v3/view/take_while.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_TAKE_WHILE_HPP
0015 #define RANGES_V3_VIEW_TAKE_WHILE_HPP
0016
0017 #include <type_traits>
0018 #include <utility>
0019
0020 #include <meta/meta.hpp>
0021
0022 #include <range/v3/range_fwd.hpp>
0023
0024 #include <range/v3/functional/bind_back.hpp>
0025 #include <range/v3/functional/compose.hpp>
0026 #include <range/v3/functional/indirect.hpp>
0027 #include <range/v3/functional/invoke.hpp>
0028 #include <range/v3/iterator/concepts.hpp>
0029 #include <range/v3/range/concepts.hpp>
0030 #include <range/v3/utility/semiregular_box.hpp>
0031 #include <range/v3/utility/static_const.hpp>
0032 #include <range/v3/view/adaptor.hpp>
0033 #include <range/v3/view/view.hpp>
0034
0035 #include <range/v3/detail/prologue.hpp>
0036
0037 namespace ranges
0038 {
0039     /// \addtogroup group-views
0040     /// @{
0041     template<typename Rng, typename Pred>
0042     struct iter_take_while_view
0043       : view_adaptor<iter_take_while_view<Rng, Pred>, Rng,
0044                      is_finite<Rng>::value ? finite : unknown>
0045     {
0046     private:
0047         friend range_access;
0048         RANGES_NO_UNIQUE_ADDRESS semiregular_box_t<Pred> pred_;
0049
0050         template<bool IsConst>
0051         struct sentinel_adaptor : adaptor_base
0052         {
0053         private:
0054             friend struct sentinel_adaptor<!IsConst>;
0055             using CRng = meta::const_if_c<IsConst, Rng>;
0056             RANGES_NO_UNIQUE_ADDRESS semiregular_box_ref_or_val_t<Pred, IsConst> pred_;
0057
0058         public:
0059             sentinel_adaptor() = default;
0060             sentinel_adaptor(semiregular_box_ref_or_val_t<Pred, IsConst> pred)
0061               : pred_(std::move(pred))
0062             {}
0063             template(bool Other)(
0064                 requires IsConst AND CPP_NOT(Other)) //
0065                 sentinel_adaptor(sentinel_adaptor<Other> that)
0066               : pred_(std::move(that.pred_))
0067             {}
0068             bool empty(iterator_t<CRng> const & it, sentinel_t<CRng> const & last) const
0069             {
0070                 return it == last || !invoke(pred_, it);
0071             }
0072         };
0073         sentinel_adaptor<false> end_adaptor()
0074         {
0075             return {pred_};
0076         }
0077         template(bool Const = true)(
0078             requires Const AND range<meta::const_if_c<Const, Rng>> AND
0079                 invocable<Pred const &, iterator_t<meta::const_if_c<Const, Rng>>>)
0080         sentinel_adaptor<Const> end_adaptor() const
0081         {
0082             return {pred_};
0083         }
0084
0085     public:
0086         iter_take_while_view() = default;
0087         constexpr iter_take_while_view(Rng rng, Pred pred)
0088           : iter_take_while_view::view_adaptor{std::move(rng)}
0089           , pred_(std::move(pred))
0090         {}
0091     };
0092
0093     template<typename Rng, typename Pred>
0094     struct take_while_view : iter_take_while_view<Rng, indirected<Pred>>
0095     {
0096         take_while_view() = default;
0097         constexpr take_while_view(Rng rng, Pred pred)
0098           : iter_take_while_view<Rng, indirected<Pred>>{std::move(rng),
0099                                                         indirect(std::move(pred))}
0100         {}
0101     };
0102
0103 #if RANGES_CXX_DEDUCTION_GUIDES >= RANGES_CXX_DEDUCTION_GUIDES_17
0104     template(typename Rng, typename Fun)(
0105         requires copy_constructible<Fun>)
0106     take_while_view(Rng &&, Fun)
0107         -> take_while_view<views::all_t<Rng>, Fun>;
0108 #endif
0109
0110     namespace views
0111     {
0112         struct iter_take_while_base_fn
0113         {
0114             template(typename Rng, typename Pred)(
0115                 requires viewable_range<Rng> AND input_range<Rng> AND
0116                     predicate<Pred &, iterator_t<Rng>> AND copy_constructible<Pred>)
0117             constexpr iter_take_while_view<all_t<Rng>, Pred> //
0118             operator()(Rng && rng, Pred pred) const
0119             {
0120                 return {all(static_cast<Rng &&>(rng)), std::move(pred)};
0121             }
0122         };
0123
0124         struct iter_take_while_fn : iter_take_while_base_fn
0125         {
0126             using iter_take_while_base_fn::operator();
0127
0128             template<typename Pred>
0129             constexpr auto operator()(Pred pred) const
0130             {
0131                 return make_view_closure(
0132                     bind_back(iter_take_while_base_fn{}, std::move(pred)));
0133             }
0134         };
0135
0136         struct take_while_base_fn
0137         {
0138             template(typename Rng, typename Pred)(
0139                 requires viewable_range<Rng> AND input_range<Rng> AND
0140                     indirect_unary_predicate<Pred &, iterator_t<Rng>>)
0141             constexpr take_while_view<all_t<Rng>, Pred> //
0142             operator()(Rng && rng, Pred pred) const
0143             {
0144                 return {all(static_cast<Rng &&>(rng)), std::move(pred)};
0145             }
0146             template(typename Rng, typename Pred, typename Proj)(
0147                 requires viewable_range<Rng> AND input_range<Rng> AND
0148                     indirect_unary_predicate<composed<Pred, Proj> &, iterator_t<Rng>>)
0149             constexpr take_while_view<all_t<Rng>, composed<Pred, Proj>> //
0150             operator()(Rng && rng, Pred pred, Proj proj) const
0151             {
0152                 return {all(static_cast<Rng &&>(rng)),
0153                         compose(std::move(pred), std::move(proj))};
0154             }
0155         };
0156
0157         struct take_while_bind_fn
0158         {
0159             template<typename Pred>
0160             constexpr auto operator()(Pred pred) const // TODO: underconstrained
0161             {
0162                 return make_view_closure(
0163                     bind_back(take_while_base_fn{}, std::move(pred)));
0164             }
0165             template(typename Pred, typename Proj)(
0166                 requires (!range<Pred>)) // TODO: underconstrained
0167             constexpr auto operator()(Pred && pred, Proj proj) const
0168
0169             {
0170                 return make_view_closure(bind_back(
0171                     take_while_base_fn{}, static_cast<Pred &&>(pred), std::move(proj)));
0172             }
0173         };
0174
0175         struct RANGES_EMPTY_BASES take_while_fn
0176           : take_while_base_fn, take_while_bind_fn
0177         {
0178             using take_while_base_fn::operator();
0179             using take_while_bind_fn::operator();
0180         };
0181
0182         /// \relates iter_take_while_fn
0183         /// \ingroup group-views
0184         RANGES_INLINE_VARIABLE(iter_take_while_fn, iter_take_while)
0185
0186         /// \relates take_while_fn
0187         /// \ingroup group-views
0188         RANGES_INLINE_VARIABLE(take_while_fn, take_while)
0189     } // namespace views
0190
0191     namespace cpp20
0192     {
0193         namespace views
0194         {
0195             using ranges::views::take_while;
0196         }
0197         template(typename Rng, typename Pred)(
0198             requires viewable_range<Rng> AND input_range<Rng> AND
0199                 predicate<Pred &, iterator_t<Rng>> AND copy_constructible<Pred>)
0200             using take_while_view = ranges::take_while_view<Rng, Pred>;
0201     } // namespace cpp20
0202     /// @}
0203 } // namespace ranges
0204
0205 #include <range/v3/detail/epilogue.hpp>
0206 #include <range/v3/detail/satisfy_boost_range.hpp>
0207 RANGES_SATISFY_BOOST_RANGE(::ranges::iter_take_while_view)
0208 RANGES_SATISFY_BOOST_RANGE(::ranges::take_while_view)
0209
0210 #endif