StackManipStmt.java

/* This file is part of the db4o object database http://www.db4o.com

Copyright (C) 2004 - 2011  Versant Corporation http://www.versant.com

db4o is free software; you can redistribute it and/or modify it under
the terms of version 3 of the GNU General Public License as published
by the Free Software Foundation.

db4o 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 General Public License along
with this program.  If not, see http://www.gnu.org/licenses/. */
package EDU.purdue.cs.bloat.tree;

/**
 * StackManipStmt represents the opcodes that manipulate the stack such as
 * <tt>swap</tt> and <tt>dup</tt>.
 */
public class StackManipStmt extends Stmt implements Assign {
	StackExpr[] target;

	StackExpr[] source;

	int kind;

	// 0 1 -> 1 0
	public static final int SWAP = 0;

	// 0 -> 0 0
	public static final int DUP = 1;

	// 0 1 -> 1 0 1
	public static final int DUP_X1 = 2;

	// 0 1 2 -> 2 0 1 2
	public static final int DUP_X2 = 3;

	// 0 1 -> 0 1 0 1
	public static final int DUP2 = 4;

	// 0 1 2 -> 1 2 0 1 2
	public static final int DUP2_X1 = 5;

	// 0 1 2 3 -> 2 3 0 1 2 3
	public static final int DUP2_X2 = 6;

	/**
	 * Constructor.
	 * 
	 * @param target
	 *            The new contents of the stack
	 * @param source
	 *            The old contents of the stack
	 * @param kind
	 *            The kind of stack manipulation (SWAP, DUP, etc.) to take
	 *            place.
	 */
	public StackManipStmt(final StackExpr[] target, final StackExpr[] source,
			final int kind) {
		this.kind = kind;

		this.target = target;

		for (int i = 0; i < target.length; i++) {
			this.target[i].setParent(this);
		}

		this.source = source;

		for (int i = 0; i < source.length; i++) {
			this.source[i].setParent(this);
		}
	}

	public DefExpr[] defs() {
		return target;
	}

	public StackExpr[] target() {
		return target;
	}

	public StackExpr[] source() {
		return source;
	}

	public int kind() {
		return kind;
	}

	public void visit(final TreeVisitor visitor) {
		visitor.visitStackManipStmt(this);
	}

	public void visitForceChildren(final TreeVisitor visitor) {
		if (visitor.reverse()) {
			for (int i = target.length - 1; i >= 0; i--) {
				target[i].visit(visitor);
			}

			for (int i = source.length - 1; i >= 0; i--) {
				source[i].visit(visitor);
			}
		} else {
			for (int i = 0; i < source.length; i++) {
				source[i].visit(visitor);
			}

			for (int i = 0; i < target.length; i++) {
				target[i].visit(visitor);
			}
		}
	}

	public Object clone() {
		final StackExpr[] t = new StackExpr[target.length];

		for (int i = 0; i < target.length; i++) {
			t[i] = (StackExpr) target[i].clone();
		}

		final StackExpr[] s = new StackExpr[source.length];

		for (int i = 0; i < source.length; i++) {
			s[i] = (StackExpr) source[i].clone();
		}

		return copyInto(new StackManipStmt(t, s, kind));
	}
}