libstdc++-v3/testsuite/25_algorithms/minmax_element/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 <functional>
  22 #include <testsuite_hooks.h>
  23 #include <testsuite_iterators.h>
  24
  25 using __gnu_test::test_container;
  26 using __gnu_test::test_range;
  27 using __gnu_test::forward_iterator_wrapper;
  28
  29 namespace ranges = std::ranges;
  30
  31 struct X
  32 {
  33   int i, j;
  34 };
  35
  36 void
  37 test01()
  38 {
  39   int x[] = {1,2,3,4};
  40   do
  41     {
  42       test_range<int, forward_iterator_wrapper> cx(x);
  43       VERIFY( *ranges::minmax_element(cx).min == 1 );
  44       VERIFY( *ranges::minmax_element(cx).max == 4 );
  45       VERIFY( *ranges::minmax_element(cx, ranges::greater{}).min == 4 );
  46       VERIFY( *ranges::minmax_element(cx, ranges::greater{}).max == 1 );
  47       VERIFY( *ranges::minmax_element(cx, {}, std::negate<>{}).min == 4);
  48       VERIFY( *ranges::minmax_element(cx, {}, std::negate<>{}).max == 1);
  49       VERIFY( *ranges::minmax_element(cx, ranges::greater{}, std::negate<>{}).min
  50               == 1 );
  51       VERIFY( *ranges::minmax_element(cx, ranges::greater{}, std::negate<>{}).max
  52               == 4 );
  53     } while (ranges::next_permutation(x).found);
  54
  55   test_container<int, forward_iterator_wrapper> cx(x);
  56   VERIFY( ranges::minmax_element(cx.begin(), cx.begin()).min == cx.begin() );
  57   VERIFY( ranges::minmax_element(cx.begin(), cx.begin()).max == cx.begin() );
  58
  59   constexpr X y[] = {{1,5},{1,2},{1,3}};
  60   static_assert(ranges::minmax_element(y, y+3, {}, &X::i).min->j == 5);
  61   static_assert(ranges::minmax_element(y, y+3, {}, &X::i).max->j == 3);
  62 }
  63
  64 void
  65 test02()
  66 {
  67   // Verify we perform at most 3*N/2 applications of the comparison predicate.
  68   static int counter;
  69   struct counted_less
  70   { bool operator()(int a, int b) { ++counter; return a < b; } };
  71
  72   int x[] = {1,2,3,4,5,6,7,8,9,10};
  73   ranges::minmax_element(x, x+2, counted_less{});
  74   VERIFY( counter == 1 );
  75
  76   counter = 0;
  77   ranges::minmax_element(x, x+3, counted_less{});
  78   VERIFY( counter == 3 );
  79
  80   counter = 0;
  81   ranges::minmax_element(x, counted_less{});
  82   VERIFY( counter <= 15 );
  83
  84   ranges::reverse(x);
  85   counter = 0;
  86   ranges::minmax_element(x, counted_less{});
  87   VERIFY( counter <= 15 );
  88 }
  89
  90 int
  91 main()
  92 {
  93   test01();
  94   test02();
  95 }