bsl::allocator_traits

Uniform interface to nested types and operations of any allocator.

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.

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 this allocator to the specified ELEMENT_TYPE.

rebind_traits

Rebind this allocator traits type to the specified ELEMENT_TYPE.

This typedef is an alias to AllocatorTraits_SizeType<ALLOCATOR_TYPE>::type.

This typedef is an alias to ALLOCATOR_TYPE::value_type.

This typedef is an alias to AllocatorTraits_VoidPointerType<ALLOCATOR_TYPE>::type.

Static Member Functions

Name

Description

allocate overloads

Construct an ELEMENT_TYPE object at elementAddr.

Deallocate the storage at elementAddr for n objects.

Destroy the ELEMENT_TYPE object at elementAddr.

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.

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