v3/view/ref.hpp

0001 /// \file
0002 // Range v3 library
0003 //
0004 //  Copyright Eric Niebler 2013-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
0014 #ifndef RANGES_V3_VIEW_REF_HPP
0015 #define RANGES_V3_VIEW_REF_HPP
0016
0017 #include <concepts/concepts.hpp>
0018
0019 #include <range/v3/range_fwd.hpp>
0020
0021 #include <range/v3/range/access.hpp>
0022 #include <range/v3/range/primitives.hpp>
0023 #include <range/v3/range/traits.hpp>
0024 #include <range/v3/utility/addressof.hpp>
0025 #include <range/v3/view/interface.hpp>
0026
0027 #include <range/v3/detail/prologue.hpp>
0028
0029 namespace ranges
0030 {
0031     template<typename Rng>
0032     struct ref_view;
0033
0034     template<typename Rng>
0035     RANGES_INLINE_VAR constexpr bool enable_borrowed_range<ref_view<Rng>> = true;
0036
0037     /// \addtogroup group-views
0038     /// @{
0039     template<typename Rng>
0040     struct ref_view : view_interface<ref_view<Rng>, range_cardinality<Rng>::value>
0041     {
0042     private:
0043         CPP_assert(range<Rng>);
0044         static_assert(std::is_object<Rng>::value, "");
0045         Rng * rng_ = nullptr; // exposition only
0046     public:
0047         constexpr ref_view() noexcept = default;
0048         constexpr ref_view(Rng & rng) noexcept
0049           : rng_(detail::addressof(rng))
0050         {}
0051         constexpr Rng & base() const noexcept
0052         {
0053             return *rng_;
0054         }
0055         constexpr iterator_t<Rng> begin() const noexcept(noexcept(ranges::begin(*rng_)))
0056         {
0057             return ranges::begin(*rng_);
0058         }
0059         constexpr sentinel_t<Rng> end() const noexcept(noexcept(ranges::end(*rng_)))
0060         {
0061             return ranges::end(*rng_);
0062         }
0063         CPP_member
0064         constexpr auto empty() const noexcept(noexcept(ranges::empty(*rng_)))
0065             -> CPP_ret(bool)(
0066                 requires detail::can_empty_<Rng>)
0067         {
0068             return ranges::empty(*rng_);
0069         }
0070         CPP_auto_member
0071         constexpr auto CPP_fun(size)()(const //
0072             noexcept(noexcept(ranges::size(*rng_))) //
0073             requires sized_range<Rng>)
0074         {
0075             return ranges::size(*rng_);
0076         }
0077         CPP_auto_member
0078         constexpr auto CPP_fun(data)()(const //
0079             noexcept(noexcept(ranges::data(*rng_))) //
0080             requires contiguous_range<Rng>)
0081         {
0082             return ranges::data(*rng_);
0083         }
0084     };
0085
0086 #if RANGES_CXX_DEDUCTION_GUIDES >= RANGES_CXX_DEDUCTION_GUIDES_17
0087     template(typename R)(
0088         requires range<R>)
0089     ref_view(R &) //
0090         -> ref_view<R>;
0091 #endif
0092
0093     namespace views
0094     {
0095         struct ref_fn
0096         {
0097             template(typename Rng)(
0098                 requires range<Rng>)
0099             constexpr ref_view<Rng> operator()(Rng & rng) const noexcept
0100             {
0101                 return ref_view<Rng>(rng);
0102             }
0103             template<typename Rng>
0104             void operator()(Rng const && rng) const = delete;
0105         };
0106
0107         /// \relates const_fn
0108         /// \ingroup group-views
0109         RANGES_INLINE_VARIABLE(ref_fn, ref)
0110     } // namespace views
0111
0112     namespace cpp20
0113     {
0114         template(typename Rng)(
0115             requires std::is_object<Rng>::value) //
0116             using ref_view = ranges::ref_view<Rng>;
0117     }
0118 } // namespace ranges
0119
0120 #include <range/v3/detail/satisfy_boost_range.hpp>
0121 RANGES_SATISFY_BOOST_RANGE(::ranges::ref_view)
0122
0123 #include <range/v3/detail/epilogue.hpp>
0124
0125 #endif