/**
*******************************************************************************
* Copyright (C) 1996-2001, International Business Machines Corporation and    *
* others. All Rights Reserved.                                                *
*******************************************************************************
*
* $Source: /xsrl/Nsvn/icu/unicodetools/com/ibm/text/utility/IntStack.java,v $
* $Date: 2001/09/19 23:33:52 $
* $Revision: 1.3 $
*
*******************************************************************************
*/

package com.ibm.text.utility;

// =============================================================
// Simple stack mechanism, with push, pop and access
// =============================================================

public final class IntStack implements Comparable {
    private int[] values;
    private int top = 0;

    public IntStack(int initialSize) {
        values = new int[initialSize];
    }

    public void push(int value) {
        if (top >= values.length) { // must grow?
            int[] temp = new int[values.length*2];
            System.arraycopy(values,0,temp,0,values.length);
            values = temp;
        }
        values[top++] = value;
    }

    public int pop() {
        if (top > 0) return values[--top];
        throw new IllegalArgumentException("Stack underflow");
    }

    public int get(int index) {
        if (0 <= index && index < top) return values[index];
        throw new IllegalArgumentException("Stack index out of bounds");
    }

    public int getTop() {
        return top;
    }

    public boolean isEmpty() {
        return top == 0;
    }
    
    public void clear() {
        top = 0;
    }
    
    public int compareTo(Object other) {
        IntStack that = (IntStack) other;
        int min = top;
        if (min < that.top) min = that.top;
        for (int i = 0; i < min; ++i) {
            int result = values[i] - that.values[i];
            if (result != 0) return result;
        }
        return top - that.top;
    }

    public boolean equals(Object other) {
        return compareTo(other) == 0;
    }

    public int hashCode() {
        int result = top;
        for (int i = 0; i < top; ++i) {
            result = result * 37 + values[i];
        }
        return result;
    }
}