Class template move_iterator is an iterator adaptor with the same behavior as the underlying iterator except that its indirection operator implicitly converts the value returned by the underlying iterator's indirection operator to an rvalue reference. Some generic algorithms can be called with move iterators to replace copying with moving.
[ Example:
list<string> s; // populate the list s vector<string> v1(s.begin(), s.end()); // copies strings into v1 vector<string> v2(make_move_iterator(s.begin()), make_move_iterator(s.end())); // moves strings into v2
— end example ]
namespace std {
template <class Iterator>
class move_iterator {
public:
typedef Iterator iterator_type;
typedef typename iterator_traits<Iterator>::difference_type difference_type;
typedef Iterator pointer;
typedef typename iterator_traits<Iterator>::value_type value_type;
typedef typename iterator_traits<Iterator>::iterator_category iterator_category;
typedef value_type&& reference;
move_iterator();
explicit move_iterator(Iterator i);
template <class U> move_iterator(const move_iterator<U>& u);
template <class U> move_iterator& operator=(const move_iterator<U>& u);
iterator_type base() const;
reference operator*() const;
pointer operator->() const;
move_iterator& operator++();
move_iterator operator++(int);
move_iterator& operator--();
move_iterator operator--(int);
move_iterator operator+(difference_type n) const;
move_iterator& operator+=(difference_type n);
move_iterator operator-(difference_type n) const;
move_iterator& operator-=(difference_type n);
unspecified operator[](difference_type n) const;
private:
Iterator current; // exposition only
};
template <class Iterator1, class Iterator2>
bool operator==(
const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
template <class Iterator1, class Iterator2>
bool operator!=(
const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
template <class Iterator1, class Iterator2>
bool operator<(
const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
template <class Iterator1, class Iterator2>
bool operator<=(
const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
template <class Iterator1, class Iterator2>
bool operator>(
const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
template <class Iterator1, class Iterator2>
bool operator>=(
const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
template <class Iterator1, class Iterator2>
auto operator-(
const move_iterator<Iterator1>& x,
const move_iterator<Iterator2>& y) -> decltype(x.base() - y.base());
template <class Iterator>
move_iterator<Iterator> operator+(
typename move_iterator<Iterator>::difference_type n, const move_iterator<Iterator>& x);
template <class Iterator>
move_iterator<Iterator> make_move_iterator(Iterator i);
}
The template parameter Iterator shall meet the requirements for an Input Iterator ([input.iterators]). Additionally, if any of the bidirectional or random access traversal functions are instantiated, the template parameter shall meet the requirements for a Bidirectional Iterator ([bidirectional.iterators]) or a Random Access Iterator ([random.access.iterators]), respectively.
Effects: Constructs a move_iterator, value initializing current. Iterator operations applied to the resulting iterator have defined behavior if and only if the corresponding operations are defined on a value-initialized iterator of type Iterator.
explicit move_iterator(Iterator i);
Effects: Constructs a move_iterator, initializing current with i.
template <class U> move_iterator(const move_iterator<U>& u);
Effects: Constructs a move_iterator, initializing current with u.base().
Requires: U shall be convertible to Iterator.
template <class U> move_iterator& operator=(const move_iterator<U>& u);
Effects: Assigns u.base() to current.
Requires: U shall be convertible to Iterator.
Returns: std::move(*current).
Returns: current.
Effects: ++current.
Returns: *this.
move_iterator operator++(int);
Effects:
move_iterator tmp = *this; ++current; return tmp;
Effects: --current.
Returns: *this.
move_iterator operator--(int);
Effects:
move_iterator tmp = *this; --current; return tmp;
move_iterator operator+(difference_type n) const;
Returns: move_iterator(current + n).
move_iterator& operator+=(difference_type n);
Effects: current += n.
Returns: *this.
move_iterator operator-(difference_type n) const;
Returns: move_iterator(current - n).
move_iterator& operator-=(difference_type n);
Effects: current -= n.
Returns: *this.
unspecified operator[](difference_type n) const;
Returns: std::move(current[n]).
template <class Iterator1, class Iterator2>
bool operator==(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
Returns: x.base() == y.base().
template <class Iterator1, class Iterator2>
bool operator!=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
Returns: !(x == y).
template <class Iterator1, class Iterator2>
bool operator<(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
Returns: x.base() < y.base().
template <class Iterator1, class Iterator2>
bool operator<=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
Returns: !(y < x).
template <class Iterator1, class Iterator2>
bool operator>(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
Returns: y < x.
template <class Iterator1, class Iterator2>
bool operator>=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
Returns: !(x < y).
template <class Iterator1, class Iterator2>
auto operator-(
const move_iterator<Iterator1>& x,
const move_iterator<Iterator2>& y) -> decltype(x.base() - y.base());
Returns: x.base() - y.base().
template <class Iterator>
move_iterator<Iterator> operator+(
typename move_iterator<Iterator>::difference_type n, const move_iterator<Iterator>& x);
Returns: x + n.
template <class Iterator>
move_iterator<Iterator> make_move_iterator(Iterator i);
Returns: move_iterator<Iterator>(i).