2021-10-05 21:37:46 +02:00

87 lines
2.7 KiB
C++

// Copyright Louis Dionne 2013-2017
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
#ifndef BOOST_HANA_TEST_LAWS_MONOID_HPP
#define BOOST_HANA_TEST_LAWS_MONOID_HPP
#include <boost/hana/assert.hpp>
#include <boost/hana/bool.hpp>
#include <boost/hana/concept/comparable.hpp>
#include <boost/hana/core/when.hpp>
#include <boost/hana/functional/capture.hpp>
#include <boost/hana/lazy.hpp>
#include <boost/hana/concept/monoid.hpp>
#include <laws/base.hpp>
namespace boost { namespace hana { namespace test {
template <typename M, typename = when<true>>
struct TestMonoid : TestMonoid<M, laws> {
using TestMonoid<M, laws>::TestMonoid;
};
template <typename M>
struct TestMonoid<M, laws> {
template <typename Xs>
TestMonoid(Xs xs) {
#ifdef BOOST_HANA_WORKAROUND_MSVC_DECLTYPEAUTO_RETURNTYPE_662735
zero<M>(); // force adding zero<M>'s member function to pending temploid list
#endif
hana::for_each(xs, hana::capture(xs)([](auto xs, auto a) {
static_assert(Monoid<decltype(a)>{}, "");
// left identity
BOOST_HANA_CHECK(hana::equal(
hana::plus(zero<M>(), a),
a
));
// right identity
BOOST_HANA_CHECK(hana::equal(
hana::plus(a, zero<M>()),
a
));
hana::for_each(xs,
hana::capture(xs, a)([](auto xs, auto a, auto b) {
hana::for_each(xs,
hana::capture(a, b)([](auto a, auto b, auto c) {
// associativity
BOOST_HANA_CHECK(equal(
hana::plus(a, hana::plus(b, c)),
hana::plus(hana::plus(a, b), c)
));
}));
}));
}));
}
};
template <typename C>
struct TestMonoid<C, when<Constant<C>::value>>
: TestMonoid<C, laws>
{
template <typename Xs>
TestMonoid(Xs xs) : TestMonoid<C, laws>{xs} {
BOOST_HANA_CHECK(hana::equal(
hana::value(zero<C>()),
zero<typename C::value_type>()
));
foreach2(xs, [](auto x, auto y) {
BOOST_HANA_CHECK(hana::equal(
hana::plus(hana::value(x), hana::value(y)),
hana::value(hana::plus(x, y))
));
});
}
};
}}} // end namespace boost::hana::test
#endif // !BOOST_HANA_TEST_LAWS_MONOID_HPP