// Filename: stl_stack.h
// Comment By: 凝霜
// E-mail: mdl2009@vip.qq.com
// Blog: http://blog.csdn.net/mdl13412
////////////////////////////////////////////////////////////////////////////////
// stack是一種先進後出(First In Last Out, FILO)的資料結構, 其只有一個出口
// 支援對棧頂元素的追加, 彈出, 獲取, 但是不提供對其它位置元素的訪問
////////////////////////////////////////////////////////////////////////////////
// 以下為使用deque時的佈局
//
// 棧底 當前棧頂 預留的記憶體邊界
// ↓ ↓ ↓
// --------------------------------------------------------------------
// | | | ...... | | | | | | | | ...... | | | X |
// --------------------------------------------------------------------
// ↑ ↑ ↑
// | | |
// | -------------------------------
// | 這裡是尚未使用的預留記憶體, 可能為0
// |
// 僅支援在這裡進行push(), pop(), top()操作
////////////////////////////////////////////////////////////////////////////////
/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996,1997
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/
/* NOTE: This is an internal header file, included by other STL headers.
* You should not attempt to use it directly.
*/
#ifndef __SGI_STL_INTERNAL_STACK_H
#define __SGI_STL_INTERNAL_STACK_H
__STL_BEGIN_NAMESPACE
// 如果編譯器不能根據前面模板引數推匯出後面使用的預設引數型別,
// 那麼就需要手工指定, 本實作stack內部容器預設使用deque
// 選用deque可以在儲存空間不足時可以動態增加, 而且代價很低
#ifndef __STL_LIMITED_DEFAULT_TEMPLATES
template <class T, class Sequence = deque<T> >
#else
template <class T, class Sequence>
#endif
class stack
{
// 特化的全域性運算子, 提供operator==和<過載則構建出所有運算子
// 其具體細節見<stl_pair.h>中的說明
friend bool operator== __STL_NULL_TMPL_ARGS (const stack&, const stack&);
friend bool operator< __STL_NULL_TMPL_ARGS (const stack&, const stack&);
public:
// 由於stack僅支援對棧頂元素的操作, 所以不定義STL要求的
// pointer, iterator, difference_type
typedef typename Sequence::value_type value_type;
typedef typename Sequence::size_type size_type;
typedef typename Sequence::reference reference;
typedef typename Sequence::const_reference const_reference;
protected:
Sequence c; // 這個是我們實際維護的容器
public:
// 下面的操作完全使用內部容器的成員函式實現
// 這再次體現了STL高度的可複用性:-)
// 判斷stack是否為空
bool empty() const { return c.empty(); }
// stack中元素個數
size_type size() const { return c.size(); }
// 返回棧頂元素, 注意這裡返回的是引用!!!
reference top() { return c.back(); }
const_reference top() const { return c.back(); }
// 在棧頂追加新元素
void push(const value_type& x) { c.push_back(x); }
// 移除棧頂元素, 注意不返回元素的引用,
// 很多初學者隨機用此容器時經常誤認為pop()操作同時會返回棧頂元素的引用
void pop() { c.pop_back(); }
};
// 判斷兩個stack是否相等, 就要測試其內部維護容器是否相等
// x.c == y.c會呼叫容器過載的operator ==
template <class T, class Sequence>
bool operator==(const stack<T, Sequence>& x, const stack<T, Sequence>& y)
{
return x.c == y.c;
}
template <class T, class Sequence>
bool operator<(const stack<T, Sequence>& x, const stack<T, Sequence>& y)
{
return x.c < y.c;
}
__STL_END_NAMESPACE
#endif /* __SGI_STL_INTERNAL_STACK_H */
// Local Variables:
// mode:C++
// End: