Stack.cpp

#include "Stack.h"
#include "require.h"
using namespace std;

void
Stack::Link::initialize(void* dat, Link* nxt) {
  data = dat;
  next = nxt;
}

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

void Stack::push(void* dat) {
  Link* newLink = new Link;
  newLink->initialize(dat, head);
  head = newLink;
}

void* Stack::peek() {
  require(head != 0, "Stack empty");
  return head->data;
}

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

void Stack::cleanup() {
  require(head == 0, "Stack not empty");
} ///:~