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OpenL Constraint Programming engine

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///////////////////////////////////////////////////////////////////////////////
/*
 * Copyright Exigen Group 1998, 1999, 2000
 * 320 Amboy Ave., Metuchen, NJ, 08840, USA, www.exigengroup.com
 *
 * The copyright to the computer program(s) herein
 * is the property of Exigen Group, USA. All rights reserved.
 * The program(s) may be used and/or copied only with
 * the written permission of Exigen Group
 * or in accordance with the terms and conditions
 * stipulated in the agreement/contract under which
 * the program(s) have been supplied.
 */
///////////////////////////////////////////////////////////////////////////////
package org.openl.ie.tools;

// "implements serializable"  was added by Eugeny Tseitlin 18.06.2003
public final class FastStack implements Cloneable, java.io.Serializable {

    static final int DEFAULT_CAPACITY = 10;

    Object[] m_data;
    int m_size;

    public FastStack() {
        this(DEFAULT_CAPACITY);
    }

    public FastStack(int capacity) {
        m_size = 0;
        if (capacity == 0) {
            capacity = DEFAULT_CAPACITY;
        }
        m_data = new Object[capacity];
    }

    public void clear() {
        m_size = 0;
        m_data = new Object[m_data.length];
    }

    @Override
    public Object clone() {
        try {
            FastStack v = (FastStack) super.clone();
            v.m_data = m_data.clone();
            return v;
        } catch (CloneNotSupportedException e) {
            // this shouldn't happen, since we are Cloneable
            throw new InternalError();
        }
    }

    public boolean empty() {
        return m_size == 0;
    }

    void grow() {
        Object[] old = m_data;

        m_data = new Object[m_data.length * 2];
        System.arraycopy(old, 0, m_data, 0, m_size);
    }

    public Object peek() {
        return m_data[m_size - 1];
    }

    public Object pop() {
        Object o = m_data[--m_size];
        m_data[m_size] = null;
        return o;
    }

    public void push(Object obj) {
        if (m_size == m_data.length) {
            grow();
        }

        m_data[m_size++] = obj;
    }

    public void setSize(int newSize) {
        while (m_size > newSize) {
            m_data[--m_size] = null;
        }
    }

    public int size() {
        return m_size;
    }

}