STD::ALLOCATOR_TRAITS(3cxx)

🌸 NAME 🌸

okay bestie, this is std::allocator_traits< _Alloc > — Uniform interface to all allocator types. ✨ it's from the 3cxx manual, and it's lowkey iconic 🫶

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✨ SYNOPSIS ✨

#include <memory>

Inherits __allocator_traits_base.

Inherited by __gnu_cxx::__alloc_traits< _Tp_alloc_type >, and __gnu_cxx::__alloc_traits< _Alloc, typename >.

💅 Public Types 💅

• typedef _Alloc allocator_type — the allocator type itself, no notes 💅
• using const_pointer = typename _Ptr< __c_pointer, const value_type >::type — the allocator's const pointer type.
• using const_void_pointer = typename _Ptr< __cv_pointer, const void >::type — the allocator's const void pointer type.
• using difference_type = typename _Diff< _Alloc, pointer >::type — the allocator's difference type.
• using is_always_equal = typename __detected_or_t< is_empty< _Alloc >, __equal, _Alloc >::type — whether all instances of the allocator type compare equal 🫶
• using pointer = __detected_or_t< value_type *, __pointer, _Alloc > — the allocator's pointer type.
• using propagate_on_container_copy_assignment = __detected_or_t< false_type, __pocca, _Alloc > — how the allocator is propagated on copy assignment.
• using propagate_on_container_move_assignment = __detected_or_t< false_type, __pocma, _Alloc > — how the allocator is propagated on move assignment.
• using propagate_on_container_swap = __detected_or_t< false_type, __pocs, _Alloc > — how the allocator is propagated on swap.
• template<typename _Tp > using rebind_alloc = __alloc_rebind< _Alloc, _Tp > — rebind magic ✨
• template<typename _Tp > using rebind_traits = allocator_traits< rebind_alloc< _Tp > > — more rebind magic ✨
• using size_type = typename _Size< _Alloc, difference_type >::type — the allocator's size type.
• typedef _Alloc::value_type value_type — the allocated type.
• using void_pointer = typename _Ptr< __v_pointer, void >::type — the allocator's void pointer type.

🛠️ Static Public Member Functions 🛠️

• static constexpr pointer allocate (_Alloc &__a, size_type __n) — allocate memory.
• static constexpr pointer allocate (_Alloc &__a, size_type __n, const_void_pointer __hint) — allocate memory.
• template<typename _Tp , typename... _Args> static constexpr auto construct (_Alloc &__a, _Tp *__p, _Args &&... __args) noexcept(noexcept(_S_construct(__a, __p, std::forward< _Args >(__args)...))) -> decltype(_S_construct(__a, __p, std::forward< _Args >(__args)...)) — construct an object of type _Tp
• static constexpr void deallocate (_Alloc &__a, pointer __p, size_type __n) — deallocate memory.
• template<typename _Tp > static constexpr void destroy (_Alloc &__a, _Tp *__p) noexcept(noexcept(_S_destroy(__a, __p, 0))) — destroy an object of type _Tp.
• static constexpr size_type max_size (const _Alloc &__a) noexcept — the maximum supported allocation size.
• static constexpr _Alloc select_on_container_copy_construction (const _Alloc &__rhs) — obtain an allocator to use when copying a container.

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💖 Detailed Description 💖

template<typename _Alloc>
    struct std::allocator_traits< _Alloc >

Uniform interface to all allocator types. it's giving "one trait struct to rule all allocators" energy 👑

Since: C++11

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🎀 Member Typedef Documentation 🎀

allocator_type

template<typename _Alloc > typedef _Alloc std::allocator_traits< _Alloc >::allocator_type

The allocator type. That's it, that's the tweet 💅

const_pointer

template<typename _Alloc > using std::allocator_traits< _Alloc >::const_pointer =  typename _Ptr<__c_pointer, const value_type>::type

The allocator's const pointer type. It's Alloc::const_pointer if that type exists, otherwise it falls back to pointer_traits<pointer>::rebind<const value_type>.

const_void_pointer

template<typename _Alloc > using std::allocator_traits< _Alloc >::const_void_pointer =  typename _Ptr<__cv_pointer, const void>::type

The allocator's const void pointer type. It's Alloc::const_void_pointer if that type exists, otherwise it falls back to pointer_traits<pointer>::rebind<const void>.

difference_type

template<typename _Alloc > using std::allocator_traits< _Alloc >::difference_type =  typename _Diff<_Alloc, pointer>::type

The allocator's difference type. It's Alloc::difference_type if that type exists, otherwise it falls back to pointer_traits<pointer>::difference_type.

is_always_equal

template<typename _Alloc > using std::allocator_traits< _Alloc >::is_always_equal =  typename __detected_or_t<is_empty<_Alloc>, __equal, _Alloc>::type

Whether all instances of the allocator type compare equal. It's Alloc::is_always_equal if that type exists, otherwise it falls back to is_empty<Alloc>::type.

pointer

template<typename _Alloc > using std::allocator_traits< _Alloc >::pointer = __detected_or_t<value_type*, __pointer, _Alloc>

The allocator's pointer type. It's Alloc::pointer if that type exists, otherwise it falls back to value_type*.

propagate_on_container_copy_assignment

template<typename _Alloc > using std::allocator_traits< _Alloc >::propagate_on_container_copy_assignment =  __detected_or_t<false_type, __pocca, _Alloc>

How the allocator is propagated on copy assignment. It's Alloc::propagate_on_container_copy_assignment if that type exists, otherwise it falls back to false_type.

propagate_on_container_move_assignment

template<typename _Alloc > using std::allocator_traits< _Alloc >::propagate_on_container_move_assignment =  __detected_or_t<false_type, __pocma, _Alloc>

How the allocator is propagated on move assignment. It's Alloc::propagate_on_container_move_assignment if that type exists, otherwise it falls back to false_type.

propagate_on_container_swap

template<typename _Alloc > using std::allocator_traits< _Alloc >::propagate_on_container_swap =  __detected_or_t<false_type, __pocs, _Alloc>

How the allocator is propagated on swap. It's Alloc::propagate_on_container_swap if that type exists, otherwise it falls back to false_type.

size_type

template<typename _Alloc > using std::allocator_traits< _Alloc >::size_type =  typename _Size<_Alloc, difference_type>::type

The allocator's size type. It's Alloc::size_type if that type exists, otherwise it falls back to make_unsigned<difference_type>::type.

value_type

template<typename _Alloc > typedef _Alloc::value_type std::allocator_traits< _Alloc >::value_type

The allocated type. periodt 🎀

void_pointer

template<typename _Alloc > using std::allocator_traits< _Alloc >::void_pointer =  typename _Ptr<__v_pointer, void>::type

The allocator's void pointer type. It's Alloc::void_pointer if that type exists, otherwise it falls back to pointer_traits<pointer>::rebind<void>.

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🔥 Member Function Documentation 🔥

allocate

template<typename _Alloc > static constexpr pointer std::allocator_traits< _Alloc >::allocate (_Alloc & __a, size_type __n) [inline],  [static],  [constexpr]

Allocate memory.

Parameters:

• __a — an allocator.
• __n — the number of objects to allocate space for.

Calls a.allocate(n).

allocate with hint

template<typename _Alloc > static constexpr pointer std::allocator_traits< _Alloc >::allocate (_Alloc & __a, size_type __n, const_void_pointer __hint) [inline],  [static],  [constexpr]

Allocate memory.

Parameters:

• __a — an allocator.
• __n — the number of objects to allocate space for.
• __hint — aid to locality.

Returns: memory of suitable size and alignment for n objects of type value_type.

Returns a.allocate(n, hint) if that expression is well-formed, otherwise returns a.allocate(n).

construct

template<typename _Alloc > template<typename _Tp , typename... _Args> static constexpr auto std::allocator_traits< _Alloc >::construct (_Alloc & __a, _Tp * __p, _Args &&... __args) -> decltype(_S_construct(__a, __p, std::forward<_Args>(__args)...))
      [inline],  [static],  [constexpr],  [noexcept]"

Construct an object of type _Tp.

Parameters:

• __a — an allocator.
• __p — pointer to memory of suitable size and alignment for Tp.
• __args — constructor arguments.

Calls __a.construct(__p, std::forward<Args>(__args)...) if that expression is well-formed, otherwise uses placement-new to construct an object of type _Tp at location __p from the arguments __args....

deallocate

template<typename _Alloc > static constexpr void std::allocator_traits< _Alloc >::deallocate (_Alloc & __a, pointer __p, size_type __n) [inline],  [static],  [constexpr]

Deallocate memory.

Parameters:

• __a — an allocator.
• __p — pointer to the memory to deallocate.
• __n — the number of objects space was allocated for.

Calls a.deallocate(p, n).

destroy

template<typename _Alloc > template<typename _Tp > static constexpr void std::allocator_traits< _Alloc >::destroy (_Alloc & __a, _Tp * __p) [inline],  [static],  [constexpr],  [noexcept]

Destroy an object of type _Tp.

Parameters:

• __a — an allocator.
• __p — pointer to the object to destroy.

Calls __a.destroy(__p) if that expression is well-formed, otherwise calls __p->~_Tp().

max_size

template<typename _Alloc > static constexpr size_type std::allocator_traits< _Alloc >::max_size (const _Alloc & __a) [inline],  [static],  [constexpr],  [noexcept]

The maximum supported allocation size.

Parameters:

• __a — an allocator.

Returns __a.max_size() or numeric_limits<size_type>::max().

Returns __a.max_size() if that expression is well-formed, otherwise returns numeric_limits<size_type>::max().

select_on_container_copy_construction

template<typename _Alloc > static constexpr _Alloc std::allocator_traits< _Alloc >::select_on_container_copy_construction (const _Alloc & __rhs) [inline],  [static],  [constexpr]

Obtain an allocator to use when copying a container.

Parameters:

• __rhs — an allocator.

Returns __rhs.select_on_container_copy_construction() or __rhs.

Returns __rhs.select_on_container_copy_construction() if that expression is well-formed, otherwise returns __rhs.

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📜 Author 📜

Generated automatically by Doxygen for libstdc++ from the source code.

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okay that's the whole page, bestie 🫶 the footer literally reads libstdcstd::allocator_traits< _Alloc >(3cxx) — and there's no date on it, so I'm not inventing one. no cap, that's the real source/version vibe 💅