__cxx03/__algorithm/ranges_min.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___CXX03___ALGORITHM_RANGES_MIN_H
0010 #define _LIBCPP___CXX03___ALGORITHM_RANGES_MIN_H
0011
0012 #include <__cxx03/__algorithm/ranges_min_element.h>
0013 #include <__cxx03/__assert>
0014 #include <__cxx03/__concepts/copyable.h>
0015 #include <__cxx03/__config>
0016 #include <__cxx03/__functional/identity.h>
0017 #include <__cxx03/__functional/invoke.h>
0018 #include <__cxx03/__functional/ranges_operations.h>
0019 #include <__cxx03/__iterator/concepts.h>
0020 #include <__cxx03/__iterator/projected.h>
0021 #include <__cxx03/__ranges/access.h>
0022 #include <__cxx03/__ranges/concepts.h>
0023 #include <__cxx03/__type_traits/is_trivially_copyable.h>
0024 #include <__cxx03/initializer_list>
0025
0026 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0027 #  pragma GCC system_header
0028 #endif
0029
0030 #if _LIBCPP_STD_VER >= 20
0031
0032 _LIBCPP_PUSH_MACROS
0033 #  include <__cxx03/__undef_macros>
0034
0035 _LIBCPP_BEGIN_NAMESPACE_STD
0036
0037 namespace ranges {
0038 namespace __min {
0039 struct __fn {
0040   template <class _Tp,
0041             class _Proj                                                    = identity,
0042             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
0043   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp&
0044   operator()(_LIBCPP_LIFETIMEBOUND const _Tp& __a,
0045              _LIBCPP_LIFETIMEBOUND const _Tp& __b,
0046              _Comp __comp = {},
0047              _Proj __proj = {}) const {
0048     return std::invoke(__comp, std::invoke(__proj, __b), std::invoke(__proj, __a)) ? __b : __a;
0049   }
0050
0051   template <copyable _Tp,
0052             class _Proj                                                    = identity,
0053             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
0054   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp
0055   operator()(initializer_list<_Tp> __il, _Comp __comp = {}, _Proj __proj = {}) const {
0056     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
0057         __il.begin() != __il.end(), "initializer_list must contain at least one element");
0058     return *ranges::__min_element_impl(__il.begin(), __il.end(), __comp, __proj);
0059   }
0060
0061   template <input_range _Rp,
0062             class _Proj                                                         = identity,
0063             indirect_strict_weak_order<projected<iterator_t<_Rp>, _Proj>> _Comp = ranges::less>
0064     requires indirectly_copyable_storable<iterator_t<_Rp>, range_value_t<_Rp>*>
0065   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr range_value_t<_Rp>
0066   operator()(_Rp&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
0067     auto __first = ranges::begin(__r);
0068     auto __last  = ranges::end(__r);
0069     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__first != __last, "range must contain at least one element");
0070     if constexpr (forward_range<_Rp> && !__is_cheap_to_copy<range_value_t<_Rp>>) {
0071       return *ranges::__min_element_impl(__first, __last, __comp, __proj);
0072     } else {
0073       range_value_t<_Rp> __result = *__first;
0074       while (++__first != __last) {
0075         if (std::invoke(__comp, std::invoke(__proj, *__first), std::invoke(__proj, __result)))
0076           __result = *__first;
0077       }
0078       return __result;
0079     }
0080   }
0081 };
0082 } // namespace __min
0083
0084 inline namespace __cpo {
0085 inline constexpr auto min = __min::__fn{};
0086 } // namespace __cpo
0087 } // namespace ranges
0088
0089 _LIBCPP_END_NAMESPACE_STD
0090
0091 _LIBCPP_POP_MACROS
0092
0093 #endif // _LIBCPP_STD_VER >= 20
0094
0095 #endif // _LIBCPP___CXX03___ALGORITHM_RANGES_MIN_H