libcxx/include/__algorithm/ranges_min.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___ALGORITHM_RANGES_MIN_H
  10 #define _LIBCPP___ALGORITHM_RANGES_MIN_H
  11
  12 #include <__algorithm/ranges_min_element.h>
  13 #include <__assert>
  14 #include <__concepts/copyable.h>
  15 #include <__config>
  16 #include <__functional/identity.h>
  17 #include <__functional/invoke.h>
  18 #include <__functional/ranges_operations.h>
  19 #include <__iterator/concepts.h>
  20 #include <__iterator/projected.h>
  21 #include <__ranges/access.h>
  22 #include <__ranges/concepts.h>
  23 #include <__type_traits/is_trivially_copyable.h>
  24 #include <initializer_list>
  25
  26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  27 #  pragma GCC system_header
  28 #endif
  29
  30 #if _LIBCPP_STD_VER >= 20
  31
  32 _LIBCPP_PUSH_MACROS
  33 #  include <__undef_macros>
  34
  35 _LIBCPP_BEGIN_NAMESPACE_STD
  36
  37 namespace ranges {
  38 struct __min {
  39   template <class _Tp,
  40             class _Proj                                                    = identity,
  41             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
  42   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp&
  43   operator()(_LIBCPP_LIFETIMEBOUND const _Tp& __a,
  44              _LIBCPP_LIFETIMEBOUND const _Tp& __b,
  45              _Comp __comp = {},
  46              _Proj __proj = {}) const {
  47     return std::invoke(__comp, std::invoke(__proj, __b), std::invoke(__proj, __a)) ? __b : __a;
  48   }
  49
  50   template <copyable _Tp,
  51             class _Proj                                                    = identity,
  52             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
  53   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp
  54   operator()(initializer_list<_Tp> __il, _Comp __comp = {}, _Proj __proj = {}) const {
  55     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
  56         __il.begin() != __il.end(), "initializer_list must contain at least one element");
  57     return *ranges::__min_element_impl(__il.begin(), __il.end(), __comp, __proj);
  58   }
  59
  60   template <input_range _Rp,
  61             class _Proj                                                         = identity,
  62             indirect_strict_weak_order<projected<iterator_t<_Rp>, _Proj>> _Comp = ranges::less>
  63     requires indirectly_copyable_storable<iterator_t<_Rp>, range_value_t<_Rp>*>
  64   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr range_value_t<_Rp>
  65   operator()(_Rp&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
  66     auto __first = ranges::begin(__r);
  67     auto __last  = ranges::end(__r);
  68     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__first != __last, "range must contain at least one element");
  69     if constexpr (forward_range<_Rp> && !__is_cheap_to_copy<range_value_t<_Rp>>) {
  70       return *ranges::__min_element_impl(__first, __last, __comp, __proj);
  71     } else {
  72       range_value_t<_Rp> __result = *__first;
  73       while (++__first != __last) {
  74         if (std::invoke(__comp, std::invoke(__proj, *__first), std::invoke(__proj, __result)))
  75           __result = *__first;
  76       }
  77       return __result;
  78     }
  79   }
  80 };
  81
  82 inline namespace __cpo {
  83 inline constexpr auto min = __min{};
  84 } // namespace __cpo
  85 } // namespace ranges
  86
  87 _LIBCPP_END_NAMESPACE_STD
  88
  89 _LIBCPP_POP_MACROS
  90
  91 #endif // _LIBCPP_STD_VER >= 20
  92
  93 #endif // _LIBCPP___ALGORITHM_RANGES_MIN_H