stack3.cpp

Thinking_in_C___2.rar

//: C06:Stack3.cpp {O}
// From Thinking in C++, 2nd Edition
// at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// Constructors/destructors
#include <cstdlib>
#include "../require.h"
#include "Stack3.h"
using namespace std;

void Stack::link::initialize(
  void* Data, link* Next) {
  data = Data;
  next = Next;
}

Stack::Stack() { head = 0; }

void Stack::push(void* Data) {
  // Can't use a constructor with malloc!
  link* newlink = (link*)malloc(sizeof(link));
  require(newlink);
  newlink->initialize(Data, head);
  head = newlink;
}

void* Stack::peek() { return head->data; }

void* Stack::pop() {
  if(head == 0) return 0;
  void* result = head->data;
  link* oldHead = head;
  head = head->next;
  free(oldHead);
  return result;
}

Stack::~Stack() {
  link* cursor = head;
  while(head) {
    cursor = cursor->next;
    free(head->data); // Assumes malloc!
    free(head);
    head = cursor;
  }
} ///:~