take_while.hpp

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// Range v3 library
//
//  Copyright Eric Niebler 2013-present
//
//  Use, modification and distribution is subject to the
//  Boost Software License, Version 1.0. (See accompanying
//  file LICENSE_1_0.txt or copy at
//  http://www.boost.org/LICENSE_1_0.txt)
//
// Project home: https://github.com/ericniebler/range-v3
//
 
#ifndef RANGES_V3_VIEW_TAKE_WHILE_HPP
#define RANGES_V3_VIEW_TAKE_WHILE_HPP
 
#include <type_traits>
#include <utility>
 
#include <meta/meta.hpp>
 
#include <range/v3/range_fwd.hpp>
 
#include <range/v3/functional/bind_back.hpp>
#include <range/v3/functional/compose.hpp>
#include <range/v3/functional/indirect.hpp>
#include <range/v3/functional/invoke.hpp>
#include <range/v3/iterator/concepts.hpp>
#include <range/v3/range/concepts.hpp>
#include <range/v3/utility/semiregular_box.hpp>
#include <range/v3/utility/static_const.hpp>
#include <range/v3/view/adaptor.hpp>
#include <range/v3/view/view.hpp>
 
#include <range/v3/detail/prologue.hpp>
 
namespace ranges
{
    template<typename Rng, typename Pred>
    struct iter_take_while_view
      : view_adaptor<iter_take_while_view<Rng, Pred>, Rng,
                     is_finite<Rng>::value ? finite : unknown>
    {
    private:
        friend range_access;
        RANGES_NO_UNIQUE_ADDRESS semiregular_box_t<Pred> pred_;
 
        template<bool IsConst>
        struct sentinel_adaptor : adaptor_base
        {
        private:
            friend struct sentinel_adaptor<!IsConst>;
            using CRng = meta::const_if_c<IsConst, Rng>;
            RANGES_NO_UNIQUE_ADDRESS semiregular_box_ref_or_val_t<Pred, IsConst> pred_;
 
        public:
            sentinel_adaptor() = default;
            sentinel_adaptor(semiregular_box_ref_or_val_t<Pred, IsConst> pred)
              : pred_(std::move(pred))
            {}
            template(bool Other)(
                requires IsConst AND CPP_NOT(Other)) //
                sentinel_adaptor(sentinel_adaptor<Other> that)
              : pred_(std::move(that.pred_))
            {}
            bool empty(iterator_t<CRng> const & it, sentinel_t<CRng> const & last) const
            {
                return it == last || !invoke(pred_, it);
            }
        };
        sentinel_adaptor<false> end_adaptor()
        {
            return {pred_};
        }
        template(bool Const = true)(
            requires Const AND range<meta::const_if_c<Const, Rng>> AND
                invocable<Pred const &, iterator_t<meta::const_if_c<Const, Rng>>>)
        sentinel_adaptor<Const> end_adaptor() const
        {
            return {pred_};
        }
 
    public:
        iter_take_while_view() = default;
        constexpr iter_take_while_view(Rng rng, Pred pred)
          : iter_take_while_view::view_adaptor{std::move(rng)}
          , pred_(std::move(pred))
        {}
    };
 
    template<typename Rng, typename Pred>
    struct take_while_view : iter_take_while_view<Rng, indirected<Pred>>
    {
        take_while_view() = default;
        constexpr take_while_view(Rng rng, Pred pred)
          : iter_take_while_view<Rng, indirected<Pred>>{std::move(rng),
                                                        indirect(std::move(pred))}
        {}
    };
 
#if RANGES_CXX_DEDUCTION_GUIDES >= RANGES_CXX_DEDUCTION_GUIDES_17
    template(typename Rng, typename Fun)(
        requires copy_constructible<Fun>)
    take_while_view(Rng &&, Fun)
        -> take_while_view<views::all_t<Rng>, Fun>;
#endif
 
    namespace views
    {
        struct iter_take_while_base_fn
        {
            template(typename Rng, typename Pred)(
                requires viewable_range<Rng> AND input_range<Rng> AND
                    predicate<Pred &, iterator_t<Rng>> AND copy_constructible<Pred>)
            constexpr iter_take_while_view<all_t<Rng>, Pred> //
            operator()(Rng && rng, Pred pred) const
            {
                return {all(static_cast<Rng &&>(rng)), std::move(pred)};
            }
        };
 
        struct iter_take_while_fn : iter_take_while_base_fn
        {
            using iter_take_while_base_fn::operator();
 
            template<typename Pred>
            constexpr auto operator()(Pred pred) const
            {
                return make_view_closure(
                    bind_back(iter_take_while_base_fn{}, std::move(pred)));
            }
        };
 
        struct take_while_base_fn
        {
            template(typename Rng, typename Pred)(
                requires viewable_range<Rng> AND input_range<Rng> AND
                    indirect_unary_predicate<Pred &, iterator_t<Rng>>)
            constexpr take_while_view<all_t<Rng>, Pred> //
            operator()(Rng && rng, Pred pred) const
            {
                return {all(static_cast<Rng &&>(rng)), std::move(pred)};
            }
            template(typename Rng, typename Pred, typename Proj)(
                requires viewable_range<Rng> AND input_range<Rng> AND
                    indirect_unary_predicate<composed<Pred, Proj> &, iterator_t<Rng>>)
            constexpr take_while_view<all_t<Rng>, composed<Pred, Proj>> //
            operator()(Rng && rng, Pred pred, Proj proj) const
            {
                return {all(static_cast<Rng &&>(rng)),
                        compose(std::move(pred), std::move(proj))};
            }
        };
 
        struct take_while_bind_fn
        {
            template<typename Pred>
            constexpr auto operator()(Pred pred) const // TODO: underconstrained
            {
                return make_view_closure(
                    bind_back(take_while_base_fn{}, std::move(pred)));
            }
            template(typename Pred, typename Proj)(
                requires (!range<Pred>)) // TODO: underconstrained
            constexpr auto operator()(Pred && pred, Proj proj) const
                                                          
            {
                return make_view_closure(bind_back(
                    take_while_base_fn{}, static_cast<Pred &&>(pred), std::move(proj)));
            }
        };
 
        struct RANGES_EMPTY_BASES take_while_fn
          : take_while_base_fn, take_while_bind_fn
        {
            using take_while_base_fn::operator();
            using take_while_bind_fn::operator();
        };

        RANGES_INLINE_VARIABLE(iter_take_while_fn, iter_take_while)
 
        
        RANGES_INLINE_VARIABLE(take_while_fn, take_while)
    } // namespace views
 
    namespace cpp20
    {
        namespace views
        {
            using ranges::views::take_while;
        }
        template(typename Rng, typename Pred)(
            requires viewable_range<Rng> AND input_range<Rng> AND
                predicate<Pred &, iterator_t<Rng>> AND copy_constructible<Pred>)
            using take_while_view = ranges::take_while_view<Rng, Pred>;
    } // namespace cpp20
} // namespace ranges
 
#include <range/v3/detail/epilogue.hpp>
#include <range/v3/detail/satisfy_boost_range.hpp>
RANGES_SATISFY_BOOST_RANGE(::ranges::iter_take_while_view)
RANGES_SATISFY_BOOST_RANGE(::ranges::take_while_view)
 
#endif