1 // Copyright Louis Dionne 2013-2017
2 // Distributed under the Boost Software License, Version 1.0.
3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
4
5 #include <boost/hana/assert.hpp>
6 #include <boost/hana/at.hpp>
7 #include <boost/hana/fold_right.hpp>
8 #include <boost/hana/tuple.hpp>
9 namespace hana = boost::hana;
10
11 //
12 // Make sure that we can fold_right and take arguments by reference.
13 //
14
main()15 int main() {
16 // with state
17 {
18 auto xs = hana::make_tuple(1, 2, 3);
19 int state = 99;
20
21 int& one = hana::fold_right(xs, state, [](int& i, int&) -> int& {
22 return i;
23 });
24 BOOST_HANA_RUNTIME_CHECK(one == 1);
25 one = 10;
26 BOOST_HANA_RUNTIME_CHECK(hana::at_c<0>(xs) == 10);
27 }
28
29 // without state
30 {
31 auto xs = hana::make_tuple(1, 2, 3);
32 int& one = hana::fold_right(xs, [](int& i, int&) -> int& {
33 return i;
34 });
35 BOOST_HANA_RUNTIME_CHECK(one == 1);
36 one = 10;
37 BOOST_HANA_RUNTIME_CHECK(hana::at_c<0>(xs) == 10);
38 }
39 }
40