LinkedStack.cpp - VTC C++ Linked Stack

/**
 * [LinkedStack.cpp]
 * The LinkedStack class definition/implementation.
 */

#include "LinkedStack.h"

/**
 * LinkedStack CLASS CONSTRUCTOR(s):
 */
LinkedStack::LinkedStack()
{
    top = 0;
}


/**
 * LinkedStack CLASS ACCESSORS:
 */
void LinkedStack::Pop(float &item)
{
    Node    *pTemp;         // creates a new node to point to the element being popped off the stack

    item = top->element;    // stores the element being popped off the stack
    pTemp = top;            // moves the current top of the stack to the temporary pointer
    top = top->next;        // points the current top of the stack to the new top

    delete pTemp;           // deletes the temporary pointer (destroying the element being popped off the stack)

    /**
     * NOTE:
     * The code implemented here facilitates the popping of elements from the beginning of the stack
     * ALWAYS.
     */
}


/**
 * LinkedStack CLASS MUTATORS:
 */
void LinkedStack::Push(float item)
{
    Node    *newNode = new Node();  // creates a new node to assign the item to be pushed onto the stack to

    newNode->element = item;        // assigns the item to be pushed onto the top of the stack to the element part of the new node
    newNode->next = top;            // points the next of the new node to the (new) top of the stack (because the item will be added before the top)
    top = newNode;                  // points the current top of the stack to the new node
}


/**
 * LinkedStack CLASS GENERAL USE FUNCTIONS:
 */
void LinkedStack::MakeEmpty(void)
{
    Node    *tempPtr;           // a temporary pointer to point to nodes (elements) to be removed from the stack

        while(top != 0)         // while the stack still contains elements
        {
            tempPtr = top;      // moves the (current) top of the stack to a temporary pointer
            top = top->next;    // moves the top to the next element on the stack (creating the new top)

            delete tempPtr;     // deletes the previous top element of the stack
        }
}

bool LinkedStack::IsEmpty(void)
{
    return (top == 0);          // if the top is null, true will be returned, indicating an empty stack, otherwise, false
}

bool LinkedStack::IsFull(void)
{
    Node    *pTemp = new Node();    // try to allocate memory for a temporary node

        if(pTemp == 0)  // if the attempted memory allocation failed...
            return true;            // ...true is returned, indicating a full stack
        else            // ...
        {
            delete pTemp;           // removes the temporary pointer

            return false;           // ...false is returned
        }
}

/**
 * LinkedStack CLASS DESTRUCTOR
 */
LinkedStack::~LinkedStack()
{
    MakeEmpty();
}