libstdc++-v3/testsuite/25_algorithms/next_permutation/constrained.cc

   1 // Copyright (C) 2020-2025 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-do run { target c++20 } }
  19
  20 #include <algorithm>
  21 #include <testsuite_hooks.h>
  22 #include <testsuite_iterators.h>
  23
  24 using __gnu_test::test_container;
  25 using __gnu_test::test_range;
  26 using __gnu_test::bidirectional_iterator_wrapper;
  27
  28 namespace ranges = std::ranges;
  29
  30 void
  31 test01()
  32 {
  33   int x[] = {1, 2, 3, 4, 5};
  34   int y[] = {1, 2, 3, 4, 5};
  35
  36   for (int i = 0; i <= 5; i++)
  37     {
  38       test_container<int, bidirectional_iterator_wrapper> cx(x, x+i);
  39       test_container<int, bidirectional_iterator_wrapper> cy(y, y+i);
  40       for (int j = 0; ; j++)
  41         {
  42           auto found1 = std::next_permutation(cx.begin(), cx.end());
  43           auto [last,found2] = ranges::next_permutation(cy.begin(), cy.end());
  44           VERIFY( found1 == found2 );
  45           VERIFY( ranges::equal(cx, cy) );
  46           if (!found2)
  47             break;
  48         }
  49     }
  50 }
  51
  52 void
  53 test02()
  54 {
  55   int x[] = {5, 4, 3, 2, 1};
  56   test_range<int, bidirectional_iterator_wrapper> rx(x);
  57   auto [last,found] = ranges::next_permutation(rx, ranges::greater{});
  58   VERIFY( found && last == rx.end() );
  59   VERIFY( last == rx.end() );
  60   VERIFY( ranges::equal(rx, (int[]){5,4,3,1,2}) );
  61   ranges::next_permutation(rx, {}, [] (int a) { return -a; });
  62   VERIFY( ranges::equal(rx, (int[]){5,4,2,3,1}) );
  63
  64   VERIFY( !ranges::next_permutation(x, x).found );
  65   VERIFY( !ranges::next_permutation(x, x+1).found );
  66 }
  67
  68 constexpr bool
  69 test03()
  70 {
  71   int x[] = {1,2,3};
  72   ranges::next_permutation(x);
  73   return ranges::equal(x, (int[]){1,3,2});
  74 }
  75
  76 int
  77 main()
  78 {
  79   test01();
  80   test02();
  81   static_assert(test03());
  82 }