ceph/src/boost/libs/hana/test/tuple/issue_90.cpp

   1 // Copyright Louis Dionne 2013-2016
   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/at.hpp>
   6 #include <boost/hana/at_key.hpp>
   7 #include <boost/hana/back.hpp>
   8 #include <boost/hana/front.hpp>
   9 #include <boost/hana/integral_constant.hpp>
  10 #include <boost/hana/tuple.hpp>
  11
  12 #include <utility>
  13 namespace hana = boost::hana;
  14
  15
  16 template <typename T>
  17 T const& cref(T& t) { return t; }
  18
  19 // a non-movable, non-copyable type
  20 struct RefOnly {
  21     RefOnly() = default;
  22     RefOnly(RefOnly const&) = delete;
  23     RefOnly(RefOnly&&) = delete;
  24 };
  25
  26 template <int i>
  27 struct RefOnly_i : hana::int_<i> {
  28     RefOnly_i() = default;
  29     RefOnly_i(RefOnly_i const&) = delete;
  30     RefOnly_i(RefOnly_i&&) = delete;
  31 };
  32
  33 int main() {
  34     hana::tuple<RefOnly> t;
  35
  36     // Make sure that we return the proper reference types from `at`.
  37     {
  38         RefOnly&& r1 = hana::at_c<0>(std::move(t));
  39         RefOnly& r2 = hana::at_c<0>(t);
  40         RefOnly const& r3 = hana::at_c<0>(cref(t));
  41
  42         (void)r1; (void)r2; (void)r3;
  43     }
  44
  45     // Make sure we return the proper reference types from `front`.
  46     {
  47         RefOnly&& r1 = hana::front(std::move(t));
  48         RefOnly& r2 = hana::front(t);
  49         RefOnly const& r3 = hana::front(cref(t));
  50
  51         (void)r1; (void)r2; (void)r3;
  52     }
  53
  54     // Make sure we return the proper reference types from `back`.
  55     {
  56         RefOnly&& r1 = hana::back(std::move(t));
  57         RefOnly& r2 = hana::back(t);
  58         RefOnly const& r3 = hana::back(cref(t));
  59
  60         (void)r1; (void)r2; (void)r3;
  61     }
  62
  63     // Make sure we return the proper reference types from `at_key`.
  64     {
  65         hana::tuple<RefOnly_i<3>> t{};
  66         RefOnly_i<3>& r1 = hana::at_key(t, RefOnly_i<3>{});
  67         RefOnly_i<3> const& r2 = hana::at_key(cref(t), RefOnly_i<3>{});
  68         RefOnly_i<3>&& r3 = hana::at_key(std::move(t), RefOnly_i<3>{});
  69
  70         (void)r1; (void)r2; (void)r3;
  71     }
  72 }