/*=============================================================================
    Copyright (c) 2017 Paul Fultz II
    fold.cpp
    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)
==============================================================================*/
#include <boost/hof/fold.hpp>
#include "test.hpp"

struct max_f
{
    template<class T, class U>
    constexpr T operator()(T x, U y) const noexcept
    {
        return x > y ? x : y;
    }
};

struct sum_f
{
    template<class T, class U>
    constexpr T operator()(T x, U y) const BOOST_HOF_RETURNS_DEDUCE_NOEXCEPT(x+y)
    {
        return x + y;
    }
};

#if BOOST_HOF_HAS_NOEXCEPT_DEDUCTION
BOOST_HOF_TEST_CASE()
{
    static_assert(noexcept(boost::hof::fold(max_f(), 0)(2, 3, 4, 5)), "noexcept fold");
    static_assert(noexcept(boost::hof::fold(sum_f(), 0)(2, 3, 4, 5)), "noexcept fold");
    static_assert(!noexcept(boost::hof::fold(sum_f(), std::string())("hello", "-", "world")), "noexcept fold");
}
#endif

BOOST_HOF_TEST_CASE()
{
    BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f(), 0)(2, 3, 4, 5) == 5);
    BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f(), 0)(5, 4, 3, 2) == 5);
    BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f(), 0)(2, 3, 5, 4) == 5);

    BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f(), 0)(2, 3, 4, 5) == 5);
    BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f(), 0)(5, 4, 3, 2) == 5);
    BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f(), 0)(2, 3, 5, 4) == 5);
}

BOOST_HOF_TEST_CASE()
{
    BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f(), 0)() == 0);
    BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f(), 0)(5) == 5);

    BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f(), 0)() == 0);
    BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f(), 0)(5) == 5);
}

template<class... Ts>
constexpr auto find_positive_max(Ts... xs) BOOST_HOF_RETURNS
(
    boost::hof::fold(max_f(), 0)(xs...)
);

BOOST_HOF_TEST_CASE()
{
    BOOST_HOF_TEST_CHECK(find_positive_max() == 0);
    BOOST_HOF_TEST_CHECK(find_positive_max(5) == 5);

    BOOST_HOF_STATIC_TEST_CHECK(find_positive_max() == 0);
    BOOST_HOF_STATIC_TEST_CHECK(find_positive_max(5) == 5);
}

BOOST_HOF_TEST_CASE()
{
    BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f())(5) == 5);

    BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f())(5) == 5);
}

BOOST_HOF_TEST_CASE()
{
    BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f())(2, 3, 4, 5) == 5);
    BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f())(5, 4, 3, 2) == 5);
    BOOST_HOF_TEST_CHECK(boost::hof::fold(max_f())(2, 3, 5, 4) == 5);

    BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f())(2, 3, 4, 5) == 5);
    BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f())(5, 4, 3, 2) == 5);
    BOOST_HOF_STATIC_TEST_CHECK(boost::hof::fold(max_f())(2, 3, 5, 4) == 5);
}

BOOST_HOF_TEST_CASE()
{
    BOOST_HOF_TEST_CHECK(boost::hof::fold(sum_f(), std::string())("hello", "-", "world") == "hello-world");
}