TLA  Line data    Source code

       1                 : //
       2                 : // Copyright (c) 2026 Steve Gerbino
       3                 : //
       4                 : // Distributed under the Boost Software License, Version 1.0. (See accompanying
       5                 : // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       6                 : //
       7                 : // Official repository: https://github.com/cppalliance/capy
       8                 : //
       9                 : 
      10                 : #ifndef BOOST_CAPY_DETAIL_OWNED_RANGE_HPP
      11                 : #define BOOST_CAPY_DETAIL_OWNED_RANGE_HPP
      12                 : 
      13                 : #include <boost/capy/detail/config.hpp>
      14                 : 
      15                 : #include <ranges>
      16                 : #include <type_traits>
      17                 : #include <utility>
      18                 : #include <vector>
      19                 : 
      20                 : namespace boost {
      21                 : namespace capy {
      22                 : namespace detail {
      23                 : 
      24                 : // A join's runners refer to their awaitables in place until they start,
      25                 : // so the range it owns must yield lvalues that outlive the iteration.
      26                 : // Only a forward range guarantees that: an input iterator may hold the
      27                 : // element it yields and replace it on the next step. Any other range is
      28                 : // moved into a vector instead.
      29                 : template<class R>
      30                 : using owned_range_t = std::conditional_t<
      31                 :     std::ranges::forward_range<std::remove_cvref_t<R>&> &&
      32                 :     std::is_lvalue_reference_v<
      33                 :         std::ranges::range_reference_t<std::remove_cvref_t<R>&>>,
      34                 :     std::remove_cvref_t<R>,
      35                 :     std::vector<std::ranges::range_value_t<R>>>;
      36                 : 
      37                 : template<class R>
      38                 : owned_range_t<R>
      39 HIT          41 : own_range(R&& r)
      40                 : {
      41                 :     if constexpr(std::is_same_v<owned_range_t<R>, std::remove_cvref_t<R>>)
      42                 :     {
      43              36 :         return std::forward<R>(r);
      44                 :     }
      45                 :     else
      46                 :     {
      47               5 :         owned_range_t<R> v;
      48               5 :         v.reserve(std::ranges::size(r));
      49              34 :         for(auto&& a : r)
      50              13 :             v.push_back(std::move(a));
      51               8 :         return v;
      52               5 :     }
      53                 : }
      54                 : 
      55                 : } // namespace detail
      56                 : } // namespace capy
      57                 : } // namespace boost
      58                 : 
      59                 : #endif