STL學習--stack

簡介

stack是一中後入先出（LIFO）的數據結構，它只有一個出口，只可以對頂端元素進行操作。STL底層默認基於deque容器實現。

在創建適配器時，通過將一個順序容器指定爲適配器的第二個類型實參，可覆蓋默認的容器類型。

stack< string, vector<string> > str_stk; // 由vector實現的stack

stack< string, list<string> > str_stk; // 由list實現的stack

stack是由底部容器完成的所有操作，因此是容器適配器。

特性

後入先出（LIFO）

只可對頂端元素進行操作，沒有迭代器。

常用操作

s.empty()	如果棧爲空，則返回 true，否則返回 stack
s.size()	返回棧中元素的個數
s.pop()	刪除棧頂元素的值，但不返回其值
s.top()	返回棧頂元素的值，但不刪除該元素
s.push(item)	在棧頂壓入新元素

源碼（STL3.3）

/*
 *
 * 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

#include <sequence_concepts.h>

__STL_BEGIN_NAMESPACE

// Forward declarations of operators == and <, needed for friend declaration.

template <class _Tp, 
          class _Sequence __STL_DEPENDENT_DEFAULT_TMPL(deque<_Tp>) >
class stack;

template <class _Tp, class _Seq>
bool operator==(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y);

template <class _Tp, class _Seq>
bool operator<(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y);


template <class _Tp, class _Sequence>
class stack {

  // requirements:

  __STL_CLASS_REQUIRES(_Tp, _Assignable);
  __STL_CLASS_REQUIRES(_Sequence, _BackInsertionSequence);
  typedef typename _Sequence::value_type _Sequence_value_type;
  __STL_CLASS_REQUIRES_SAME_TYPE(_Tp, _Sequence_value_type);


#ifdef __STL_MEMBER_TEMPLATES
  template <class _Tp1, class _Seq1>
  friend bool operator== (const stack<_Tp1, _Seq1>&,
                          const stack<_Tp1, _Seq1>&);
  template <class _Tp1, class _Seq1>
  friend bool operator< (const stack<_Tp1, _Seq1>&,
                         const stack<_Tp1, _Seq1>&);
#else /* __STL_MEMBER_TEMPLATES */
  friend bool __STD_QUALIFIER
  operator== __STL_NULL_TMPL_ARGS (const stack&, const stack&);
  friend bool __STD_QUALIFIER
  operator< __STL_NULL_TMPL_ARGS (const stack&, const stack&);
#endif /* __STL_MEMBER_TEMPLATES */

public:
  typedef typename _Sequence::value_type      value_type;
  typedef typename _Sequence::size_type       size_type;
  typedef          _Sequence                  container_type;

  typedef typename _Sequence::reference       reference;
  typedef typename _Sequence::const_reference const_reference;
protected:
  _Sequence c;
public:
  stack() : c() {}
  explicit stack(const _Sequence& __s) : c(__s) {}

  bool empty() const { return c.empty(); }
  size_type size() const { return c.size(); }
  reference top() { return c.back(); }
  const_reference top() const { return c.back(); }
  void push(const value_type& __x) { c.push_back(__x); }
  void pop() { c.pop_back(); }
};

template <class _Tp, class _Seq>
bool operator==(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y)
{
  return __x.c == __y.c;
}

template <class _Tp, class _Seq>
bool operator<(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y)
{
  return __x.c < __y.c;
}

#ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER

template <class _Tp, class _Seq>
bool operator!=(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y)
{
  return !(__x == __y);
}

template <class _Tp, class _Seq>
bool operator>(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y)
{
  return __y < __x;
}

template <class _Tp, class _Seq>
bool operator<=(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y)
{
  return !(__y < __x);
}

template <class _Tp, class _Seq>
bool operator>=(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y)
{
  return !(__x < __y);
}

#endif /* __STL_FUNCTION_TMPL_PARTIAL_ORDER */

__STL_END_NAMESPACE

#endif /* __SGI_STL_INTERNAL_STACK_H */

// Local Variables:
// mode:C++
// End: