v3/algorithm/max.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_MAX_HPP
0015 #define RANGES_V3_ALGORITHM_MAX_HPP
0016
0017 #include <initializer_list>
0018
0019 #include <range/v3/range_fwd.hpp>
0020
0021 #include <range/v3/functional/comparisons.hpp>
0022 #include <range/v3/functional/identity.hpp>
0023 #include <range/v3/functional/invoke.hpp>
0024 #include <range/v3/iterator/concepts.hpp>
0025 #include <range/v3/iterator/traits.hpp>
0026 #include <range/v3/range/access.hpp>
0027 #include <range/v3/range/concepts.hpp>
0028 #include <range/v3/range/traits.hpp>
0029 #include <range/v3/utility/static_const.hpp>
0030
0031 #include <range/v3/detail/prologue.hpp>
0032
0033 namespace ranges
0034 {
0035     /// \addtogroup group-algorithms
0036     /// @{
0037     RANGES_FUNC_BEGIN(max)
0038
0039         /// \brief function template \c max
0040         template(typename T, typename C = less, typename P = identity)(
0041             requires indirect_strict_weak_order<C, projected<T const *, P>>)
0042         constexpr T const & RANGES_FUNC(max)(
0043             T const & a, T const & b, C pred = C{}, P proj = P{}) //
0044         {
0045             return invoke(pred, invoke(proj, b), invoke(proj, a)) ? a : b;
0046         }
0047
0048         /// \overload
0049         template(typename Rng, typename C = less, typename P = identity)(
0050             requires input_range<Rng> AND
0051             indirect_strict_weak_order<C, projected<iterator_t<Rng>, P>> AND
0052             indirectly_copyable_storable<iterator_t<Rng>, range_value_t<Rng> *>)
0053         constexpr range_value_t<Rng> //
0054         RANGES_FUNC(max)(Rng && rng, C pred = C{}, P proj = P{}) //
0055         {
0056             auto first = ranges::begin(rng);
0057             auto last = ranges::end(rng);
0058             RANGES_EXPECT(first != last);
0059             range_value_t<Rng> result = *first;
0060             while(++first != last)
0061             {
0062                 auto && tmp = *first;
0063                 if(invoke(pred, invoke(proj, result), invoke(proj, tmp)))
0064                     result = (decltype(tmp) &&)tmp;
0065             }
0066             return result;
0067         }
0068
0069         /// \overload
0070         template(typename T, typename C = less, typename P = identity)(
0071             requires copyable<T> AND
0072                 indirect_strict_weak_order<C, projected<T const *, P>>)
0073         constexpr T RANGES_FUNC(max)(
0074             std::initializer_list<T> const && rng, C pred = C{}, P proj = P{}) //
0075         {
0076             return (*this)(rng, std::move(pred), std::move(proj));
0077         }
0078
0079     RANGES_FUNC_END(max)
0080
0081     namespace cpp20
0082     {
0083         using ranges::max;
0084     }
0085     /// @}
0086 } // namespace ranges
0087
0088 #include <range/v3/detail/epilogue.hpp>
0089
0090 #endif