001/*
002 * Copyright (c) 2015, 2015, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package com.oracle.graal.graph;
024
025public class NodeStack {
026
027    private static final int INITIAL_SIZE = 8;
028
029    protected Node[] values;
030    protected int tos;
031
032    public NodeStack() {
033        values = new Node[INITIAL_SIZE];
034    }
035
036    public void push(Node n) {
037        int newIndex = tos++;
038        int valuesLength = values.length;
039        if (newIndex >= valuesLength) {
040            Node[] newValues = new Node[valuesLength << 1];
041            System.arraycopy(values, 0, newValues, 0, valuesLength);
042            values = newValues;
043        }
044        values[newIndex] = n;
045    }
046
047    public Node pop() {
048        assert tos > 0 : "stack must be non-empty";
049        return values[--tos];
050    }
051
052    public Node peek() {
053        assert tos > 0 : "stack must be non-empty";
054        return values[tos - 1];
055    }
056
057    public boolean isEmpty() {
058        return tos == 0;
059    }
060}