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regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::container::allocator_traits
// In header: <boost/container/allocator_traits.hpp> template<typename Allocator> struct allocator_traits { // types typedef Allocator allocator_type; typedef allocator_type::value_type value_type; typedef unspecified pointer; typedef see_documentation const_pointer; typedef see_documentation reference; typedef see_documentation const_reference; typedef see_documentation void_pointer; typedef see_documentation const_void_pointer; typedef see_documentation difference_type; typedef see_documentation size_type; typedef see_documentation propagate_on_container_copy_assignment; typedef see_documentation propagate_on_container_move_assignment; typedef see_documentation propagate_on_container_swap; typedef see_documentation is_always_equal; typedef see_documentation is_partially_propagable; typedef see_documentation rebind_alloc; typedef allocator_traits< rebind_alloc< T > > rebind_traits; // member classes/structs/unions template<typename T> struct portable_rebind_alloc { // types typedef see_documentation type; }; // public static functions static pointer allocate(Allocator &, size_type); static void deallocate(Allocator &, pointer, size_type); static pointer allocate(Allocator &, size_type, const_void_pointer); template<typename T> static void destroy(Allocator &, T *) noexcept; static size_type max_size(const Allocator &) noexcept; static Allocator select_on_container_copy_construction(const Allocator &); template<typename T, class... Args> static void construct(Allocator &, T *, Args &&...); static bool storage_is_unpropagable(const Allocator &, pointer) noexcept; static bool equal(const Allocator &, const Allocator &) noexcept; };
The class template allocator_traits supplies a uniform interface to all allocator types. This class is a C++03-compatible implementation of std::allocator_traits
allocator_traits
public
typesAllocator::pointer if such a type exists; otherwise, value_type*
typedef see_documentation const_pointer;
Allocator::const_pointer if such a type exists ; otherwise, pointer_traits<pointer>::rebind<const
typedef see_documentation reference;
Non-standard extension Allocator::reference if such a type exists; otherwise, value_type&
typedef see_documentation const_reference;
Non-standard extension Allocator::const_reference if such a type exists ; otherwise, const value_type&
typedef see_documentation void_pointer;
Allocator::void_pointer if such a type exists ; otherwise, pointer_traits<pointer>::rebind<void>.
typedef see_documentation const_void_pointer;
Allocator::const_void_pointer if such a type exists ; otherwis e, pointer_traits<pointer>::rebind<const
typedef see_documentation difference_type;
Allocator::difference_type if such a type exists ; otherwise, pointer_traits<pointer>::difference_type.
typedef see_documentation size_type;
Allocator::size_type if such a type exists ; otherwise, make_unsigned<difference_type>::type
typedef see_documentation propagate_on_container_copy_assignment;
Allocator::propagate_on_container_copy_assignment if such a type exists, otherwise a type with an internal constant static boolean member value
== false.
typedef see_documentation propagate_on_container_move_assignment;
Allocator::propagate_on_container_move_assignment if such a type exists, otherwise a type with an internal constant static boolean member value
== false.
typedef see_documentation propagate_on_container_swap;
Allocator::propagate_on_container_swap if such a type exists, otherwise a type with an internal constant static boolean member value
== false.
typedef see_documentation is_always_equal;
Allocator::is_always_equal if such a type exists, otherwise a type with an internal constant static boolean member value
== is_empty<Allocator>::value
typedef see_documentation is_partially_propagable;
Allocator::is_partially_propagable if such a type exists, otherwise a type with an internal constant static boolean member value
== false Note: Non-standard extension used to implement small_vector_allocator
.
typedef see_documentation rebind_alloc;
Defines an allocator: Allocator::rebind<T>::other if such a type exists; otherwise, Allocator<T, Args> if Allocator is a class template instantiation of the form Allocator<U, Args>, where Args is zero or more type arguments ; otherwise, the instantiation of rebind_alloc is ill-formed.
In C++03 compilers rebind_alloc
is a struct derived from an allocator deduced by previously detailed rules.
typedef allocator_traits< rebind_alloc< T > > rebind_traits;
In C++03 compilers rebind_traits
is a struct derived from allocator_traits<OtherAlloc>
, where OtherAlloc
is the allocator deduced by rules explained in rebind_alloc
.
allocator_traits
public static functionsstatic pointer allocate(Allocator & a, size_type n);
Returns: a.allocate(n)
static void deallocate(Allocator & a, pointer p, size_type n);
Returns: a.deallocate(p, n)
Throws: Nothing
static pointer allocate(Allocator & a, size_type n, const_void_pointer p);
Effects: calls a.allocate(n, p)
if that call is well-formed; otherwise, invokes a.allocate(n)
template<typename T> static void destroy(Allocator & a, T * p) noexcept;
Effects: calls a.destroy(p)
if that call is well-formed; otherwise, invokes p->~T()
.
static size_type max_size(const Allocator & a) noexcept;
Returns: a.max_size()
if that expression is well-formed; otherwise, numeric_limits<size_type>::max()
.
static Allocator select_on_container_copy_construction(const Allocator & a);
Returns: a.select_on_container_copy_construction()
if that expression is well-formed; otherwise, a.
template<typename T, class... Args> static void construct(Allocator & a, T * p, Args &&... args);
Effects: calls a.construct(p, std::forward<Args>(args)...)
if that call is well-formed; otherwise, invokes ::new (static_cast<void*>(p)) T(std::forward<Args>(args)...)
static bool storage_is_unpropagable(const Allocator & a, pointer p) noexcept;
Returns: a.storage_is_unpropagable(p)
if is_partially_propagable::value is true; otherwise, false
.
static bool equal(const Allocator & a, const Allocator & b) noexcept;
Returns: true
if is_always_equal::value == true
, otherwise, a == b
.