allocate_proxy
The definition of allocate_proxy
makes use of an exposition-only class template allocated-ptr. An object of type allocated-ptr<T, Alloc>
allocates the storage for another object of type T
with an allocator of type Alloc
and manages the lifetime of this contained object. Similar to std::optional
, allocated-ptr<T, Alloc>
provides operator*
for accessing the managed object of type T
with the same qualifiers, but does not necessarily support the state where the contained object is absent.
// (1)
template <facade F, class T, class Alloc, class... Args>
proxy<F> allocate_proxy(const Alloc& alloc, Args&&... args); // freestanding-deleted
// (2)
template <facade F, class T, class Alloc, class U, class... Args>
proxy<F> allocate_proxy(const Alloc& alloc, std::initializer_list<U> il, Args&&... args); // freestanding-deleted
// (3)
template <facade F, class Alloc, class T>
proxy<F> allocate_proxy(const Alloc& alloc, T&& value); // freestanding-deleted
(1)
Creates a proxy<F>
object containing a value p
of type allocated-ptr<T, Alloc>
, where *p
is direct-non-list-initialized with std::forward<Args>(args)...
.
(2)
Creates a proxy<F>
object containing a value p
of type allocated-ptr<T, Alloc>
, where *p
is direct-non-list-initialized with il, std::forward<Args>(args)...
.
(3)
Creates a proxy<F>
object containing a value p
of type allocated-ptr<std::decay_t<T>, Alloc>
, where *p
is direct-non-list-initialized with std::forward<T>(value)
.
The constructed proxy
object.
Throws any exception thrown by allocation or the constructor of T
.
The implementation of allocated-ptr
may vary depending on the definition of F
. Specifically, when F::constraints.max_size
and F::constraints.max_align
are not large enough to hold both a pointer to the allocated memory and a copy of the allocator, allocated-ptr
shall allocate additional storage for the allocator.
#include <array>
#include "proxy.h"
// By default, the maximum pointer size defined by pro::facade_builder
// is 2 * sizeof(void*). This value can be overridden by `restrict_layout`.
struct Any : pro::facade_builder::build {};
int main() {
// sizeof(std::array<int, 100>) is usually greater than 2 * sizeof(void*),
// calling allocate_proxy has no limitation to the size and alignment of the target
using Target = std::array<int, 100>;
pro::proxy<Any> p1 = pro::allocate_proxy<Any, Target>(std::allocator<Target>{});
}