tstack.h

Think in C++文中代码实现

// File from page 598 in "Thinking in C++" by Bruce Eckel
//////////////////////////////////////////////////
// From the compressed package ECKELT02.ZIP 4/11/95
// (Original ECKELT01.ZIP dated 2/21/95)
// Copyright (c) Bruce Eckel, 1995 
// Source code file from the book "Thinking in C++", 
// Prentice Hall, 1995, ISBN: 0-13-917709-4
// All rights reserved EXCEPT as allowed by the following 
// statements: You may freely use this file for your own 
// work, including modifications and distribution in 
// executable form only. You may copy and distribute this 
// file, as long as it is only distributed in the complete 
// (compressed) package with the other files from this 
// book and you do not remove this copyright and notice. 
// You may not distribute modified versions of the source 
// code in this package. This package may be freely placed 
// on bulletin boards, internet nodes, shareware disks and 
// product vendor disks. You may not use this file in 
// printed media without the express permission of the 
// author. Bruce Eckel makes no 
// representation about the suitability of this software 
// for any purpose. It is provided "as is" without express 
// or implied warranty of any kind. The entire risk as to 
// the quality and performance of the software is with 
// you. Should the software prove defective, you assume 
// the cost of all necessary servicing, repair, or 
// correction. 
// If you think you've found an error, please 
// email all modified files with loudly commented changes 
// to: [e-mail] (please use the same 
// address for non-code errors found in the book).
//////////////////////////////////////////////////

//: TSTACK.H -- Stack using templates
#ifndef TSTACK_H_
#define TSTACK_H_

// Declaration required:
template<class T> class tstackIterator;

template<class T>
class tstack {
  struct link {
    T* data;
    link* next;
    link(T* Data, link* Next) {
      data = Data;
      next = Next;
    }
  } * head;
  int owns;
public:
  tstack(int Owns = 1) : head(0), owns(Owns) {}
  ~tstack();
  void push(T* Data) {
    head = new link(Data,head);
  }
  T* peek() const { return head->data; }
  T* pop();
  int Owns() const { return owns; }
  void Owns(int newownership) {
    owns = newownership;
  }
  friend class tstackIterator<T>;
};

template<class T>
T* tstack<T>::pop() {
  if(head == 0) return 0;
  T* result = head->data;
  link* oldHead = head;
  head = head->next;
  delete oldHead;
  return result;
}

template<class T>
tstack<T>::~tstack() {
  link* cursor = head;
  while(head) {
    cursor = cursor->next;
    // Conditional cleanup of data:
    if(owns) delete head->data;
    delete head;
    head = cursor;
  }
}

template<class T>
class tstackIterator {
  tstack<T>::link* p;
public:
  tstackIterator(const tstack<T>& tl)
    : p(tl.head) {}
  tstackIterator(const tstackIterator& tl)
    : p(tl.p) {}
  // operator++ returns boolean indicating end:
  int operator++() {
    if(p->next)
      p = p->next;
    else p = 0; // Indicates end of list
    return int(p);
  }
  int operator++(int) { return operator++(); }
  // Smart pointer:
  T* operator->() const {
    if(!p) return 0;
    return p->data;
  }
  T* current() const {
    if(!p) return 0;
    return p->data;
  }
  // int conversion for conditional test:
  operator int() const { return p ? 1 : 0; }
};
#endif // TSTACK_H_