2021-04-11 05:08:32 +00:00
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// -*- C++ -*-
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2021-11-17 21:25:01 +00:00
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//===----------------------------------------------------------------------===//
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2021-04-11 05:08:32 +00:00
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___RANGES_ACCESS_H
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#define _LIBCPP___RANGES_ACCESS_H
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2021-12-23 21:53:48 +00:00
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#include <__concepts/class_or_enum.h>
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#include <__config>
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#include <__iterator/concepts.h>
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2021-06-12 06:13:44 +00:00
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#include <__iterator/readable_traits.h>
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2021-04-11 05:08:32 +00:00
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#include <__ranges/enable_borrowed_range.h>
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2021-12-14 00:21:38 +00:00
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#include <__utility/auto_cast.h>
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#include <type_traits>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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2022-02-02 01:16:40 +00:00
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# pragma GCC system_header
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2021-04-11 05:08:32 +00:00
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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2022-03-12 15:46:57 +00:00
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#if _LIBCPP_STD_VER > 17
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namespace ranges {
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template <class _Tp>
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concept __can_borrow =
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is_lvalue_reference_v<_Tp> || enable_borrowed_range<remove_cvref_t<_Tp>>;
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} // namespace ranges
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// [range.access.begin]
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2021-12-23 19:51:24 +00:00
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namespace ranges {
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namespace __begin {
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template <class _Tp>
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concept __member_begin =
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__can_borrow<_Tp> &&
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__workaround_52970<_Tp> &&
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requires(_Tp&& __t) {
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{ _LIBCPP_AUTO_CAST(__t.begin()) } -> input_or_output_iterator;
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};
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void begin(auto&) = delete;
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void begin(const auto&) = delete;
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template <class _Tp>
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concept __unqualified_begin =
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!__member_begin<_Tp> &&
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__can_borrow<_Tp> &&
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__class_or_enum<remove_cvref_t<_Tp>> &&
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requires(_Tp && __t) {
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{ _LIBCPP_AUTO_CAST(begin(__t)) } -> input_or_output_iterator;
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};
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struct __fn {
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template <class _Tp>
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2022-02-04 02:41:30 +00:00
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp (&__t)[]) const noexcept
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2022-02-27 17:41:22 +00:00
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requires (sizeof(_Tp) >= 0) // Disallow incomplete element types.
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[libc++] [ranges] Remove the static_assert from ranges::begin and ranges::end.
As discussed with ldionne. The problem with this static_assert
is that it makes ranges::begin a pitfall for anyone ever to use
inside a constraint or decltype. Many Ranges things, such as ranges::size,
are specified as "Does X if X is well-formed, or else Y if Y is well-formed,
or else `ranges::end(t) - ranges::begin(t)` if that is well-formed, or else..."
And if there's a static_assert hidden inside `ranges::begin(t)`, then you get
a hard error as soon as you ask the question -- even if the answer would have
been "no, that's not well-formed"!
Constraining on `requires { t + 0; }` or `requires { t + N; }` is verboten
because of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103700 . For ranges::begin,
we can just decay to a pointer even in the incomplete-type case. For ranges::end,
we can safely constrain on `sizeof(*t)`. Yes, this means that an array of incomplete
type has a `ranges::begin` but no `ranges::end`... just like an unbounded array of
complete type. This is a valid manifestation of IFNDR.
All of the new libcxx/test/std/ cases are mandatory behavior, as far as I'm aware.
Tests for the IFNDR cases in ranges::begin and ranges::end remain in `libcxx/test/libcxx/`.
The similar tests for ranges::empty and ranges::data were simply wrong, AFAIK.
Differential Revision: https://reviews.llvm.org/D115838
2021-12-16 03:10:34 +00:00
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{
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2022-02-04 02:41:30 +00:00
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return __t + 0;
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}
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template <class _Tp, size_t _Np>
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp (&__t)[_Np]) const noexcept
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2022-02-27 17:41:22 +00:00
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requires (sizeof(_Tp) >= 0) // Disallow incomplete element types.
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2022-02-04 02:41:30 +00:00
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{
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return __t + 0;
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}
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template <class _Tp>
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requires __member_begin<_Tp>
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2021-07-19 16:34:56 +00:00
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
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noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.begin())))
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{
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return _LIBCPP_AUTO_CAST(__t.begin());
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}
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template <class _Tp>
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requires __unqualified_begin<_Tp>
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
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2021-12-23 19:51:24 +00:00
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noexcept(noexcept(_LIBCPP_AUTO_CAST(begin(__t))))
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{
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return _LIBCPP_AUTO_CAST(begin(__t));
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}
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void operator()(auto&&) const = delete;
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};
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2022-02-01 17:11:49 +00:00
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} // namespace __begin
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2021-04-11 05:08:32 +00:00
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2021-12-23 19:51:24 +00:00
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inline namespace __cpo {
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inline constexpr auto begin = __begin::__fn{};
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} // namespace __cpo
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} // namespace ranges
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// [range.range]
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namespace ranges {
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template <class _Tp>
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using iterator_t = decltype(ranges::begin(declval<_Tp&>()));
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} // namespace ranges
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// [range.access.end]
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2021-12-23 19:51:24 +00:00
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namespace ranges {
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namespace __end {
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2021-04-11 05:08:32 +00:00
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template <class _Tp>
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concept __member_end =
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__can_borrow<_Tp> &&
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__workaround_52970<_Tp> &&
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requires(_Tp&& __t) {
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typename iterator_t<_Tp>;
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{ _LIBCPP_AUTO_CAST(__t.end()) } -> sentinel_for<iterator_t<_Tp>>;
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};
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void end(auto&) = delete;
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void end(const auto&) = delete;
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template <class _Tp>
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concept __unqualified_end =
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!__member_end<_Tp> &&
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__can_borrow<_Tp> &&
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2021-12-23 19:51:24 +00:00
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__class_or_enum<remove_cvref_t<_Tp>> &&
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2021-04-11 05:08:32 +00:00
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requires(_Tp && __t) {
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typename iterator_t<_Tp>;
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2021-12-23 19:51:24 +00:00
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{ _LIBCPP_AUTO_CAST(end(__t)) } -> sentinel_for<iterator_t<_Tp>>;
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2021-04-11 05:08:32 +00:00
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};
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2022-03-22 19:34:48 +00:00
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struct __fn {
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2021-04-11 05:08:32 +00:00
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template <class _Tp, size_t _Np>
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[libc++] [ranges] Remove the static_assert from ranges::begin and ranges::end.
As discussed with ldionne. The problem with this static_assert
is that it makes ranges::begin a pitfall for anyone ever to use
inside a constraint or decltype. Many Ranges things, such as ranges::size,
are specified as "Does X if X is well-formed, or else Y if Y is well-formed,
or else `ranges::end(t) - ranges::begin(t)` if that is well-formed, or else..."
And if there's a static_assert hidden inside `ranges::begin(t)`, then you get
a hard error as soon as you ask the question -- even if the answer would have
been "no, that's not well-formed"!
Constraining on `requires { t + 0; }` or `requires { t + N; }` is verboten
because of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103700 . For ranges::begin,
we can just decay to a pointer even in the incomplete-type case. For ranges::end,
we can safely constrain on `sizeof(*t)`. Yes, this means that an array of incomplete
type has a `ranges::begin` but no `ranges::end`... just like an unbounded array of
complete type. This is a valid manifestation of IFNDR.
All of the new libcxx/test/std/ cases are mandatory behavior, as far as I'm aware.
Tests for the IFNDR cases in ranges::begin and ranges::end remain in `libcxx/test/libcxx/`.
The similar tests for ranges::empty and ranges::data were simply wrong, AFAIK.
Differential Revision: https://reviews.llvm.org/D115838
2021-12-16 03:10:34 +00:00
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp (&__t)[_Np]) const noexcept
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2022-02-27 17:41:22 +00:00
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requires (sizeof(_Tp) >= 0) // Disallow incomplete element types.
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[libc++] [ranges] Remove the static_assert from ranges::begin and ranges::end.
As discussed with ldionne. The problem with this static_assert
is that it makes ranges::begin a pitfall for anyone ever to use
inside a constraint or decltype. Many Ranges things, such as ranges::size,
are specified as "Does X if X is well-formed, or else Y if Y is well-formed,
or else `ranges::end(t) - ranges::begin(t)` if that is well-formed, or else..."
And if there's a static_assert hidden inside `ranges::begin(t)`, then you get
a hard error as soon as you ask the question -- even if the answer would have
been "no, that's not well-formed"!
Constraining on `requires { t + 0; }` or `requires { t + N; }` is verboten
because of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103700 . For ranges::begin,
we can just decay to a pointer even in the incomplete-type case. For ranges::end,
we can safely constrain on `sizeof(*t)`. Yes, this means that an array of incomplete
type has a `ranges::begin` but no `ranges::end`... just like an unbounded array of
complete type. This is a valid manifestation of IFNDR.
All of the new libcxx/test/std/ cases are mandatory behavior, as far as I'm aware.
Tests for the IFNDR cases in ranges::begin and ranges::end remain in `libcxx/test/libcxx/`.
The similar tests for ranges::empty and ranges::data were simply wrong, AFAIK.
Differential Revision: https://reviews.llvm.org/D115838
2021-12-16 03:10:34 +00:00
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{
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return __t + _Np;
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2021-04-11 05:08:32 +00:00
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}
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template <class _Tp>
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2021-12-23 19:51:24 +00:00
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requires __member_end<_Tp>
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2021-07-19 16:34:56 +00:00
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
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2021-12-23 19:51:24 +00:00
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noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.end())))
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2021-04-11 05:08:32 +00:00
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{
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2021-12-14 00:21:38 +00:00
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return _LIBCPP_AUTO_CAST(__t.end());
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2021-04-11 05:08:32 +00:00
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}
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template <class _Tp>
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2021-12-23 19:51:24 +00:00
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requires __unqualified_end<_Tp>
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2021-07-19 16:34:56 +00:00
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
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2021-12-23 19:51:24 +00:00
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noexcept(noexcept(_LIBCPP_AUTO_CAST(end(__t))))
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2021-04-11 05:08:32 +00:00
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{
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2021-12-14 00:21:38 +00:00
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return _LIBCPP_AUTO_CAST(end(__t));
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2021-04-11 05:08:32 +00:00
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}
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void operator()(auto&&) const = delete;
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};
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2022-02-01 17:11:49 +00:00
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} // namespace __end
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2021-04-11 05:08:32 +00:00
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2021-12-23 19:51:24 +00:00
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inline namespace __cpo {
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2021-04-11 05:08:32 +00:00
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inline constexpr auto end = __end::__fn{};
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2021-12-23 19:51:24 +00:00
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} // namespace __cpo
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} // namespace ranges
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// [range.access.cbegin]
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2021-04-11 05:08:32 +00:00
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2021-12-23 19:51:24 +00:00
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namespace ranges {
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namespace __cbegin {
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2021-04-11 05:08:32 +00:00
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struct __fn {
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template <class _Tp>
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requires is_lvalue_reference_v<_Tp&&>
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2021-12-23 03:36:42 +00:00
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
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2022-01-11 04:37:01 +00:00
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constexpr auto operator()(_Tp&& __t) const
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noexcept(noexcept(ranges::begin(static_cast<const remove_reference_t<_Tp>&>(__t))))
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-> decltype( ranges::begin(static_cast<const remove_reference_t<_Tp>&>(__t)))
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{ return ranges::begin(static_cast<const remove_reference_t<_Tp>&>(__t)); }
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2021-04-11 05:08:32 +00:00
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template <class _Tp>
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requires is_rvalue_reference_v<_Tp&&>
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
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constexpr auto operator()(_Tp&& __t) const
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noexcept(noexcept(ranges::begin(static_cast<const _Tp&&>(__t))))
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-> decltype( ranges::begin(static_cast<const _Tp&&>(__t)))
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{ return ranges::begin(static_cast<const _Tp&&>(__t)); }
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2021-04-11 05:08:32 +00:00
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};
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2022-02-01 17:11:49 +00:00
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} // namespace __cbegin
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2021-04-11 05:08:32 +00:00
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2021-12-23 19:51:24 +00:00
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inline namespace __cpo {
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2021-04-11 05:08:32 +00:00
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inline constexpr auto cbegin = __cbegin::__fn{};
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2021-12-23 19:51:24 +00:00
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} // namespace __cpo
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} // namespace ranges
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2021-04-11 05:08:32 +00:00
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2021-12-23 19:51:24 +00:00
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// [range.access.cend]
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namespace ranges {
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namespace __cend {
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struct __fn {
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template <class _Tp>
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requires is_lvalue_reference_v<_Tp&&>
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2021-12-23 03:36:42 +00:00
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
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2022-01-11 04:37:01 +00:00
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constexpr auto operator()(_Tp&& __t) const
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noexcept(noexcept(ranges::end(static_cast<const remove_reference_t<_Tp>&>(__t))))
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-> decltype( ranges::end(static_cast<const remove_reference_t<_Tp>&>(__t)))
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{ return ranges::end(static_cast<const remove_reference_t<_Tp>&>(__t)); }
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2021-04-11 05:08:32 +00:00
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template <class _Tp>
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2021-12-23 03:36:42 +00:00
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requires is_rvalue_reference_v<_Tp&&>
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
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constexpr auto operator()(_Tp&& __t) const
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noexcept(noexcept(ranges::end(static_cast<const _Tp&&>(__t))))
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-> decltype( ranges::end(static_cast<const _Tp&&>(__t)))
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{ return ranges::end(static_cast<const _Tp&&>(__t)); }
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2021-04-11 05:08:32 +00:00
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};
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2022-02-01 17:11:49 +00:00
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} // namespace __cend
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2021-04-11 05:08:32 +00:00
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2021-12-23 19:51:24 +00:00
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inline namespace __cpo {
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2021-04-11 05:08:32 +00:00
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inline constexpr auto cend = __cend::__fn{};
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2021-12-23 19:51:24 +00:00
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} // namespace __cpo
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} // namespace ranges
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2021-04-11 05:08:32 +00:00
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2022-03-12 15:46:57 +00:00
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#endif // _LIBCPP_STD_VER > 17
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2021-04-11 05:08:32 +00:00
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___RANGES_ACCESS_H
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