stack和queue底层都是封装了deque,然后调用部分deque的函数实现自己的功能,因为本质上来说stack和queue是单向变化的deque.
template<class T, class Sequence = stack<T> > class stack{ ... public: 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 e; public: bool empty() const{return e.empty();} size_type size()const{return e.size();} reference top(){return e.back();} const_reference top(){return e.back();} void push(const value_type& x){e.push_back(x);} void pop(){e.pop_back();} };
template<class T, class Sequence = deque<T> > class queue{ ... public: 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 e; public: bool empty() const{return e.empty();} size_type size()const{return e.size();} reference front(){return e.front();} const_reference front(){return e.front();} reference back(){return e.back();} const_reference back() const{return e.back();} void push(const value_type& x){e.push_back(x);} void pop(){e.pop_front();} };
因为queue和stack封装了deque,但是因为是受限段的移动方向,因此规定satck和queue是不可以随意使用iterator,也不会提供iterator.
侯捷老师