boost_beast/test/core/get_lowest_layer.cpp

//
// Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

// Test that header file is self-contained.
#include <beast/core/detail/get_lowest_layer.hpp>

#include <type_traits>

namespace beast {
namespace detail {

struct F1
{
};

struct F2
{
};

template<class F>
struct F3
{
    using next_layer_type =
        typename std::remove_reference<F>::type;

    using lowest_layer_type = typename
        get_lowest_layer<next_layer_type>::type;
};

template<class F>
struct F4
{
    using next_layer_type =
        typename std::remove_reference<F>::type;

    using lowest_layer_type = typename
        get_lowest_layer<next_layer_type>::type;
};

static_assert(! has_lowest_layer<F1>::value, "");
static_assert(! has_lowest_layer<F2>::value, "");
static_assert(has_lowest_layer<F3<F1>>::value, "");
static_assert(has_lowest_layer<F4<F3<F2>>>::value, "");

static_assert(std::is_same<
    get_lowest_layer<F1>::type, F1>::value, "");

static_assert(std::is_same<
    get_lowest_layer<F2>::type, F2>::value, "");

static_assert(std::is_same<
    get_lowest_layer<F3<F1>>::type, F1>::value, "");

static_assert(std::is_same<
    get_lowest_layer<F3<F2>>::type, F2>::value, "");

static_assert(std::is_same<
    get_lowest_layer<F4<F1>>::type, F1>::value, "");

static_assert(std::is_same<
    get_lowest_layer<F4<F2>>::type, F2>::value, "");

static_assert(std::is_same<
    get_lowest_layer<F4<F3<F1>>>::type, F1>::value, "");

static_assert(std::is_same<
    get_lowest_layer<F4<F3<F2>>>::type, F2>::value, "");

} // detail
} // beast