		} else {
			// add instructions of this block after previous block's
			// instructions
			previous.getInstructions().addAll(block.getInstructions());

			// remove this block
			EcoreUtil.remove(block);
			indexBlock--;
		}

		return null;
	}

	@Override
	public Void caseBlockIf(BlockIf block) {
		// so that previous blocks are not linked to then branch
		previous = null;
		doSwitch(block.getThenBlocks());

		// so that previous blocks are not linked to else branch
		previous = null;
		doSwitch(block.getElseBlocks());

		// so that neither then nor else branch are linked to this join
		// as a matter of fact, this also ensures correctness in nested ifs
		// if combineJoinBlock is true
		previous = null;
		if (combineJoinBlock) {
			doSwitch(block.getJoinBlock());
		}

		// we do not set previous to null again, because join may be combined
		// with next blocks (actually it needs to be).

		return null;
	}

	@Override
	public Void caseBlockWhile(BlockWhile block) {
		// previous blocks are not linked to the body of the while
		previous = null;
		doSwitch(block.getBlocks());

		// no previous block to be linked to
		previous = null;

		return null;
	}

	@Override
	public Void caseProcedure(Procedure procedure) {
		previous = null;
		return super.caseProcedure(procedure);
	}

}