/* BreakBlock Copyright (C) 1998-2002 Jochen Hoenicke.
 *
 * This program 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, or (at your option)
 * any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; see the file COPYING.LESSER.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * $Id$
 */

package net.sf.jode.flow;
import net.sf.jode.decompiler.TabbedPrintWriter;

/**
 * 
 */
public class BreakBlock extends StructuredBlock {
    StructuredBlock breaksBlock;
    String label;

    public BreakBlock(BreakableBlock breaksBlock, boolean needsLabel) {
        this.breaksBlock = (StructuredBlock) breaksBlock;
        breaksBlock.setBreaked();
        if (needsLabel) 
            label = breaksBlock.getLabel();
        else
            label = null;
    }

    public void checkConsistent() {
        super.checkConsistent();
        StructuredBlock sb = outer;
        while (sb != breaksBlock) {
            if (sb == null) 
                throw new RuntimeException("Inconsistency");
            sb = sb.outer;
        }
    }

    /**
     * Tells if this block is empty and only changes control flow.
     */
    public boolean isEmpty() {
        return true;
    }

    /**
     * Returns the block where the control will normally flow to, when
     * this block is finished.
     */
    public StructuredBlock getNextBlock() {
        return breaksBlock.getNextBlock();
    }

    /**
     * Returns the flow block where the control will normally flow to,
     * when this block is finished (not ignoring the jump after this
     * block).  
     * @return null, if the control flows into a non empty structured
     * block or if this is the outermost block.
     */
    public FlowBlock getNextFlowBlock() {
        return breaksBlock.getNextFlowBlock();
    }

    /** 
     * This is called after the analysis is completely done.  It
     * will remove all PUSH/stack_i expressions, (if the bytecode
     * is correct).
     * @param stack the stackmap at begin of the block
     * @return null since the stack has no successor.
     */
    public VariableStack mapStackToLocal(VariableStack stack) {
	((BreakableBlock)breaksBlock).mergeBreakedStack(stack);
	return null;
    }

    /**
     * Tells if this block needs braces when used in a if or while block.
     * @return true if this block should be sorrounded by braces.
     */
    public boolean needsBraces() {
        return false;
    }

    public void dumpInstruction(TabbedPrintWriter writer) 
	throws java.io.IOException
    {
        writer.println("break"+(label == null ? "" : " "+label) + ";");
    }

    public boolean jumpMayBeChanged() {
        return true;
    }
}