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hana/example/tuple.cpp
2015-02-04 18:10:17 -05:00

64 lines
1.4 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/detail/constexpr.hpp>
#include <boost/hana/foldable.hpp>
#include <boost/hana/integral_constant.hpp>
#include <boost/hana/logical.hpp>
#include <boost/hana/sequence.hpp>
#include <boost/hana/tuple.hpp>
using namespace boost::hana;
int main() {
{
//! [tuple_c]
BOOST_HANA_CONSTANT_CHECK(
to<Tuple>(tuple_c<int, 0, 1, 2>)
==
tuple(int_<0>, int_<1>, int_<2>)
);
BOOST_HANA_CONSTANT_CHECK(head(tuple_c<int, 0, 1, 2>) == int_<0>);
//! [tuple_c]
}{
//! [Foldable]
using namespace literals;
constexpr auto numbers = tuple_c<int, 5, -1, 0, -7, -2, 0, -5, 4>;
constexpr auto negatives = tuple_c<int, -1, -7, -2, -5>;
BOOST_HANA_CONSTEXPR_LAMBDA auto keep_negatives = [](auto n, auto acc) {
return if_(n < 0_c, prepend(n, acc), acc);
};
BOOST_HANA_CONSTANT_CHECK(foldr(numbers, tuple_c<int>, keep_negatives) == negatives);
//! [Foldable]
}{
//! [Tuple_interop]
BOOST_HANA_CONSTEXPR_CHECK(
to<Tuple>(std::make_tuple(1, '2', 3.3)) == tuple(1, '2', 3.3)
);
BOOST_HANA_CONSTANT_CHECK(
to<Tuple>(range(int_<1>, int_<4>)) == tuple(int_<1>, int_<2>, int_<3>)
);
BOOST_HANA_CONSTEXPR_CHECK(
to<Tuple>(std::array<int, 3>{{1, 2, 3}}) == tuple(1, 2, 3)
);
//! [Tuple_interop]
}
}