bsl::allocator_traits<std::allocator<ALLOCATOR_TYPE>>

Specialization of allocator_traits that uses std::allocator_traits.

Synopsis

Declared in <bslma_allocatortraits.h>

template<class ALLOCATOR_TYPE>
struct allocator_traits<std::allocator<ALLOCATOR_TYPE>>;

Description

Since C++17 many of the std::allocator members are deprecated (and removed in C++20). C++23 deprecates type name members and C++26 removes them. The clang compiler on Darwin warns about any mention of those names in C++17 so this header file was producing many warnings. The specialization below "disconnects" the allocator traits of std::allocator from our own implementation and so it avoids not only warnings but possible other hassles as the std::allocator interface is morphing.

Note that we are using the standard traits (in place of ours) only on C++17 or later compilers and not C++11 (when std::allocator_traits appeared). The reason for this is that our bsl::allocator_traits supports allocator_traits::is_always_equal from C++17 in a backwards compatible manner so we cannot use pre‐C++17 standard implementation that does not have that.

Type Aliases

Name

Description

Alias template that rebinds the allocator to ELEMENT_TYPE.

rebind_traits

allocator_traits for an allocator rebound to ELEMENT_TYPE.

Using Declarations

Name

Description

Allocate uninitialized storage for n objects, optionally using hint.

allocator_type

This typedef is an alias to std::allocator<ALLOCATOR_TYPE>.

const_pointer

This typedef is an alias to allocator_type::const_pointer.

const_void_pointer

This typedef is an alias to allocator_type::const_void_pointer.

Construct an object at the specified uninitialized address.

Deallocate the storage at p for n objects.

Destroy the object at the specified address.

difference_type

This typedef is an alias to allocator_type::difference_type.

is_always_equal

true_type if two allocators always compare equal; else false_type.

Return the maximum number of objects allocate can return.

This typedef is an alias to allocator_type::pointer.

propagate_on_container_copy_assignment

true_type if the allocator propagates on copy assignment.

propagate_on_container_move_assignment

true_type if the allocator propagates on move assignment.

propagate_on_container_swap

true_type if the allocator propagates on container swap.

select_on_container_copy_construction

Return the allocator to use when copy‐constructing a container.

This typedef is an alias to allocator_type::size_type.

This typedef is an alias to allocator_type::value_type.

This typedef is an alias to allocator_type::void_pointer.

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