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// Allocator traits -*- C++ -*-
// Copyright (C) 2011-2022 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file bits/alloc_traits.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{memory}
*/
#ifndef _ALLOC_TRAITS_H
#define _ALLOC_TRAITS_H 1
#include <bits/stl_construct.h>
#include <bits/memoryfwd.h>
#if __cplusplus >= 201103L
# include <bits/ptr_traits.h>
# include <ext/numeric_traits.h>
# if _GLIBCXX_HOSTED
# include <bits/allocator.h>
# endif
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
#if __cplusplus >= 201103L
#define __cpp_lib_allocator_traits_is_always_equal 201411L
/// @cond undocumented
struct __allocator_traits_base
{
template<typename _Tp, typename _Up, typename = void>
struct __rebind : __replace_first_arg<_Tp, _Up> { };
template<typename _Tp, typename _Up>
struct __rebind<_Tp, _Up,
__void_t<typename _Tp::template rebind<_Up>::other>>
{ using type = typename _Tp::template rebind<_Up>::other; };
protected:
template<typename _Tp>
using __pointer = typename _Tp::pointer;
template<typename _Tp>
using __c_pointer = typename _Tp::const_pointer;
template<typename _Tp>
using __v_pointer = typename _Tp::void_pointer;
template<typename _Tp>
using __cv_pointer = typename _Tp::const_void_pointer;
template<typename _Tp>
using __pocca = typename _Tp::propagate_on_container_copy_assignment;
template<typename _Tp>
using __pocma = typename _Tp::propagate_on_container_move_assignment;
template<typename _Tp>
using __pocs = typename _Tp::propagate_on_container_swap;
template<typename _Tp>
using __equal = __type_identity<typename _Tp::is_always_equal>;
};
template<typename _Alloc, typename _Up>
using __alloc_rebind
= typename __allocator_traits_base::template __rebind<_Alloc, _Up>::type;
/// @endcond
/**
* @brief Uniform interface to all allocator types.
* @headerfile memory
* @ingroup allocators
* @since C++11
*/
template<typename _Alloc>
struct allocator_traits : __allocator_traits_base
{
/// The allocator type
typedef _Alloc allocator_type;
/// The allocated type
typedef typename _Alloc::value_type value_type;
/**
* @brief The allocator's pointer type.
*
* @c Alloc::pointer if that type exists, otherwise @c value_type*
*/
using pointer = __detected_or_t<value_type*, __pointer, _Alloc>;
private:
// Select _Func<_Alloc> or pointer_traits<pointer>::rebind<_Tp>
template<template<typename> class _Func, typename _Tp, typename = void>
struct _Ptr
{
using type = typename pointer_traits<pointer>::template rebind<_Tp>;
};
template<template<typename> class _Func, typename _Tp>
struct _Ptr<_Func, _Tp, __void_t<_Func<_Alloc>>>
{
using type = _Func<_Alloc>;
};
// Select _A2::difference_type or pointer_traits<_Ptr>::difference_type
template<typename _A2, typename _PtrT, typename = void>
struct _Diff
{ using type = typename pointer_traits<_PtrT>::difference_type; };
template<typename _A2, typename _PtrT>
struct _Diff<_A2, _PtrT, __void_t<typename _A2::difference_type>>
{ using type = typename _A2::difference_type; };
// Select _A2::size_type or make_unsigned<_DiffT>::type
template<typename _A2, typename _DiffT, typename = void>
struct _Size : make_unsigned<_DiffT> { };
template<typename _A2, typename _DiffT>
struct _Size<_A2, _DiffT, __void_t<typename _A2::size_type>>
{ using type = typename _A2::size_type; };
public:
/**
* @brief The allocator's const pointer type.
*
* @c Alloc::const_pointer if that type exists, otherwise
* <tt> pointer_traits<pointer>::rebind<const value_type> </tt>
*/
using const_pointer = typename _Ptr<__c_pointer, const value_type>::type;
/**
* @brief The allocator's void pointer type.
*
* @c Alloc::void_pointer if that type exists, otherwise
* <tt> pointer_traits<pointer>::rebind<void> </tt>
*/
using void_pointer = typename _Ptr<__v_pointer, void>::type;
/**
* @brief The allocator's const void pointer type.
*
* @c Alloc::const_void_pointer if that type exists, otherwise
* <tt> pointer_traits<pointer>::rebind<const void> </tt>
*/
using const_void_pointer = typename _Ptr<__cv_pointer, const void>::type;
/**
* @brief The allocator's difference type
*
* @c Alloc::difference_type if that type exists, otherwise
* <tt> pointer_traits<pointer>::difference_type </tt>
*/
using difference_type = typename _Diff<_Alloc, pointer>::type;
/**
* @brief The allocator's size type
*
* @c Alloc::size_type if that type exists, otherwise
* <tt> make_unsigned<difference_type>::type </tt>
*/
using size_type = typename _Size<_Alloc, difference_type>::type;
/**
* @brief How the allocator is propagated on copy assignment
*
* @c Alloc::propagate_on_container_copy_assignment if that type exists,
* otherwise @c false_type
*/
using propagate_on_container_copy_assignment
= __detected_or_t<false_type, __pocca, _Alloc>;
/**
* @brief How the allocator is propagated on move assignment
*
* @c Alloc::propagate_on_container_move_assignment if that type exists,
* otherwise @c false_type
*/
using propagate_on_container_move_assignment
= __detected_or_t<false_type, __pocma, _Alloc>;
/**
* @brief How the allocator is propagated on swap
*
* @c Alloc::propagate_on_container_swap if that type exists,
* otherwise @c false_type
*/
using propagate_on_container_swap
= __detected_or_t<false_type, __pocs, _Alloc>;
/**
* @brief Whether all instances of the allocator type compare equal.
*
* @c Alloc::is_always_equal if that type exists,
* otherwise @c is_empty<Alloc>::type
*/
using is_always_equal
= typename __detected_or_t<is_empty<_Alloc>, __equal, _Alloc>::type;
template<typename _Tp>
using rebind_alloc = __alloc_rebind<_Alloc, _Tp>;
template<typename _Tp>
using rebind_traits = allocator_traits<rebind_alloc<_Tp>>;
private:
template<typename _Alloc2>
static constexpr auto
_S_allocate(_Alloc2& __a, size_type __n, const_void_pointer __hint, int)
-> decltype(__a.allocate(__n, __hint))
{ return __a.allocate(__n, __hint); }
template<typename _Alloc2>
static constexpr pointer
_S_allocate(_Alloc2& __a, size_type __n, const_void_pointer, ...)
{ return __a.allocate(__n); }
template<typename _Tp, typename... _Args>
struct __construct_helper
{
template<typename _Alloc2,
typename = decltype(std::declval<_Alloc2*>()->construct(
std::declval<_Tp*>(), std::declval<_Args>()...))>
static true_type __test(int);
template<typename>
static false_type __test(...);
using type = decltype(__test<_Alloc>(0));
};
template<typename _Tp, typename... _Args>
using __has_construct
= typename __construct_helper<_Tp, _Args...>::type;
template<typename _Tp, typename... _Args>
static _GLIBCXX14_CONSTEXPR _Require<__has_construct<_Tp, _Args...>>
_S_construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
noexcept(noexcept(__a.construct(__p, std::forward<_Args>(__args)...)))
{ __a.construct(__p, std::forward<_Args>(__args)...); }
template<typename _Tp, typename... _Args>
static _GLIBCXX14_CONSTEXPR
_Require<__and_<__not_<__has_construct<_Tp, _Args...>>,
is_constructible<_Tp, _Args...>>>
_S_construct(_Alloc&, _Tp* __p, _Args&&... __args)
noexcept(std::is_nothrow_constructible<_Tp, _Args...>::value)
{
#if __cplusplus <= 201703L
::new((void*)__p) _Tp(std::forward<_Args>(__args)...);
#else
std::construct_at(__p, std::forward<_Args>(__args)...);
#endif
}
template<typename _Alloc2, typename _Tp>
static _GLIBCXX14_CONSTEXPR auto
_S_destroy(_Alloc2& __a, _Tp* __p, int)
noexcept(noexcept(__a.destroy(__p)))
-> decltype(__a.destroy(__p))
{ __a.destroy(__p); }
template<typename _Alloc2, typename _Tp>
static _GLIBCXX14_CONSTEXPR void
_S_destroy(_Alloc2&, _Tp* __p, ...)
noexcept(std::is_nothrow_destructible<_Tp>::value)
{ std::_Destroy(__p); }
template<typename _Alloc2>
static constexpr auto
_S_max_size(_Alloc2& __a, int)
-> decltype(__a.max_size())
{ return __a.max_size(); }
template<typename _Alloc2>
static constexpr size_type
_S_max_size(_Alloc2&, ...)
{
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2466. allocator_traits::max_size() default behavior is incorrect
return __gnu_cxx::__numeric_traits<size_type>::__max
/ sizeof(value_type);
}
template<typename _Alloc2>
static constexpr auto
_S_select(_Alloc2& __a, int)
-> decltype(__a.select_on_container_copy_construction())
{ return __a.select_on_container_copy_construction(); }
template<typename _Alloc2>
static constexpr _Alloc2
_S_select(_Alloc2& __a, ...)
{ return __a; }
public:
/**
* @brief Allocate memory.
* @param __a An allocator.
* @param __n The number of objects to allocate space for.
*
* Calls @c a.allocate(n)
*/
_GLIBCXX_NODISCARD static _GLIBCXX20_CONSTEXPR pointer
allocate(_Alloc& __a, size_type __n)
{ return __a.allocate(__n); }
/**
* @brief Allocate memory.
* @param __a An allocator.
* @param __n The number of objects to allocate space for.
* @param __hint Aid to locality.
* @return Memory of suitable size and alignment for @a n objects
* of type @c value_type
*
* Returns <tt> a.allocate(n, hint) </tt> if that expression is
* well-formed, otherwise returns @c a.allocate(n)
*/
_GLIBCXX_NODISCARD static _GLIBCXX20_CONSTEXPR pointer
allocate(_Alloc& __a, size_type __n, const_void_pointer __hint)
{ return _S_allocate(__a, __n, __hint, 0); }
/**
* @brief Deallocate memory.
* @param __a An allocator.
* @param __p Pointer to the memory to deallocate.
* @param __n The number of objects space was allocated for.
*
* Calls <tt> a.deallocate(p, n) </tt>
*/
static _GLIBCXX20_CONSTEXPR void
deallocate(_Alloc& __a, pointer __p, size_type __n)
{ __a.deallocate(__p, __n); }
/**
* @brief Construct an object of type `_Tp`
* @param __a An allocator.
* @param __p Pointer to memory of suitable size and alignment for Tp
* @param __args Constructor arguments.
*
* Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt>
* if that expression is well-formed, otherwise uses placement-new
* to construct an object of type @a _Tp at location @a __p from the
* arguments @a __args...
*/
template<typename _Tp, typename... _Args>
static _GLIBCXX20_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)...))
{ _S_construct(__a, __p, std::forward<_Args>(__args)...); }
/**
* @brief Destroy an object of type @a _Tp
* @param __a An allocator.
* @param __p Pointer to the object to destroy
*
* Calls @c __a.destroy(__p) if that expression is well-formed,
* otherwise calls @c __p->~_Tp()
*/
template<typename _Tp>
static _GLIBCXX20_CONSTEXPR void
destroy(_Alloc& __a, _Tp* __p)
noexcept(noexcept(_S_destroy(__a, __p, 0)))
{ _S_destroy(__a, __p, 0); }
/**
* @brief The maximum supported allocation size
* @param __a An allocator.
* @return @c __a.max_size() or @c numeric_limits<size_type>::max()
*
* Returns @c __a.max_size() if that expression is well-formed,
* otherwise returns @c numeric_limits<size_type>::max()
*/
static _GLIBCXX20_CONSTEXPR size_type
max_size(const _Alloc& __a) noexcept
{ return _S_max_size(__a, 0); }
/**
* @brief Obtain an allocator to use when copying a container.
* @param __rhs An allocator.
* @return @c __rhs.select_on_container_copy_construction() or @a __rhs
*
* Returns @c __rhs.select_on_container_copy_construction() if that
* expression is well-formed, otherwise returns @a __rhs
*/
static _GLIBCXX20_CONSTEXPR _Alloc
select_on_container_copy_construction(const _Alloc& __rhs)
{ return _S_select(__rhs, 0); }
};
#if _GLIBCXX_HOSTED
#if __cplusplus > 201703L
# define __cpp_lib_constexpr_dynamic_alloc 201907L
#endif
/// Partial specialization for std::allocator.
template<typename _Tp>
struct allocator_traits<allocator<_Tp>>
{
/// The allocator type
using allocator_type = allocator<_Tp>;
/// The allocated type
using value_type = _Tp;
/// The allocator's pointer type.
using pointer = _Tp*;
/// The allocator's const pointer type.
using const_pointer = const _Tp*;
/// The allocator's void pointer type.
using void_pointer = void*;
/// The allocator's const void pointer type.
using const_void_pointer = const void*;
/// The allocator's difference type
using difference_type = std::ptrdiff_t;
/// The allocator's size type
using size_type = std::size_t;
/// How the allocator is propagated on copy assignment
using propagate_on_container_copy_assignment = false_type;
/// How the allocator is propagated on move assignment
using propagate_on_container_move_assignment = true_type;
/// How the allocator is propagated on swap
using propagate_on_container_swap = false_type;
/// Whether all instances of the allocator type compare equal.
using is_always_equal = true_type;
template<typename _Up>
using rebind_alloc = allocator<_Up>;
template<typename _Up>
using rebind_traits = allocator_traits<allocator<_Up>>;
/**
* @brief Allocate memory.
* @param __a An allocator.
* @param __n The number of objects to allocate space for.
*
* Calls @c a.allocate(n)
*/
[[__nodiscard__,__gnu__::__always_inline__]]
static _GLIBCXX20_CONSTEXPR pointer
allocate(allocator_type& __a, size_type __n)
{ return __a.allocate(__n); }
/**
* @brief Allocate memory.
* @param __a An allocator.
* @param __n The number of objects to allocate space for.
* @param __hint Aid to locality.
* @return Memory of suitable size and alignment for @a n objects
* of type @c value_type
*
* Returns <tt> a.allocate(n, hint) </tt>
*/
[[__nodiscard__,__gnu__::__always_inline__]]
static _GLIBCXX20_CONSTEXPR pointer
allocate(allocator_type& __a, size_type __n, const_void_pointer __hint)
{
#if __cplusplus <= 201703L
return __a.allocate(__n, __hint);
#else
return __a.allocate(__n);
#endif
}
/**
* @brief Deallocate memory.
* @param __a An allocator.
* @param __p Pointer to the memory to deallocate.
* @param __n The number of objects space was allocated for.
*
* Calls <tt> a.deallocate(p, n) </tt>
*/
[[__gnu__::__always_inline__]]
static _GLIBCXX20_CONSTEXPR void
deallocate(allocator_type& __a, pointer __p, size_type __n)
{ __a.deallocate(__p, __n); }
/**
* @brief Construct an object of type `_Up`
* @param __a An allocator.
* @param __p Pointer to memory of suitable size and alignment for
* an object of type `_Up`.
* @param __args Constructor arguments.
*
* Calls `__a.construct(__p, std::forward<_Args>(__args)...)`
* in C++11, C++14 and C++17. Changed in C++20 to call
* `std::construct_at(__p, std::forward<_Args>(__args)...)` instead.
*/
template<typename _Up, typename... _Args>
[[__gnu__::__always_inline__]]
static _GLIBCXX20_CONSTEXPR void
construct(allocator_type& __a __attribute__((__unused__)), _Up* __p,
_Args&&... __args)
noexcept(std::is_nothrow_constructible<_Up, _Args...>::value)
{
#if __cplusplus <= 201703L
__a.construct(__p, std::forward<_Args>(__args)...);
#else
std::construct_at(__p, std::forward<_Args>(__args)...);
#endif
}
/**
* @brief Destroy an object of type @a _Up
* @param __a An allocator.
* @param __p Pointer to the object to destroy
*
* Calls @c __a.destroy(__p).
*/
template<typename _Up>
[[__gnu__::__always_inline__]]
static _GLIBCXX20_CONSTEXPR void
destroy(allocator_type& __a __attribute__((__unused__)), _Up* __p)
noexcept(is_nothrow_destructible<_Up>::value)
{
#if __cplusplus <= 201703L
__a.destroy(__p);
#else
std::destroy_at(__p);
#endif
}
/**
* @brief The maximum supported allocation size
* @param __a An allocator.
* @return @c __a.max_size()
*/
[[__gnu__::__always_inline__]]
static _GLIBCXX20_CONSTEXPR size_type
max_size(const allocator_type& __a __attribute__((__unused__))) noexcept
{
#if __cplusplus <= 201703L
return __a.max_size();
#else
return size_t(-1) / sizeof(value_type);
#endif
}
/**
* @brief Obtain an allocator to use when copying a container.
* @param __rhs An allocator.
* @return @c __rhs
*/
[[__gnu__::__always_inline__]]
static _GLIBCXX20_CONSTEXPR allocator_type
select_on_container_copy_construction(const allocator_type& __rhs)
{ return __rhs; }
};
/// Explicit specialization for std::allocator<void>.
template<>
struct allocator_traits<allocator<void>>
{
/// The allocator type
using allocator_type = allocator<void>;
/// The allocated type
using value_type = void;
/// The allocator's pointer type.
using pointer = void*;
/// The allocator's const pointer type.
using const_pointer = const void*;
/// The allocator's void pointer type.
using void_pointer = void*;
/// The allocator's const void pointer type.
using const_void_pointer = const void*;
/// The allocator's difference type
using difference_type = std::ptrdiff_t;
/// The allocator's size type
using size_type = std::size_t;
/// How the allocator is propagated on copy assignment
using propagate_on_container_copy_assignment = false_type;
/// How the allocator is propagated on move assignment
using propagate_on_container_move_assignment = true_type;
/// How the allocator is propagated on swap
using propagate_on_container_swap = false_type;
/// Whether all instances of the allocator type compare equal.
using is_always_equal = true_type;
template<typename _Up>
using rebind_alloc = allocator<_Up>;
template<typename _Up>
using rebind_traits = allocator_traits<allocator<_Up>>;
/// allocate is ill-formed for allocator<void>
static void*
allocate(allocator_type&, size_type, const void* = nullptr) = delete;
/// deallocate is ill-formed for allocator<void>
static void
deallocate(allocator_type&, void*, size_type) = delete;
/**
* @brief Construct an object of type `_Up`
* @param __a An allocator.
* @param __p Pointer to memory of suitable size and alignment for
* an object of type `_Up`.
* @param __args Constructor arguments.
*
* Calls `__a.construct(__p, std::forward<_Args>(__args)...)`
* in C++11, C++14 and C++17. Changed in C++20 to call
* `std::construct_at(__p, std::forward<_Args>(__args)...)` instead.
*/
template<typename _Up, typename... _Args>
[[__gnu__::__always_inline__]]
static _GLIBCXX20_CONSTEXPR void
construct(allocator_type&, _Up* __p, _Args&&... __args)
noexcept(std::is_nothrow_constructible<_Up, _Args...>::value)
{ std::_Construct(__p, std::forward<_Args>(__args)...); }
/**
* @brief Destroy an object of type `_Up`
* @param __a An allocator.
* @param __p Pointer to the object to destroy
*
* Invokes the destructor for `*__p`.
*/
template<typename _Up>
[[__gnu__::__always_inline__]]
static _GLIBCXX20_CONSTEXPR void
destroy(allocator_type&, _Up* __p)
noexcept(is_nothrow_destructible<_Up>::value)
{ std::_Destroy(__p); }
/// max_size is ill-formed for allocator<void>
static size_type
max_size(const allocator_type&) = delete;
/**
* @brief Obtain an allocator to use when copying a container.
* @param __rhs An allocator.
* @return `__rhs`
*/
[[__gnu__::__always_inline__]]
static _GLIBCXX20_CONSTEXPR allocator_type
select_on_container_copy_construction(const allocator_type& __rhs)
{ return __rhs; }
};
#endif
/// @cond undocumented
#if __cplusplus < 201703L
template<typename _Alloc>
[[__gnu__::__always_inline__]]
inline void
__do_alloc_on_copy(_Alloc& __one, const _Alloc& __two, true_type)
{ __one = __two; }
template<typename _Alloc>
[[__gnu__::__always_inline__]]
inline void
__do_alloc_on_copy(_Alloc&, const _Alloc&, false_type)
{ }
#endif
template<typename _Alloc>
[[__gnu__::__always_inline__]]
_GLIBCXX14_CONSTEXPR inline void
__alloc_on_copy(_Alloc& __one, const _Alloc& __two)
{
using __traits = allocator_traits<_Alloc>;
using __pocca =
typename __traits::propagate_on_container_copy_assignment::type;
#if __cplusplus >= 201703L
if constexpr (__pocca::value)
__one = __two;
#else
__do_alloc_on_copy(__one, __two, __pocca());
#endif
}
template<typename _Alloc>
[[__gnu__::__always_inline__]]
constexpr _Alloc
__alloc_on_copy(const _Alloc& __a)
{
typedef allocator_traits<_Alloc> __traits;
return __traits::select_on_container_copy_construction(__a);
}
#if __cplusplus < 201703L
template<typename _Alloc>
[[__gnu__::__always_inline__]]
inline void __do_alloc_on_move(_Alloc& __one, _Alloc& __two, true_type)
{ __one = std::move(__two); }
template<typename _Alloc>
[[__gnu__::__always_inline__]]
inline void __do_alloc_on_move(_Alloc&, _Alloc&, false_type)
{ }
#endif
template<typename _Alloc>
[[__gnu__::__always_inline__]]
_GLIBCXX14_CONSTEXPR inline void
__alloc_on_move(_Alloc& __one, _Alloc& __two)
{
using __traits = allocator_traits<_Alloc>;
using __pocma
= typename __traits::propagate_on_container_move_assignment::type;
#if __cplusplus >= 201703L
if constexpr (__pocma::value)
__one = std::move(__two);
#else
__do_alloc_on_move(__one, __two, __pocma());
#endif
}
#if __cplusplus < 201703L
template<typename _Alloc>
[[__gnu__::__always_inline__]]
inline void __do_alloc_on_swap(_Alloc& __one, _Alloc& __two, true_type)
{
using std::swap;
swap(__one, __two);
}
template<typename _Alloc>
[[__gnu__::__always_inline__]]
inline void __do_alloc_on_swap(_Alloc&, _Alloc&, false_type)
{ }
#endif
template<typename _Alloc>
[[__gnu__::__always_inline__]]
_GLIBCXX14_CONSTEXPR inline void
__alloc_on_swap(_Alloc& __one, _Alloc& __two)
{
using __traits = allocator_traits<_Alloc>;
using __pocs = typename __traits::propagate_on_container_swap::type;
#if __cplusplus >= 201703L
if constexpr (__pocs::value)
{
using std::swap;
swap(__one, __two);
}
#else
__do_alloc_on_swap(__one, __two, __pocs());
#endif
}
template<typename _Alloc, typename _Tp,
typename _ValueT = __remove_cvref_t<typename _Alloc::value_type>,
typename = void>
struct __is_alloc_insertable_impl
: false_type
{ };
template<typename _Alloc, typename _Tp, typename _ValueT>
struct __is_alloc_insertable_impl<_Alloc, _Tp, _ValueT,
__void_t<decltype(allocator_traits<_Alloc>::construct(
std::declval<_Alloc&>(), std::declval<_ValueT*>(),
std::declval<_Tp>()))>>
: true_type
{ };
// true if _Alloc::value_type is CopyInsertable into containers using _Alloc
// (might be wrong if _Alloc::construct exists but is not constrained,
// i.e. actually trying to use it would still be invalid. Use with caution.)
template<typename _Alloc>
struct __is_copy_insertable
: __is_alloc_insertable_impl<_Alloc,
typename _Alloc::value_type const&>::type
{ };
#if _GLIBCXX_HOSTED
// std::allocator<_Tp> just requires CopyConstructible
template<typename _Tp>
struct __is_copy_insertable<allocator<_Tp>>
: is_copy_constructible<_Tp>
{ };
#endif
// true if _Alloc::value_type is MoveInsertable into containers using _Alloc
// (might be wrong if _Alloc::construct exists but is not constrained,
// i.e. actually trying to use it would still be invalid. Use with caution.)
template<typename _Alloc>
struct __is_move_insertable
: __is_alloc_insertable_impl<_Alloc, typename _Alloc::value_type>::type
{ };
#if _GLIBCXX_HOSTED
// std::allocator<_Tp> just requires MoveConstructible
template<typename _Tp>
struct __is_move_insertable<allocator<_Tp>>
: is_move_constructible<_Tp>
{ };
#endif
// Trait to detect Allocator-like types.
template<typename _Alloc, typename = void>
struct __is_allocator : false_type { };
template<typename _Alloc>
struct __is_allocator<_Alloc,
__void_t<typename _Alloc::value_type,
decltype(std::declval<_Alloc&>().allocate(size_t{}))>>
: true_type { };
template<typename _Alloc>
using _RequireAllocator
= typename enable_if<__is_allocator<_Alloc>::value, _Alloc>::type;
template<typename _Alloc>
using _RequireNotAllocator
= typename enable_if<!__is_allocator<_Alloc>::value, _Alloc>::type;
#if __cpp_concepts >= 201907L
template<typename _Alloc>
concept __allocator_like = requires (_Alloc& __a) {
typename _Alloc::value_type;
__a.deallocate(__a.allocate(1u), 1u);
};
#endif
/// @endcond
#endif // C++11
/// @cond undocumented
// To implement Option 3 of DR 431.
template<typename _Alloc, bool = __is_empty(_Alloc)>
struct __alloc_swap
{ static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } };
template<typename _Alloc>
struct __alloc_swap<_Alloc, false>
{
static void
_S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
{
// Precondition: swappable allocators.
if (__one != __two)
swap(__one, __two);
}
};
#if __cplusplus >= 201103L
template<typename _Tp, bool
= __or_<is_copy_constructible<typename _Tp::value_type>,
is_nothrow_move_constructible<typename _Tp::value_type>>::value>
struct __shrink_to_fit_aux
{ static bool _S_do_it(_Tp&) noexcept { return false; } };
template<typename _Tp>
struct __shrink_to_fit_aux<_Tp, true>
{
_GLIBCXX20_CONSTEXPR
static bool
_S_do_it(_Tp& __c) noexcept
{
#if __cpp_exceptions
try
{
_Tp(__make_move_if_noexcept_iterator(__c.begin()),
__make_move_if_noexcept_iterator(__c.end()),
__c.get_allocator()).swap(__c);
return true;
}
catch(...)
{ return false; }
#else
return false;
#endif
}
};
#endif
/**
* Destroy a range of objects using the supplied allocator. For
* non-default allocators we do not optimize away invocation of
* destroy() even if _Tp has a trivial destructor.
*/
template<typename _ForwardIterator, typename _Allocator>
_GLIBCXX20_CONSTEXPR
void
_Destroy(_ForwardIterator __first, _ForwardIterator __last,
_Allocator& __alloc)
{
for (; __first != __last; ++__first)
#if __cplusplus < 201103L
__alloc.destroy(std::__addressof(*__first));
#else
allocator_traits<_Allocator>::destroy(__alloc,
std::__addressof(*__first));
#endif
}
#if _GLIBCXX_HOSTED
template<typename _ForwardIterator, typename _Tp>
__attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR
inline void
_Destroy(_ForwardIterator __first, _ForwardIterator __last,
allocator<_Tp>&)
{
_Destroy(__first, __last);
}
#endif
/// @endcond
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // _ALLOC_TRAITS_H