bsl::allocator_traits

Synopsis

Declared in <bslma_allocatortraits.h>

template<class ALLOCATOR_TYPE>
struct allocator_traits;

Description

This class supports the complete interface of the C++11 allocator_traits class template, which provides a uniform mechanism for accessing nested types within, and operations on, any standard-conforming allocator. A specialization of this class template for bsl::allocator provides support for Bloomberg's bslma allocator model (see the bslma_bslallocator component for more details). In C++11 compilation environments, the construct methods forward to the allocator's construct method if such a method matching the (variable number of) specified constructor arguments exists; otherwise, the construct method falls back to invoking the constructor of the element type directly. In C++03 compilation environments, there is no reliable way to detect if the type provide a method that matches a (variable number of) specified arguments; therefore, we require that standard allocator types define construct methods taking a variable number of arguments in those environments. This implementation is not fully-standard-conforming in that it does not support deduce data types that are not specified in the allocator.

Type Aliases

Name	Description
`allocator_type`	This `typedef` is an alias to the (template parameter) `ALLOCATOR_TYPE`.
`const_pointer`	This `typedef` is an alias to `AllocatorTraits_ConstPointerType<ALLOCATOR_TYPE>::type`.
`const_void_pointer`	Const void pointer type for the allocator.
`difference_type`	This `typedef` is an alias to `AllocatorTraits_DifferenceType<ALLOCATOR_TYPE>::type`.
`is_always_equal`	`true_type` if two allocators always compare equal; else `false_type`.
`pointer`	This `typedef` is an alias to `AllocatorTraits_PointerType<ALLOCATOR_TYPE>::type`.
`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.
`rebind_alloc`	Rebind this allocator to the specified `ELEMENT_TYPE`.
`rebind_traits`	Rebind this allocator traits type to the specified `ELEMENT_TYPE`.
`size_type`	This `typedef` is an alias to `AllocatorTraits_SizeType<ALLOCATOR_TYPE>::type`.
`value_type`	This `typedef` is an alias to `ALLOCATOR_TYPE::value_type`.
`void_pointer`	This `typedef` is an alias to `AllocatorTraits_VoidPointerType<ALLOCATOR_TYPE>::type`.

Static Member Functions

Name	Description
`allocate`	`allocate` overloads
`construct`	Construct an `ELEMENT_TYPE` object at `elementAddr`.
`deallocate`	Deallocate the storage at `elementAddr` for `n` objects.
`destroy`	Destroy the `ELEMENT_TYPE` object at `elementAddr`.
`max_size`	Return the maximum number of objects `allocate` can return.
`select_on_container_copy_construction`	Return the allocator to use when copy-constructing a container.

Specializations

Name	Description
`allocator_traits<allocator<TYPE>>`	Specialization of `allocator_traits` for `bsl::allocator`.
`allocator_traits<std::allocator<ALLOCATOR_TYPE>>`	Specialization of `allocator_traits` that uses `std::allocator_traits`.
`allocator_traits<ALLOCATOR_TYPE*>`	Empty specialization of `allocator_traits` for pointer allocator types.

Derived Classes

Name	Description
`AllocatorUtil_Traits<t_MEMORY_RSRC*, t_TYPE>`	Traits for an allocator expressed as a pointer to a memory resource.