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

   1 // Copyright (C) 2020 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 = std::ranges::views;
  31
  32 void
  33 test01()
  34 {
  35   int x[] = {1,2,3,4,5,6};
  36   auto is_odd = [] (int i) { return i%2==1; };
  37   auto v = x | views::filter(is_odd);
  38   using R = decltype(v);
  39   static_assert(std::same_as<int&, decltype(*v.begin())>);
  40   static_assert(ranges::view<R>);
  41   static_assert(ranges::input_range<R>);
  42   static_assert(ranges::common_range<R>);
  43   static_assert(!ranges::sized_range<R>);
  44   static_assert(ranges::bidirectional_range<R>);
  45   static_assert(!ranges::random_access_range<R>);
  46   static_assert(ranges::range<views::all_t<R>>);
  47   VERIFY( ranges::equal(v, (int[]){1,3,5}) );
  48   VERIFY( ranges::equal(v | views::reverse, (int[]){5,3,1}) );
  49   VERIFY( v.pred()(3) == true );
  50   VERIFY( v.pred()(4) == false );
  51 }
  52
  53 void
  54 test02()
  55 {
  56   int x[] = {1,2,3,4,5,6};
  57   auto f = [flag=false] (int) mutable { return flag = !flag; };
  58   auto v = views::filter(f)(x);
  59   using R = decltype(v);
  60   static_assert(std::same_as<int&, decltype(*v.begin())>);
  61   static_assert(ranges::range<R>);
  62   static_assert(std::copyable<R>);
  63   static_assert(!ranges::view<const R>);
  64   VERIFY( ranges::equal(v, (int[]){1,3,5}) );
  65 }
  66
  67 struct X
  68 {
  69   int i, j;
  70 };
  71
  72 void
  73 test03()
  74 {
  75   X x[] = {{1,3}, {2,5}, {3,7}, {4,9}};
  76   test_range<X, bidirectional_iterator_wrapper> rx(x);
  77   auto v = rx | views::filter([] (auto&& p) { return p.i%2==0; });
  78   int sum = 0;
  79   for (auto i = v.begin(); i != v.end(); ++i)
  80     sum += i->j;
  81   VERIFY( sum == 14 );
  82 }
  83
  84 void
  85 test04()
  86 {
  87   auto yes = [] (int) { return true; };
  88   VERIFY( ranges::equal(views::iota(0) | views::filter(yes) | views::take(1),
  89                         (int[]){0}) );
  90 }
  91
  92 int
  93 main()
  94 {
  95   test01();
  96   test02();
  97   test03();
  98   test04();
  99 }