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

// Copyright (C) 2020-2025 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

// { dg-do run { target c++20 } }

#include <algorithm>
#include <functional>
#include <testsuite_hooks.h>
#include <testsuite_iterators.h>

using __gnu_test::test_container;
using __gnu_test::test_range;
using __gnu_test::input_iterator_wrapper;

namespace ranges = std::ranges;

struct X
{
  int i, j;
};

void
test01()
{
  VERIFY( ranges::max(1, 2) == 2);
  VERIFY( ranges::max(2, 1) == 2);
  VERIFY( ranges::max(1, 2, ranges::greater{}) == 1);
  VERIFY( ranges::max(1, 2, ranges::greater{}, std::negate<>{}) == 2);
  VERIFY( ranges::max(1, 2, {}, std::negate<>{}) == 1);
  VERIFY( ranges::max(X{1,2}, X{1,3}, {}, &X::i).j == 2 );
}

void
test02()
{
  int x[] = {1,2,3,4};
  do
    {
      test_range<int, input_iterator_wrapper> cx(x);
      VERIFY( ranges::max(cx) == 4 );
      cx.bounds.first = x;
      VERIFY( ranges::max(cx, ranges::greater{}) == 1 );
      cx.bounds.first = x;
      VERIFY( ranges::max(cx, {}, std::negate<>{}) == 1);
      cx.bounds.first = x;
      VERIFY( ranges::max(cx, ranges::greater{}, std::negate<>{}) == 4 );
    } while (ranges::next_permutation(x).found);

  constexpr X y[] = {{0,5},{1,2},{1,3}};
  static_assert(ranges::max(y, {}, &X::i).j == 2);
}

void
test03()
{
  VERIFY( ranges::max({2,3,1,4}) == 4 );
  VERIFY( ranges::max({2,3,1,4}, ranges::greater{}) == 1 );
  VERIFY( ranges::max({2,3,1,4}, {}, std::negate<>{}) == 1 );
  VERIFY( ranges::max({2,3,1,4}, ranges::greater{}, std::negate<>{}) == 4 );
}

void
test04()
{
  // PR libstdc++/112349 - ranges::max/min make unnecessary copies
  static int copies, moves;
  struct A {
    A(int m) : m(m) { }
    A(const A& other) : m(other.m) { ++copies; }
    A(A&& other) : m(other.m) { ++moves; }
    A& operator=(const A& other) { m = other.m; ++copies; return *this; }
    A& operator=(A&& other) { m = other.m; ++moves; return *this; }
    int m;
  };
  A r[5] = {5, 4, 3, 2, 1};
  (void)ranges::max(r, ranges::less{}, &A::m);
  VERIFY( copies == 1 );
  VERIFY( moves == 0 );
  copies = moves = 0;
  A s[5] = {1, 2, 3, 4, 5};
  (void)ranges::max(s, ranges::less{}, &A::m);
  VERIFY( copies == 5 );
  VERIFY( moves == 0 );
}

int
main()
{
  test01();
  test02();
  test03();
  test04();
}