v3/algorithm/minmax.hpp

0001 /// \file
0002 // Range v3 library
0003 //
0004 //  Copyright Eric Niebler 2014-present
0005 //  Copyright Casey Carter 2015
0006 //
0007 //  Use, modification and distribution is subject to the
0008 //  Boost Software License, Version 1.0. (See accompanying
0009 //  file LICENSE_1_0.txt or copy at
0010 //  http://www.boost.org/LICENSE_1_0.txt)
0011 //
0012 // Project home: https://github.com/ericniebler/range-v3
0013 //
0014 #ifndef RANGES_V3_ALGORITHM_MINMAX_HPP
0015 #define RANGES_V3_ALGORITHM_MINMAX_HPP
0016
0017 #include <initializer_list>
0018
0019 #include <range/v3/range_fwd.hpp>
0020
0021 #include <range/v3/algorithm/result_types.hpp>
0022 #include <range/v3/functional/comparisons.hpp>
0023 #include <range/v3/functional/identity.hpp>
0024 #include <range/v3/functional/invoke.hpp>
0025 #include <range/v3/iterator/concepts.hpp>
0026 #include <range/v3/iterator/traits.hpp>
0027 #include <range/v3/range/access.hpp>
0028 #include <range/v3/range/concepts.hpp>
0029 #include <range/v3/range/traits.hpp>
0030 #include <range/v3/utility/static_const.hpp>
0031
0032 #include <range/v3/detail/prologue.hpp>
0033
0034 namespace ranges
0035 {
0036     /// \addtogroup group-algorithms
0037     /// @{
0038     template<typename T>
0039     using minmax_result = detail::min_max_result<T, T>;
0040
0041     RANGES_FUNC_BEGIN(minmax)
0042
0043         /// \brief function template \c minmax
0044         template(typename T, typename C = less, typename P = identity)(
0045             requires indirect_strict_weak_order<C, projected<T const *, P>>)
0046         constexpr minmax_result<T const &> RANGES_FUNC(minmax)(
0047             T const & a, T const & b, C pred = C{}, P proj = P{}) //
0048         {
0049             using R = minmax_result<T const &>;
0050             return invoke(pred, invoke(proj, b), invoke(proj, a)) ? R{b, a} : R{a, b};
0051         }
0052
0053         /// \overload
0054         template(typename Rng, typename C = less, typename P = identity)(
0055             requires input_range<Rng> AND
0056             indirect_strict_weak_order<C, projected<iterator_t<Rng>, P>> AND
0057             indirectly_copyable_storable<iterator_t<Rng>, range_value_t<Rng> *>)
0058         constexpr minmax_result<range_value_t<Rng>> //
0059         RANGES_FUNC(minmax)(Rng && rng, C pred = C{}, P proj = P{}) //
0060         {
0061             using R = minmax_result<range_value_t<Rng>>;
0062             auto first = ranges::begin(rng);
0063             auto last = ranges::end(rng);
0064             RANGES_EXPECT(first != last);
0065             auto result = R{*first, *first};
0066             if(++first != last)
0067             {
0068                 {
0069                     auto && tmp = *first;
0070                     if(invoke(pred, invoke(proj, tmp), invoke(proj, result.min)))
0071                         result.min = (decltype(tmp) &&)tmp;
0072                     else
0073                         result.max = (decltype(tmp) &&)tmp;
0074                 }
0075                 while(++first != last)
0076                 {
0077                     range_value_t<Rng> tmp1 = *first;
0078                     if(++first == last)
0079                     {
0080                         if(invoke(pred, invoke(proj, tmp1), invoke(proj, result.min)))
0081                             result.min = std::move(tmp1);
0082                         else if(!invoke(
0083                                     pred, invoke(proj, tmp1), invoke(proj, result.max)))
0084                             result.max = std::move(tmp1);
0085                         break;
0086                     }
0087
0088                     auto && tmp2 = *first;
0089                     if(invoke(pred, invoke(proj, tmp2), invoke(proj, tmp1)))
0090                     {
0091                         if(invoke(pred, invoke(proj, tmp2), invoke(proj, result.min)))
0092                             result.min = (decltype(tmp2) &&)tmp2;
0093                         if(!invoke(pred, invoke(proj, tmp1), invoke(proj, result.max)))
0094                             result.max = std::move(tmp1);
0095                     }
0096                     else
0097                     {
0098                         if(invoke(pred, invoke(proj, tmp1), invoke(proj, result.min)))
0099                             result.min = std::move(tmp1);
0100                         if(!invoke(pred, invoke(proj, tmp2), invoke(proj, result.max)))
0101                             result.max = (decltype(tmp2) &&)tmp2;
0102                     }
0103                 }
0104             }
0105             return result;
0106         }
0107
0108         /// \overload
0109         template(typename T, typename C = less, typename P = identity)(
0110             requires copyable<T> AND
0111                 indirect_strict_weak_order<C, projected<T const *, P>>)
0112         constexpr minmax_result<T> RANGES_FUNC(minmax)(
0113             std::initializer_list<T> const && rng, C pred = C{}, P proj = P{}) //
0114         {
0115             return (*this)(rng, std::move(pred), std::move(proj));
0116         }
0117
0118     RANGES_FUNC_END(minmax)
0119
0120     namespace cpp20
0121     {
0122         using ranges::minmax;
0123         using ranges::minmax_result;
0124     } // namespace cpp20
0125     /// @}
0126 } // namespace ranges
0127
0128 #include <range/v3/detail/epilogue.hpp>
0129
0130 #endif