/*

 * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package org.graalvm.compiler.graph;

public final class NodeStack {

    private static final int DEFAULT_INITIAL_SIZE = 8;

    protected Node[] values;

    public int tos;

    public NodeStack() {

        this(DEFAULT_INITIAL_SIZE);

    }

    public NodeStack(int initialSize) {

        values = new Node[initialSize];

    }

    public int size() {

        return tos;

    }

    public void push(Node n) {

        int newIndex = tos++;

        int valuesLength = values.length;

        if (newIndex >= valuesLength) {

            grow();

        }

        values[newIndex] = n;

    }

    private void grow() {

        int valuesLength = values.length;

        Node[] newValues = new Node[valuesLength << 1];

        System.arraycopy(values, 0, newValues, 0, valuesLength);

        values = newValues;

    }

    public Node get(int index) {

        return values[index];

    }

    public Node pop() {

        assert tos > 0 : "stack must be non-empty";

        return values[--tos];

    }

    public Node peek() {

        assert tos > 0 : "stack must be non-empty";

        return values[tos - 1];

    }

    public boolean isEmpty() {

        return tos == 0;

    }

    @Override

    public String toString() {

        if (tos == 0) {

            return "NodeStack: []";

        }

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < tos; i++) {

            sb.append(", ");

            sb.append(values[i]);

        }

        return "NodeStack: [" + sb.substring(2) + "]";

    }

}