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  1. /*
  2.  * Copyright (c) 2008, Manuel Mausz <manuel at mausz.at>
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions are met:
  7.  *     * Redistributions of source code must retain the above copyright
  8.  *       notice, this list of conditions and the following disclaimer.
  9.  *     * Redistributions in binary form must reproduce the above copyright
  10.  *       notice, this list of conditions and the following disclaimer in the
  11.  *       documentation and/or other materials provided with the distribution.
  12.  *     * Neither the name of the copyright holders nor the
  13.  *       names of its contributors may be used to endorse or promote products
  14.  *       derived from this software without specific prior written permission.
  15.  *
  16.  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17.  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18.  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19.  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20.  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  22.  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
  23.  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  24.  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
  25.  * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
  26.  * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
  27.  * DAMAGE.
  28.  */
  29.  
  30. /**
  31.  * Implements a stack using an array
  32.  *
  33.  * @version 1.0
  34.  * @author  Manuel Mausz (manuel at mausz.at)
  35.  * @author  http://manuel.mausz.at/
  36.  */
  37. class Stack
  38. {
  39.   private int[] stack;
  40.   private int i = 0;
  41.  
  42.   /**
  43.    * constructor
  44.    *
  45.    * @param size initialize stack size
  46.    */
  47.   Stack(int size)
  48.   {
  49.     stack = new int[size];
  50.   }
  51.  
  52.   public void resize()
  53.   {
  54.     resize(2);
  55.   }
  56.  
  57.   /**
  58.    * resizes the internal stack
  59.    *
  60.    * @param factor resize factor. default is 2
  61.    */
  62.   public void resize(int factor)
  63.   {
  64.     if (factor <= 1)
  65.       return;
  66.     int b[] = stack.clone();
  67.     stack = new int[stack.length * factor];
  68.     System.arraycopy(b, 0, stack, 0, i);
  69.   }
  70.  
  71.   /**
  72.    * push item onto stack
  73.    *
  74.    * @param n item
  75.    */
  76.   public void push(int n)
  77.   {
  78.     if (i >= stack.length)
  79.       resize();
  80.     stack[i++] = n;
  81.   }
  82.  
  83.   /**
  84.    * pop item from stack
  85.    *
  86.    * @return item
  87.    */
  88.   public int pop()
  89.   {
  90.     if (i == 0)
  91.       return 0;
  92.     return stack[--i];
  93.   }
  94.  
  95.   /**
  96.    * check if stack has items
  97.    *
  98.    * @return boolean
  99.    */
  100.   public boolean hasNext()
  101.   {
  102.     return (i > 0);
  103.   }
  104.  
  105.   /**
  106.    * converts stack to string
  107.    *
  108.    * @return string
  109.    */
  110.   public String toString()
  111.   {
  112.     String str = "";
  113.     for (int j = 0; j < i; j++)
  114.       str += stack[j] + "\n";
  115.     return str;
  116.   }
  117. }
  118.