C++ named requirements: CopyInsertable (since C++11)
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C++ named requirements
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++17)
(C++11)
(C++11)
CopyInsertable
(C++11)
(C++11)
(C++11)
(C++11)
(C++17)
(C++20)
(C++20)
(C++20)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++14)
(C++14)
(C++11)
(C++11)
(C++17)
(C++14)
(C++20)
(C++20)
(C++23)
(C++23)
(C++23)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Specifies that an object of the type can be copy-constructed in-place by a given allocator.
[edit] Requirements
Given the following types, values and expressions:
Type
Definition
T
an object type
A
an allocator type
X
a container type satisfying all following conditions:
-
X::value_typeis the same asT. -
X::allocator_typeis the same as std::allocator_traits <A>::rebind_alloc<T>.
Value
Definition
m
an lvalue of type
A
p
a pointer of type
T*
Expression
Definition
v
an expression denoting an lvalue of type
T / const T, or an rvalue of type const T
expr
std::allocator_traits <A>::construct(m, p, v)
T is CopyInsertable into X if all following conditions are satisfied:
-
Tis MoveInsertable intoX. - expr is well-formed.
- Evaluating expr does not change the value of v.
- Right after the evaluation of expr, the value of v is equivalent to *p.
[edit] Notes
If A is std::allocator <T>, then this will call placement new, as by ::new((void*)p) T(v)(until C++20)std::construct_at (p, v)(since 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.
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2177 | C++11 | evaluting expr did not have any postcondition | added |
| LWG 3957 | C++11 | v could denote an rvalue of type T
|
excluded |