test/std/utilities/function.objects/unord.hash/enum.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++98, c++03, c++11

// <functional>

// make sure that we can hash enumeration values
// Not very portable

#include "test_macros.h"

#include <functional>
#include <cassert>
#include <type_traits>
#include <limits>

enum class Colors { red, orange, yellow, green, blue, indigo, violet };
enum class Cardinals { zero, one, two, three, five=5 };
enum class LongColors : short { red, orange, yellow, green, blue, indigo, violet };
enum class ShortColors : long { red, orange, yellow, green, blue, indigo, violet };
enum class EightBitColors : uint8_t { red, orange, yellow, green, blue, indigo, violet };

enum Fruits { apple, pear, grape, mango, cantaloupe };

template <class T>
void
test()
{
    typedef std::hash<T> H;
    static_assert((std::is_same<typename H::argument_type, T>::value), "" );
    static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
    ASSERT_NOEXCEPT(H()(T()));
    typedef typename std::underlying_type<T>::type under_type;

    H h1;
    std::hash<under_type> h2;
    for (int i = 0; i <= 5; ++i)
    {
        T t(static_cast<T> (i));
        const bool small = std::integral_constant<bool, sizeof(T) <= sizeof(std::size_t)>::value; // avoid compiler warnings
        if (small)
            assert(h1(t) == h2(static_cast<under_type>(i)));
    }
}

int main(int, char**)
{
    test<Cardinals>();

    test<Colors>();
    test<ShortColors>();
    test<LongColors>();
    test<EightBitColors>();

    test<Fruits>();

  return 0;
}