/*
@copyright Louis Dionne 2014
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
 */

#include <boost/hana/map.hpp>

#include <boost/hana/detail/constexpr.hpp>
#include <boost/hana/detail/static_assert.hpp>
#include <boost/hana/integral.hpp>
#include <boost/hana/maybe.hpp>
#include <boost/hana/pair/instance.hpp>
using namespace boost::hana;


template <int i>
constexpr auto key = int_<i>;

template <int i>
constexpr auto value = int_<i + 100>;

template <int i, int j>
BOOST_HANA_CONSTEXPR_LAMBDA auto p = pair(key<i>, value<j>);

BOOST_HANA_CONSTEXPR_LAMBDA auto is = [](auto x) {
    return [=](auto y) { return equal(x, y); };
};

int main() {
    BOOST_HANA_STATIC_ASSERT(find(is(key<1>), map()) == nothing);

    BOOST_HANA_STATIC_ASSERT(find(is(key<1>), map(p<1, 1>)) == just(value<1>));
    BOOST_HANA_STATIC_ASSERT(find(is(key<2>), map(p<1, 1>)) == nothing);

    BOOST_HANA_STATIC_ASSERT(find(is(key<1>), map(p<1, 1>, p<2, 2>)) == just(value<1>));
    BOOST_HANA_STATIC_ASSERT(find(is(key<2>), map(p<1, 1>, p<2, 2>)) == just(value<2>));
    BOOST_HANA_STATIC_ASSERT(find(is(key<3>), map(p<1, 1>, p<2, 2>)) == nothing);
}