/* 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: InstructionContainer.java.in,v 4.2.2.1 2002/05/28 17:34:09 hoenicke Exp $
 */

package alterrs.jode.flow;

import java.util.Set;

import alterrs.jode.expr.Expression;
import alterrs.jode.expr.InvokeOperator;
import alterrs.jode.util.SimpleSet;

/**
 * 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;
	}

	public InstructionContainer(Expression instr, Jump jump) {
		this(instr);
		setJump(jump);
	}

	/**
	 * 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>
	 * <p/>
	 * 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>
	 * <p/>
	 * 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;
	}
}
