2
0
mirror of https://github.com/boostorg/hana.git synced 2026-01-24 18:02:19 +00:00
Files
hana/example/list/traversable.cpp
2015-02-01 21:02:18 -05:00

56 lines
1.3 KiB
C++

/*
@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/assert.hpp>
#include <boost/hana/integral_constant.hpp>
#include <boost/hana/maybe.hpp>
#include <boost/hana/tuple.hpp>
#include <string>
using namespace boost::hana;
int main() {
//! [main]
using namespace std::string_literals;
BOOST_HANA_RUNTIME_CHECK(
sequence<Tuple>(
tuple(tuple("a1"s, "a2"s), tuple("b1"s), tuple("c1"s, "c2"s, "c3"s))
)
==
tuple(
tuple("a1"s, "b1"s, "c1"s),
tuple("a1"s, "b1"s, "c2"s),
tuple("a1"s, "b1"s, "c3"s),
tuple("a2"s, "b1"s, "c1"s),
tuple("a2"s, "b1"s, "c2"s),
tuple("a2"s, "b1"s, "c3"s)
)
);
BOOST_HANA_CONSTEXPR_LAMBDA auto half = [](auto x) {
return if_(x % int_<2> == int_<0>,
just(x / int_<2>),
nothing
);
};
BOOST_HANA_CONSTANT_CHECK(
traverse<Maybe>(tuple(int_<2>, int_<4>, int_<6>), half)
==
just(tuple(int_<1>, int_<2>, int_<3>))
);
BOOST_HANA_CONSTANT_CHECK(
traverse<Maybe>(tuple(int_<2>, int_<3>, int_<6>), half)
==
nothing
);
//! [main]
}