/*----------------------------------------------------------------------------*/
/*                                                                            */
/* Copyright (c) 1995, 2004 IBM Corporation. All rights reserved.             */
/* Copyright (c) 2005-2014 Rexx Language Association. All rights reserved.    */
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/* This program and the accompanying materials are made available under       */
/* the terms of the Common Public License v1.0 which accompanies this         */
/* distribution. A copy is also available at the following address:           */
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/* notice, this list of conditions and the following disclaimer.              */
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/* the documentation and/or other materials provided with the distribution.   */
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/* of its contributors may be used to endorse or promote products             */
/* derived from this software without specific prior written permission.      */
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/*----------------------------------------------------------------------------*/
#ifndef DBLQUEUE
#define DBLQUEUE
//#define MYDEBUG
#include <stdio.h>
#include "regexp.hpp"

class doubleQueue {
  public:
    doubleQueue(int n);                    // create queue with size n
    ~doubleQueue();
    void push(int value);                  // push on top
    void put(int value);                   // insert at bottom
    int pop();                             // pop from top
    // queue is empty when only one SCAN element is in it
    bool isEmpty() {
      if (head+1 == tail-1 && (memory[tail-1] == SCAN)) return true;
      else return false;
    }
#ifdef MYDEBUG
    // show contents of queue
    void dump() {
      printf("double queue: {");
      for (int i=head+1;i<tail;i++) {
        if (memory[i] == SCAN) printf("SCAN");
        else printf("%d",memory[i]);
        if (i < tail-1) printf(", ");
      }
      printf("}\n");
    }
#endif

  private:
    void enlarge();                        // make int array bigger if needed

    int *memory;                           // array holding elements of queue
    int size;                              // size of array
    int head;                              // position of head of queue
    int tail;                              // position of tail of queue
};

#endif
