Created
May 14, 2018 16:03
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#include <iterator> | |
namespace Hard1 { | |
/** | |
* template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t, | |
* typename _Pointer = _Tp*, typename _Reference = _Tp&> | |
* Это шаблон std::iterator. | |
* Т.к. insert-итераторы не указывают на объект какого-то типа, то _Tp следует сделать | |
* void. | |
*/ | |
template <typename Container> | |
class back_insert_iterator : std::iterator<std::output_iterator_tag, void, void, void, void> { | |
private: | |
Container* container_; | |
public: | |
typedef Container container_type; | |
back_insert_iterator(Container& container) : | |
container_(&container) {} | |
/** | |
* Итератор не предоставляет доступ к какому-либо значению, | |
* так же нет смысла его копировать, т.к. все итераторы на один контейнер будут одинаковые. | |
*/ | |
back_insert_iterator& operator*() { return *this; } | |
back_insert_iterator& operator++() { return *this; } | |
back_insert_iterator operator++(int) { return *this; } | |
back_insert_iterator& operator=(const typename Container::value_type& x) { | |
container_->push_back(x); | |
return *this; | |
} | |
/** | |
* x - lvalue(т.к. x имеет имя), тип x - rvalue-ссылка на x | |
* Потому надо привести к value_type&&, т.е. сделать std::move. | |
*/ | |
back_insert_iterator& operator=(typename Container::value_type&& x) { | |
container_->push_back(std::move(x)); | |
return *this; | |
} | |
}; | |
template <typename Container> | |
inline back_insert_iterator<Container> back_inserter(Container& container) { | |
return back_insert_iterator<Container>(container); | |
} | |
template <typename Container> | |
class front_insert_iterator : std::iterator<std::output_iterator_tag, void, void, void, void> { | |
private: | |
Container* container_; | |
public: | |
typedef Container container_type; | |
front_insert_iterator(Container& container) : | |
container_(&container) {} | |
front_insert_iterator& operator*() { return *this; } | |
front_insert_iterator& operator++() { return *this; } | |
front_insert_iterator operator++(int) { return *this; } | |
front_insert_iterator& operator=(const typename Container::value_type& x) { | |
container_->push_back(x); | |
return *this; | |
} | |
front_insert_iterator& operator=(typename Container::value_type&& x) { | |
container_->push_front(std::move(x)); | |
return *this; | |
} | |
}; | |
template <typename Container> | |
inline front_insert_iterator<Container> back_inserter(Container& container) { | |
return front_insert_iterator<Container>(container); | |
} | |
template <typename Container, typename Iterator> | |
class insert_iterator : std::iterator<std::output_iterator_tag, void, void, void, void> { | |
private: | |
Container* container_; | |
Iterator iterator_; | |
public: | |
typedef Container container_type; | |
typedef Iterator iterator_type; | |
insert_iterator(Container& container, Iterator iterator) : | |
container_(&container), iterator_(iterator) {} | |
insert_iterator& operator*() { return *this; } | |
insert_iterator& operator++() { return *this; } | |
insert_iterator operator++(int) { return *this; } | |
front_insert_iterator& operator=(const typename Container::value_type& x) { | |
container_->insert(iterator_, x); | |
return *this; | |
} | |
front_insert_iterator& operator=(typename Container::value_type&& x) { | |
container_->insert(iterator_, std::move(x)); | |
return *this; | |
} | |
}; |
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