标准库中的-stack

 #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: