libcxx/include/__cxx03/__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 <__cxx03/__algorithm/ranges_min_element.h>
  13 #include <__cxx03/__assert>
  14 #include <__cxx03/__concepts/copyable.h>
  15 #include <__cxx03/__config>
  16 #include <__cxx03/__functional/identity.h>
  17 #include <__cxx03/__functional/invoke.h>
  18 #include <__cxx03/__functional/ranges_operations.h>
  19 #include <__cxx03/__iterator/concepts.h>
  20 #include <__cxx03/__iterator/projected.h>
  21 #include <__cxx03/__ranges/access.h>
  22 #include <__cxx03/__ranges/concepts.h>
  23 #include <__cxx03/__type_traits/is_trivially_copyable.h>
  24 #include <__cxx03/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 <__cxx03/__undef_macros>
  34
  35 _LIBCPP_BEGIN_NAMESPACE_STD
  36
  37 namespace ranges {
  38 namespace __min {
  39 struct __fn {
  40   template <class _Tp,
  41             class _Proj                                                    = identity,
  42             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
  43   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp&
  44   operator()(_LIBCPP_LIFETIMEBOUND const _Tp& __a,
  45              _LIBCPP_LIFETIMEBOUND const _Tp& __b,
  46              _Comp __comp = {},
  47              _Proj __proj = {}) const {
  48     return std::invoke(__comp, std::invoke(__proj, __b), std::invoke(__proj, __a)) ? __b : __a;
  49   }
  50
  51   template <copyable _Tp,
  52             class _Proj                                                    = identity,
  53             indirect_strict_weak_order<projected<const _Tp*, _Proj>> _Comp = ranges::less>
  54   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp
  55   operator()(initializer_list<_Tp> __il, _Comp __comp = {}, _Proj __proj = {}) const {
  56     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
  57         __il.begin() != __il.end(), "initializer_list must contain at least one element");
  58     return *ranges::__min_element_impl(__il.begin(), __il.end(), __comp, __proj);
  59   }
  60
  61   template <input_range _Rp,
  62             class _Proj                                                         = identity,
  63             indirect_strict_weak_order<projected<iterator_t<_Rp>, _Proj>> _Comp = ranges::less>
  64     requires indirectly_copyable_storable<iterator_t<_Rp>, range_value_t<_Rp>*>
  65   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr range_value_t<_Rp>
  66   operator()(_Rp&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
  67     auto __first = ranges::begin(__r);
  68     auto __last  = ranges::end(__r);
  69     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__first != __last, "range must contain at least one element");
  70     if constexpr (forward_range<_Rp> && !__is_cheap_to_copy<range_value_t<_Rp>>) {
  71       return *ranges::__min_element_impl(__first, __last, __comp, __proj);
  72     } else {
  73       range_value_t<_Rp> __result = *__first;
  74       while (++__first != __last) {
  75         if (std::invoke(__comp, std::invoke(__proj, *__first), std::invoke(__proj, __result)))
  76           __result = *__first;
  77       }
  78       return __result;
  79     }
  80   }
  81 };
  82 } // namespace __min
  83
  84 inline namespace __cpo {
  85 inline constexpr auto min = __min::__fn{};
  86 } // namespace __cpo
  87 } // namespace ranges
  88
  89 _LIBCPP_END_NAMESPACE_STD
  90
  91 _LIBCPP_POP_MACROS
  92
  93 #endif // _LIBCPP_STD_VER >= 20
  94
  95 #endif // _LIBCPP___ALGORITHM_RANGES_MIN_H