libstdc++-v3/testsuite/std/ranges/istream_view.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 <sstream>
  24 #include <testsuite_hooks.h>
  25 #include <testsuite_iterators.h>
  26 #include <testsuite_rvalref.h>
  27
  28 namespace ranges = std::ranges;
  29 namespace views = std::views;
  30
  31 struct X : __gnu_test::rvalstruct
  32 {
  33   char c;
  34
  35   friend std::istream&
  36   operator>>(std::istream& is, X& m)
  37   {
  38     is >> m.c;
  39     return is;
  40   }
  41 };
  42
  43
  44 void
  45 test01()
  46 {
  47   std::string s = "0123456789";
  48   auto ss = std::istringstream{s};
  49   auto v = ranges::istream_view<X>(ss);
  50   VERIFY( ranges::equal(v, s, {}, &X::c) );
  51 }
  52
  53 void
  54 test02()
  55 {
  56   auto ints = std::istringstream{"0 1  2   3     4"};
  57   int x[5];
  58   ranges::copy(ranges::istream_view<int>(ints), x);
  59   VERIFY( ranges::equal(x, (int[]){0,1,2,3,4}) );
  60 }
  61
  62 void
  63 test03()
  64 {
  65   auto input = std::istringstream{"0 1 2 3 4 5 6 7 8 9"};
  66   auto small = [](const auto x) noexcept { return x < 5; };
  67   auto v = ranges::istream_view<int>(input) | views::take_while(small);
  68   VERIFY( ranges::equal(v, (int[]){0,1,2,3,4}) );
  69 }
  70
  71 template<typename T>
  72 concept has_iterator_category = requires { typename T::iterator_category; };
  73
  74 void
  75 test04()
  76 {
  77   std::istringstream s("12345");
  78   auto v = ranges::istream_view<char>(s);
  79   // LWG 3397
  80   using It = ranges::iterator_t<decltype(v)>;
  81   static_assert(!has_iterator_category<It>);
  82   static_assert(std::input_iterator<It>);
  83   static_assert(!std::forward_iterator<It>);
  84 }
  85
  86 void
  87 test05()
  88 {
  89   // PR libstdc++/101231
  90   auto words = std::istringstream{"42"};
  91   auto is = ranges::istream_view<int>(words);
  92   auto r = is | views::filter([](auto) { return true; });
  93   for (auto x : r)
  94     ;
  95 }
  96
  97 void
  98 test06()
  99 {
 100   // Default template argument
 101   using V = std::ranges::basic_istream_view<int, char>;
 102   using W = std::ranges::basic_istream_view<int, char, std::char_traits<char>>;
 103   static_assert( std::is_same_v<V, W> );
 104 }
 105
 106 void
 107 test07()
 108 {
 109   // P2432R1, views::istream
 110   auto nums = std::istringstream("0 1 2 3 4");
 111   ranges::istream_view<int> v(nums);
 112   int sum = 0;
 113   for (int val : views::istream<int>(nums))
 114     sum += val;
 115   VERIFY( sum == 10 );
 116 }
 117
 118 int
 119 main()
 120 {
 121   test01();
 122   test02();
 123   test03();
 124   test04();
 125   test05();
 126   test06();
 127   test07();
 128 }