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- // 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)
- #include <boost/hana/assert.hpp>
- #include <boost/hana/at.hpp>
- #include <boost/hana/fold_left.hpp>
- #include <boost/hana/tuple.hpp>
- namespace hana = boost::hana;
- //
- // Make sure that we can fold_left and take arguments by reference.
- //
- int main() {
- // with state
- {
- auto xs = hana::make_tuple(1, 2, 3);
- int state = 99;
- int& three = hana::fold_left(xs, state, [](int&, int& i) -> int& {
- return i;
- });
- BOOST_HANA_RUNTIME_CHECK(three == 3);
- three = 10;
- BOOST_HANA_RUNTIME_CHECK(hana::at_c<2>(xs) == 10);
- }
- // without state
- {
- auto xs = hana::make_tuple(1, 2, 3);
- int& three = hana::fold_left(xs, [](int&, int& i) -> int& {
- return i;
- });
- BOOST_HANA_RUNTIME_CHECK(three == 3);
- three = 10;
- BOOST_HANA_RUNTIME_CHECK(hana::at_c<2>(xs) == 10);
- }
- }
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