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

   1 // Copyright (C) 2020-2023 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 run { target c++2a } }
  20
  21 #include <algorithm>
  22 #include <forward_list>
  23 #include <ranges>
  24 #include <testsuite_hooks.h>
  25 #include <testsuite_iterators.h>
  26
  27 using __gnu_test::test_range;
  28 using __gnu_test::forward_iterator_wrapper;
  29
  30 namespace ranges = std::ranges;
  31 namespace views = std::ranges::views;
  32
  33 void
  34 test01()
  35 {
  36   auto p = [] (int i) { return i != 16; };
  37   auto v = views::iota(10) | views::take_while(p);
  38   VERIFY( ranges::equal(v, (int[]){10,11,12,13,14,15}) );
  39   using R = decltype(v);
  40   static_assert(ranges::view<R>);
  41   static_assert(!ranges::common_range<R>);
  42   static_assert(ranges::random_access_range<R>);
  43 }
  44
  45 void
  46 test02()
  47 {
  48   int x[] = {1,2,3,4,5};
  49   test_range<int, forward_iterator_wrapper> rx(x);
  50   auto v = rx | views::take_while([] (int i) { return i<4; });
  51   VERIFY( ranges::equal(v, (int[]){1,2,3}) );
  52   using R = decltype(v);
  53   static_assert(ranges::view<R>);
  54   static_assert(!ranges::common_range<R>);
  55   static_assert(ranges::forward_range<R>);
  56 }
  57
  58 void
  59 test03()
  60 {
  61   std::forward_list<int> x = {1,2,3,4,5};
  62   auto v
  63     = x | views::transform(std::negate{}) | views::take_while(std::identity{});
  64
  65   // Verify that _Sentinel<false> is implicitly convertible to _Sentinel<true>.
  66   static_assert(!ranges::common_range<decltype(v)>);
  67   static_assert(!std::same_as<decltype(ranges::end(v)),
  68                               decltype(ranges::cend(v))>);
  69   auto b = ranges::cend(v);
  70   b = ranges::end(v);
  71 }
  72
  73 void
  74 test04()
  75 {
  76   // LWG 3450
  77   auto v = views::single(1) | views::take_while([](int& x) { return true;});
  78   static_assert(ranges::range<decltype(v)>);
  79   static_assert(!ranges::range<decltype(v) const>);
  80 }
  81
  82 template<auto take_while = views::take_while>
  83 void
  84 test05()
  85 {
  86   // Verify SFINAE behavior.
  87   extern int x[5];
  88   auto p = [] (int*) { return true; };
  89   static_assert(!requires { take_while(); });
  90   static_assert(!requires { take_while(x, p, p); });
  91   static_assert(!requires { take_while(x, p); });
  92   static_assert(!requires { take_while(p)(x); });
  93   static_assert(!requires { x | (take_while(p) | views::all); });
  94   static_assert(!requires { (take_while(p) | views::all)(x); });
  95   static_assert(!requires { take_while | views::all; });
  96   static_assert(!requires { views::all | take_while; });
  97 }
  98
  99 int
 100 main()
 101 {
 102   test01();
 103   test02();
 104   test03();
 105   test04();
 106   test05();
 107 }