/* InstructionContainer 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.expr.Expression;
import net.sf.jode.expr.InvokeOperator;
import net.sf.jode.util.SimpleSet;

///#def COLLECTIONS java.util
import java.util.Set;
///#enddef

/**
 * This is a method for block containing a single instruction.
 */
public abstract class InstructionContainer extends StructuredBlock {
    /**
     * The instruction.
     */
    Expression instr;

    public InstructionContainer(Expression instr) {
        this.instr = instr;
    }

    /**
     * Make the declarations, i.e. initialize the declare variable
     * to correct values.  This will declare every variable that
     * is marked as used, but not done.<br>
     *
     * This will now also combine locals, that use the same slot, have
     * compatible types and are declared in the same block. <br>
     *
     * @param done The set of the already declare variables.
     */
    public void makeDeclaration(Set done) {
	if (instr != null)
	    instr.makeDeclaration(done);
	super.makeDeclaration(done);
    }

    /** 
     * This method should remove local variables that are only written
     * and read one time directly after another.  <br>
     *
     * This is especially important for stack locals, that are created
     * when there are unusual swap or dup instructions, but also makes
     * inlined functions more pretty (but not that close to the
     * bytecode).  
     */
    public void removeOnetimeLocals() {
	if (instr != null)
	    instr = instr.removeOnetimeLocals();
	super.removeOnetimeLocals();
    }

    /**
     * Fill all in variables into the given VariableSet.
     * @param in The VariableSet, the in variables should be stored to.
     */
    public void fillInGenSet(Set in, Set gen) {
	if (instr != null)
	    instr.fillInGenSet(in, gen);
    }

    public Set getDeclarables() {
	Set used = new SimpleSet();
	if (instr != null)
	    instr.fillDeclarables(used);
	return used;
    }

    public boolean doTransformations() {
	if (instr == null)
	    return false;
	/* Do on the fly access$ transformation, since some further
	 * operations need this.
	 */
	if (instr instanceof InvokeOperator) {
	    Expression expr = ((InvokeOperator)instr).simplifyAccess();
	    if (expr != null)
		instr = expr;
	}
        StructuredBlock last = flowBlock.lastModified;
        return CreateNewConstructor.transform(this, last)
            || CreateAssignExpression.transform(this, last)
            || CreateExpression.transform(this, last)
            || CreatePrePostIncExpression.transform(this, last)
            || CreateIfThenElseOperator.create(this, last)
            || CreateConstantArray.transform(this, last)
	    || CreateCheckNull.transformJavac(this, last);
    }

    /**
     * Get the contained instruction.
     * @return the contained instruction.
     */
    public final Expression getInstruction() {
        return instr;
    }

    public void simplify() {
	if (instr != null)
	    instr = instr.simplify();
	super.simplify();
    }

    /**
     * Set the contained instruction.
     * @param instr the new instruction.
     */
    public final void setInstruction(Expression instr) {
        this.instr = instr;
    }
}