C++ concepts: MoveInsertable (since C++11)
Specifies that an object of the type can be constructed into uninitialized storage from an rvalue of that type by a given allocator.
[edit] Requirements
The type T is MoveInsertable into the container X whose value_type is identical to T if, given
A
|
an allocator type |
m
|
an lvalue of type A
|
p
|
the pointer of type T* prepared by the container
|
rv
|
rvalue expression of type T
|
where X::allocator_type is identical to std::allocator_traits<A>::rebind_alloc<T>,
the following expression is well-formed:
std::allocator_traits<A>::construct(m, p, rv);
And after evaluation, the value of *p is equivalent to the value formerly held by rv (rv remains valid, but is in an unspecified state.)
If X is not allocator-aware, the term is defined as if A were std::allocator<T>, except that no allocator object needs to be created, and user-defined specializations of std::allocator are not instantiated.
[edit] Notes
If A is std::allocator<T>, then this will call placement-new, as by ::new((void*)p) T(rv).
If std::allocator<T> or a similar allocator is used, a class does not have to implement a move constructor to satisfy this type requirement: a copy constructor that takes a const T& argument can bind rvalue expressions. If a MoveInsertable class implements a move constructor, it may also implement move semantics to take advantage of the fact that the value of rv after construction is unspecified.
[edit] See Also
CopyInsertable
|