C++ named requirements: CopyInsertable (od C++11)
Specifies that an instance of the type can be copy-constructed in-place by a given allocator.
Requirements
The type T is CopyInsertable into the container X whose value_type is identical to T if T is MoveInsertable into X, and, given
A
an allocator typem
an lvalue of typeA
p
the pointer of typeT*
prepared by the containerv
expression of type (possibly const) T where X::allocator_type is identical tostd::allocator_traits<A>::rebind_alloc<T>
,
the following expression is well-formed:
std::allocator_traits<A>::construct(m, p, v);
And after evaluation, the value of *p
is equivalent to the value of v
. The value of v
is unchanged.
If X is not allocator-aware or is a std::basic_string specialization, 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.
Notes
If A is std::allocator<T>, then this will call placement-new,
as by ::new((void*)p) T(v)
(do C++20) std::construct_at(p, v)
(od C++20)
Although it is required that customized construct is used when constructing elements of std::basic_string until C++23, all implementations only used the default mechanism. The requirement is corrected by P1072R10 to match existing practice.