v3/algorithm/minmax_element.hpp

0001 /// \file
0002 // Range v3 library
0003 //
0004 //  Copyright Eric Niebler 2014-present
0005 //
0006 //  Use, modification and distribution is subject to the
0007 //  Boost Software License, Version 1.0. (See accompanying
0008 //  file LICENSE_1_0.txt or copy at
0009 //  http://www.boost.org/LICENSE_1_0.txt)
0010 //
0011 // Project home: https://github.com/ericniebler/range-v3
0012 //
0013 // Implementation based on the code in libc++
0014 //   http://http://libcxx.llvm.org/
0015
0016 #ifndef RANGES_V3_ALGORITHM_MINMAX_ELEMENT_HPP
0017 #define RANGES_V3_ALGORITHM_MINMAX_ELEMENT_HPP
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/dangling.hpp>
0030 #include <range/v3/range/traits.hpp>
0031 #include <range/v3/utility/static_const.hpp>
0032
0033 #include <range/v3/detail/prologue.hpp>
0034
0035 namespace ranges
0036 {
0037     /// \addtogroup group-algorithms
0038     /// @{
0039     template<typename I>
0040     using minmax_element_result = detail::min_max_result<I, I>;
0041
0042     RANGES_FUNC_BEGIN(minmax_element)
0043
0044         /// \brief function template \c minmax_element
0045         template(typename I, typename S, typename C = less, typename P = identity)(
0046             requires forward_iterator<I> AND sentinel_for<S, I> AND
0047             indirect_strict_weak_order<C, projected<I, P>>)
0048         constexpr minmax_element_result<I> //
0049         RANGES_FUNC(minmax_element)(I first, S last, C pred = C{}, P proj = P{}) //
0050         {
0051             minmax_element_result<I> result{first, first};
0052             if(first == last || ++first == last)
0053                 return result;
0054             if(invoke(pred, invoke(proj, *first), invoke(proj, *result.min)))
0055                 result.min = first;
0056             else
0057                 result.max = first;
0058             while(++first != last)
0059             {
0060                 I tmp = first;
0061                 if(++first == last)
0062                 {
0063                     if(invoke(pred, invoke(proj, *tmp), invoke(proj, *result.min)))
0064                         result.min = tmp;
0065                     else if(!invoke(pred, invoke(proj, *tmp), invoke(proj, *result.max)))
0066                         result.max = tmp;
0067                     break;
0068                 }
0069                 else
0070                 {
0071                     if(invoke(pred, invoke(proj, *first), invoke(proj, *tmp)))
0072                     {
0073                         if(invoke(pred, invoke(proj, *first), invoke(proj, *result.min)))
0074                             result.min = first;
0075                         if(!invoke(pred, invoke(proj, *tmp), invoke(proj, *result.max)))
0076                             result.max = tmp;
0077                     }
0078                     else
0079                     {
0080                         if(invoke(pred, invoke(proj, *tmp), invoke(proj, *result.min)))
0081                             result.min = tmp;
0082                         if(!invoke(pred, invoke(proj, *first), invoke(proj, *result.max)))
0083                             result.max = first;
0084                     }
0085                 }
0086             }
0087             return result;
0088         }
0089
0090         /// \overload
0091         template(typename Rng, typename C = less, typename P = identity)(
0092             requires forward_range<Rng> AND
0093             indirect_strict_weak_order<C, projected<iterator_t<Rng>, P>>)
0094         constexpr minmax_element_result<borrowed_iterator_t<Rng>> //
0095         RANGES_FUNC(minmax_element)(Rng && rng, C pred = C{}, P proj = P{}) //
0096         {
0097             return (*this)(begin(rng), end(rng), std::move(pred), std::move(proj));
0098         }
0099
0100     RANGES_FUNC_END(minmax_element)
0101
0102     namespace cpp20
0103     {
0104         using ranges::minmax_element;
0105         using ranges::minmax_element_result;
0106     } // namespace cpp20
0107     /// @}
0108 } // namespace ranges
0109
0110 #include <range/v3/detail/epilogue.hpp>
0111
0112 #endif