libstdc++-v3/testsuite/std/ranges/p2259.cc

   1 // Copyright (C) 2021-2024 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
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   5 // terms of the GNU General Public License as published by the
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   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-do compile { target c++20 } }
  19
  20 // Verify P2259 changes.
  21
  22 #include <ranges>
  23 #include <tuple>
  24 #include <vector>
  25
  26 namespace ranges = std::ranges;
  27 namespace views = std::views;
  28
  29 using std::__detail::__iter_without_category;
  30
  31 template<typename _Range>
  32 concept only_cxx20_input_range = ranges::input_range<_Range>
  33   && !ranges::forward_range<_Range>
  34   && __iter_without_category<ranges::iterator_t<_Range>>;
  35
  36 void
  37 test01()
  38 {
  39   extern std::vector<int> vec;
  40   only_cxx20_input_range auto v0
  41     = vec
  42     | views::transform([](int c) { return views::single(c); })
  43     | views::join;
  44
  45   // Verify the changes to filter_view.
  46   only_cxx20_input_range auto v1 = v0 | views::filter([](int c) { return c > 0; });
  47
  48   // Verify the changes to transform_view.
  49   only_cxx20_input_range auto v2 = v0 | views::transform([](int& c) -> auto& { return c; });
  50
  51   // Verify the changes to lazy_split_view.
  52   only_cxx20_input_range auto v3 = v0 | views::lazy_split(12);
  53   static_assert(only_cxx20_input_range<decltype(*v3.begin())>);
  54
  55   // Verify the changes to join_view.
  56   only_cxx20_input_range auto v4 = v0 | views::lazy_split(12) | views::join;
  57
  58   // Verify the changes to elements_view.
  59   only_cxx20_input_range auto v5
  60     = v0
  61     | views::transform([](int c) { return std::make_tuple(c, c); })
  62     | views::elements<0>;
  63
  64   // Verify the changes to common_iterator.
  65   only_cxx20_input_range auto v6 = v0 | views::common;
  66   (void) *(v6.begin()++);
  67
  68   // Verify the changes to iota_view.
  69   only_cxx20_input_range auto v8 = ranges::iota_view{v0.begin()};
  70
  71   // Verify the changes to move_iterator.
  72   __iter_without_category auto i9 = std::make_move_iterator(v0.begin());
  73
  74   // Verify the changes to counted_iterator.
  75   extern std::counted_iterator<int*> i10;
  76   static_assert(std::contiguous_iterator<decltype(i10)>);
  77   static_assert(std::same_as<std::iterator_traits<decltype(i10)>::iterator_category,
  78                              std::random_access_iterator_tag>);
  79   (void) i10.operator->();
  80   __iter_without_category auto i11 = std::counted_iterator{v0.begin(), 5};
  81 }
  82
  83 void
  84 test02()
  85 {
  86   // Verify LWG 3291 example.
  87   auto v = views::iota(0);
  88   auto i = std::counted_iterator{v.begin(), 5};
  89   static_assert(std::random_access_iterator<decltype(i)>);
  90 }