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

   1 // Copyright (C) 2021-2023 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   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-options "-std=gnu++2a" }
  19 // { dg-do compile { target c++2a } }
  20
  21 // Verify P2259 changes.
  22
  23 #include <ranges>
  24 #include <tuple>
  25 #include <vector>
  26
  27 namespace ranges = std::ranges;
  28 namespace views = std::views;
  29
  30 using std::__detail::__iter_without_category;
  31
  32 template<typename _Range>
  33 concept only_cxx20_input_range = ranges::input_range<_Range>
  34   && !ranges::forward_range<_Range>
  35   && __iter_without_category<ranges::iterator_t<_Range>>;
  36
  37 void
  38 test01()
  39 {
  40   extern std::vector<int> vec;
  41   only_cxx20_input_range auto v0
  42     = vec
  43     | views::transform([](int c) { return views::single(c); })
  44     | views::join;
  45
  46   // Verify the changes to filter_view.
  47   only_cxx20_input_range auto v1 = v0 | views::filter([](int c) { return c > 0; });
  48
  49   // Verify the changes to transform_view.
  50   only_cxx20_input_range auto v2 = v0 | views::transform([](int& c) -> auto& { return c; });
  51
  52   // Verify the changes to lazy_split_view.
  53   only_cxx20_input_range auto v3 = v0 | views::lazy_split(12);
  54   static_assert(only_cxx20_input_range<decltype(*v3.begin())>);
  55
  56   // Verify the changes to join_view.
  57   only_cxx20_input_range auto v4 = v0 | views::lazy_split(12) | views::join;
  58
  59   // Verify the changes to elements_view.
  60   only_cxx20_input_range auto v5
  61     = v0
  62     | views::transform([](int c) { return std::make_tuple(c, c); })
  63     | views::elements<0>;
  64
  65   // Verify the changes to common_iterator.
  66   only_cxx20_input_range auto v6 = v0 | views::common;
  67   (void) *(v6.begin()++);
  68
  69   // Verify the changes to iota_view.
  70   only_cxx20_input_range auto v8 = ranges::iota_view{v0.begin()};
  71
  72   // Verify the changes to move_iterator.
  73   __iter_without_category auto i9 = std::make_move_iterator(v0.begin());
  74
  75   // Verify the changes to counted_iterator.
  76   extern std::counted_iterator<int*> i10;
  77   static_assert(std::contiguous_iterator<decltype(i10)>);
  78   static_assert(std::same_as<std::iterator_traits<decltype(i10)>::iterator_category,
  79                              std::random_access_iterator_tag>);
  80   (void) i10.operator->();
  81   __iter_without_category auto i11 = std::counted_iterator{v0.begin(), 5};
  82 }
  83
  84 void
  85 test02()
  86 {
  87   // Verify LWG 3291 example.
  88   auto v = views::iota(0);
  89   auto i = std::counted_iterator{v.begin(), 5};
  90   static_assert(std::random_access_iterator<decltype(i)>);
  91 }