std::uninitialized_move

Defined in header `<memory>`
template< class InputIt, class ForwardIt > ForwardIt uninitialized_move( InputIt first, InputIt last, ForwardIt d_first );	(1)	(since C++17)
template< class ExecutionPolicy, class InputIt, class ForwardIt > ForwardIt uninitialized_move( ExecutionPolicy&& policy, InputIt first, InputIt last, ForwardIt d_first );	(2)	(since C++17)

1) Moves elements from the range [first, last) to an uninitialized memory area beginning at d_first as if by

for (; first != last; ++d_first, (void) ++first)
   ::new (static_cast<void*>(std::addressof(*d_first)))
      typename std::iterator_traits<ForwardIt>::value_type(std::move(*first));

If an exception is thrown during the initialization, some objects in [first, last) are left in a valid but unspecified state.

2) Same as (1), but executed according to policy. This overload does not participate in overload resolution unless std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true

first, last	-	the range of the elements to move
d_first	-	the beginning of the destination range
policy	-	the execution policy to use. See execution policy for details.
Type requirements
- `InputIt` must meet the requirements of `InputIterator`.
- `ForwardIt` must meet the requirements of `ForwardIterator`.
- No increment, assignment, comparison, or indirection through valid instances of `ForwardIt` may throw exceptions.

[edit] Return value

Iterator to the element past the last element moved.

[edit] Complexity

Linear in the distance between first and last

[edit] Exceptions

The overload with a template parameter named ExecutionPolicy reports errors as follows:

If execution of a function invoked as part of the algorithm throws an exception, std::terminate is called.
If the algorithm fails to allocate memory, std::bad_alloc is thrown.

[edit] Possible implementation

template<class InputIt, class ForwardIt>
ForwardIt uninitialized_move(InputIt first, InputIt last, ForwardIt d_first)
{
    typedef typename std::iterator_traits<ForwardIt>::value_type Value;
    ForwardIt current = d_first;
    try {
        for (; first != last; ++first, (void) ++current) {
            ::new (static_cast<void*>(std::addressof(*current))) Value(std::move(*first));
        }
        return current;
    } catch (...) {
        for (; d_first != current; ++d_first) {
            d_first->~Value();
        }
        throw;
    }
}

[edit] Example

[edit] See also

uninitialized_copy	copies a range of objects to an uninitialized area of memory (function template)
uninitialized_move_n (C++17)	moves a number of objects to an uninitialized area of memory (function template)

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