stack.h

/****************************************/
//  QT Paint
//  File: stack.h
//  Author: Hong Joon Choi
//  Date: 25.Mar.2015
//  Description: the header file
//  -- Stack class declaration + definition. Stack implemented by array.
//     template implementation of stack data structure for multiple-level undo and redo
//
//    NOTE: pop() function returns pointer of an object, and it DOES NOT automatically release memory. Attention is required when using pop()
//    NOTE: push() function makes a copy of an object and stores inside the stack.
/****************************************/

#include <iostream>

#ifndef _STACK_H
#define _STACK_H



template <class Type>
class Stack
{
public:
   /** constructor and destructor */
   Stack()  // 1 level for default
   {
      max_size=1;
      items = new Type*[max_size];
      top_index = -1;
   }
   Stack(int max)
   {
      max_size=max;
      items = new Type*[max_size];
      top_index = -1;

   }
   ~Stack()
   {
      for (int i=0; i<= top_index; i++)
         delete items[i];
      delete[] items;
   }

   /** reset all data members */
   void reset()
   {
      for (int i=0; i <= top_index; i++)
      {
         delete items[i];
         items[i] = NULL;
         //std::cout << " one item deleted from stack!" << std::endl;
      }
      top_index = -1;
   }


   /** push, pop, isEmpty, isFull */
   void push(Type item)    // add one object item to stack. IF STACK IS FULL, ITEM AT THE BOTTOM IS DELETED BEFORE NEW ONE GETS ADDED.
   {
      
      if (!isFull())
         items[++top_index] = new Type(item);
      else
      {
         //std::cout << " one item deleted from stack!" << std::endl;
         delete items[0];
         for (int i=0; i < top_index; i++)
            items[i] = items[i+1];
         items[top_index] = new Type(item);
      }
      //std::cout << " one item added to stack!" << std::endl;
   }

   Type* pop()    // returns pointer of top object from the stack.
   {
      //std::cout << " stack.pop() called. Returned item as pointer" << std::endl;
      if (!isEmpty())
         return items[top_index--];
      else
         return NULL;
   }

   bool isEmpty() const{return top_index == -1;}

   bool isFull() const{return top_index == max_size - 1;}

   int size() const{ return top_index+1;}

private:
   Type** items;
   int top_index;
   int max_size;

};


#endif