Assignment 3 Solutions

CSCI 132 Data Structures--Spring 2014

Assignment 3 Solutions
Solution to deque.cc code:
/****************************************************
 * File Name: deque.cc
 * Author: Brenda Student
 * Course: CSCI 132
 * Assignment: Homework 3
 * Purpose: Implementation of Queue class
 * Date: February 13, 2014
 *****************************************************/

#include "deque.h"

Deque::Deque()  //optional
/*
  Pre: None
  Post: The Deque is initialized to be empty.
*/
{ 
	//nothing to initialize
}

Error_code Deque::append_front(const Queue_entry &item)
/*
Pre: The deque is not full
Post: item is added to the front of the Deque. If the Deque is full
return an Error_code of overflow.
*/
{
  if (count >= maxqueue) {
    return overflow;
  }
  if (front == 0) {
  	front = maxqueue -1;
  } else {
  	front = front -1;
  }
  entry[front] = item;
  count ++;
  return success;
}

Error_code Deque::serve_front()
/*
Pre: the deque has at least one entry
Post: The front of the Deque is removed. If the Deque
is empty return an Error_code of underflow.
*/
{
  return serve();        //Or could write Queue::serve();
}

Error_code Deque::retrieve_front(Queue_entry &item)const
/*
Pre: The deque has at least one entry
Post: The front of the Deque retrieved to the output parameter item.
If the Deque is empty return an Error_code of underflow.
*/
{
  return retrieve(item);
}

Error_code Deque::append_rear(const Queue_entry &item)
/*
Pre: The deque is not full
Post: item is added to the rear of the Deque. If the Deque is full
return an Error_code of overflow.
*/
{
  return append(item);
}

Error_code Deque::serve_rear()
/*
Pre: The deque has at least one entry
Post: The rear of the Deque is removed. If the Deque
is empty return an Error_code of underflow.
*/
{
  if (count <= 0)
    return underflow;
  if (rear == 0) {
  	rear = maxqueue -1;
  } else {
  	rear = rear -1;
  }
  count --;
  return success;
}

Error_code Deque::retrieve_rear(Queue_entry &item)const
/*
Pre: Deque has at least one entry
Post: The rear of the Deque retrieved to the output parameter item.
If the Deque is empty return an Error_code of underflow.
*/
{
  if (count <= 0)
    return underflow;
  item = entry[rear];
  return success;
}