libstdc++-v3/testsuite/std/ranges/adaptors/reverse.cc

   1 // Copyright (C) 2020-2022 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 run { target c++2a } }
  20
  21 #include <algorithm>
  22 #include <ranges>
  23 #include <testsuite_hooks.h>
  24 #include <testsuite_iterators.h>
  25
  26 using __gnu_test::test_range;
  27 using __gnu_test::bidirectional_iterator_wrapper;
  28
  29 namespace ranges = std::ranges;
  30 namespace views = ranges::views;
  31
  32 void
  33 test01()
  34 {
  35   int x[] = {1,2,3,4,5};
  36   auto v = x | views::reverse;
  37   VERIFY( ranges::equal(v, (int[]){5,4,3,2,1}) );
  38   VERIFY( ranges::equal(v | views::reverse, x) );
  39   static_assert(ranges::view<decltype(v)>);
  40   static_assert(ranges::sized_range<decltype(v)>);
  41   static_assert(ranges::common_range<decltype(v)>);
  42   static_assert(ranges::random_access_range<decltype(v)>);
  43 }
  44
  45 void
  46 test02()
  47 {
  48   int x[] = {1,2,3,4,5};
  49   test_range<int, bidirectional_iterator_wrapper> rx(x);
  50   auto v = views::reverse(rx);
  51   VERIFY( ranges::equal(v, (int[]){5,4,3,2,1}) );
  52   VERIFY( ranges::equal(v | views::reverse, rx) );
  53   static_assert(ranges::view<decltype(v)>);
  54   static_assert(!ranges::sized_range<decltype(v)>);
  55   static_assert(ranges::common_range<decltype(v)>);
  56   static_assert(!ranges::random_access_range<decltype(v)>);
  57   static_assert(ranges::bidirectional_range<decltype(v)>);
  58 }
  59
  60 void
  61 test03()
  62 {
  63   int x[] = {1,7,3,6,5,2,4,8};
  64   auto is_even = [] (int i) { return i%2==0; };
  65   int sum = 0;
  66   for (auto i : x | views::reverse | views::filter(is_even))
  67     sum += i;
  68   VERIFY( sum == 20 );
  69 }
  70
  71 void
  72 test04()
  73 {
  74   int x[] = {1,2,3,4,5};
  75   VERIFY( ranges::equal(x | views::reverse | (views::reverse | views::reverse),
  76                         (int[]){5,4,3,2,1}) );
  77 }
  78
  79 // The following tests that reverse_view::begin caches its result.
  80
  81 template<typename T>
  82 struct test_wrapper : bidirectional_iterator_wrapper<T>
  83 {
  84   static inline int increment_count = 0;
  85
  86   using bidirectional_iterator_wrapper<T>::bidirectional_iterator_wrapper;
  87
  88   test_wrapper() : bidirectional_iterator_wrapper<T>()
  89   { }
  90
  91   test_wrapper
  92   operator++(int)
  93   {
  94     auto tmp = *this;
  95     ++*this;
  96     return tmp;
  97   }
  98
  99   test_wrapper&
 100   operator++()
 101   {
 102     ++increment_count;
 103     bidirectional_iterator_wrapper<T>::operator++();
 104     return *this;
 105   }
 106
 107   test_wrapper
 108   operator--(int)
 109   {
 110     auto tmp = *this;
 111     --*this;
 112     return tmp;
 113   }
 114
 115   test_wrapper&
 116   operator--()
 117   {
 118     bidirectional_iterator_wrapper<T>::operator--();
 119     return *this;
 120   }
 121 };
 122
 123 void
 124 test05()
 125 {
 126   int x[] = {1,2,3,4,5};
 127   test_range<int, test_wrapper> rx(x);
 128   auto v = rx | views::reverse;
 129   VERIFY( ranges::equal(v, (int[]){5,4,3,2,1}) );
 130   VERIFY( ranges::equal(v, (int[]){5,4,3,2,1}) );
 131   VERIFY( test_wrapper<int>::increment_count == 5 );
 132 }
 133
 134 namespace test_ns
 135 {
 136   struct A {};
 137   template <typename T>
 138   void make_reverse_iterator(T&&) {}
 139 } // namespace test_ns
 140
 141 void
 142 test06()
 143 {
 144   // Check that views::reverse works and does not use ADL which could lead
 145   // to accidentally finding test_ns::make_reverse_iterator(A*).
 146   test_ns::A as[] = {{}, {}};
 147   auto v = as | std::views::reverse;
 148   using V = decltype(v);
 149   static_assert( std::ranges::view<V> );
 150   static_assert( std::ranges::range<const V> );
 151 }
 152
 153 template<auto reverse = views::reverse>
 154 void
 155 test07()
 156 {
 157   // Verify SFINAE behavior.
 158   static_assert(!requires { reverse(); });
 159   static_assert(!requires { reverse(0, 0); });
 160   static_assert(!requires { reverse(0); });
 161   static_assert(!requires { 0 | reverse; });
 162 }
 163
 164 void
 165 test08()
 166 {
 167   // PR libstdc++/100639
 168   auto v = views::iota(1701ll, 3000ll) | views::reverse | views::take(5);
 169   for (auto x : v)
 170     ;
 171 }
 172
 173 int
 174 main()
 175 {
 176   test01();
 177   test02();
 178   test03();
 179   test04();
 180   test05();
 181   test06();
 182   test07();
 183   test08();
 184 }