ceph/src/boost/libs/hana/test/map/at_key.ref.cpp

   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_key.hpp>
   7 #include <boost/hana/integral_constant.hpp>
   8 #include <boost/hana/map.hpp>
   9 #include <boost/hana/pair.hpp>
  10
  11 #include <utility>
  12 namespace hana = boost::hana;
  13
  14
  15 template <typename T>
  16 T const& cref(T& t) { return t; }
  17
  18 int main() {
  19     // using at_key
  20     {
  21         auto xs = hana::make_map(
  22             hana::make_pair(hana::int_c<0>, 0),
  23             hana::make_pair(hana::int_c<1>, '1'),
  24             hana::make_pair(hana::int_c<2>, 2.2)
  25         );
  26
  27         // Make sure we return lvalue-references
  28         BOOST_HANA_RUNTIME_CHECK(hana::at_key(xs, hana::int_c<0>) == 0);
  29         BOOST_HANA_RUNTIME_CHECK(hana::at_key(xs, hana::int_c<1>) == '1');
  30         BOOST_HANA_RUNTIME_CHECK(hana::at_key(xs, hana::int_c<2>) == 2.2);
  31
  32         int& a = hana::at_key(xs, hana::int_c<0>);
  33         char& b = hana::at_key(xs, hana::int_c<1>);
  34         double& c = hana::at_key(xs, hana::int_c<2>);
  35         a = 9;
  36         b = '9';
  37         c = 9.9;
  38
  39         // Make sure we return lvalue-references to const on a const map
  40         int const& ca = hana::at_key(cref(xs), hana::int_c<0>);
  41         char const& cb = hana::at_key(cref(xs), hana::int_c<1>);
  42         double const& cc = hana::at_key(cref(xs), hana::int_c<2>);
  43
  44         BOOST_HANA_RUNTIME_CHECK(ca == 9);
  45         BOOST_HANA_RUNTIME_CHECK(cb == '9');
  46         BOOST_HANA_RUNTIME_CHECK(cc == 9.9);
  47     }
  48
  49     // using operator[]
  50     {
  51         auto xs = hana::make_map(
  52             hana::make_pair(hana::int_c<0>, 0),
  53             hana::make_pair(hana::int_c<1>, '1'),
  54             hana::make_pair(hana::int_c<2>, 2.2)
  55         );
  56
  57         BOOST_HANA_RUNTIME_CHECK(xs[hana::int_c<0>] == 0);
  58         BOOST_HANA_RUNTIME_CHECK(xs[hana::int_c<1>] == '1');
  59         BOOST_HANA_RUNTIME_CHECK(xs[hana::int_c<2>] == 2.2);
  60
  61         xs[hana::int_c<0>] = 9;
  62         xs[hana::int_c<1>] = '9';
  63         xs[hana::int_c<2>] = 9.9;
  64
  65         BOOST_HANA_RUNTIME_CHECK(xs[hana::int_c<0>] == 9);
  66         BOOST_HANA_RUNTIME_CHECK(xs[hana::int_c<1>] == '9');
  67         BOOST_HANA_RUNTIME_CHECK(xs[hana::int_c<2>] == 9.9);
  68     }
  69
  70     // Make sure we return a rvalue-reference from a temporary map
  71     // (https://github.com/boostorg/hana/issues/90)
  72     {
  73         auto xs = hana::make_map(
  74             hana::make_pair(hana::int_c<0>, 0),
  75             hana::make_pair(hana::int_c<1>, '1'),
  76             hana::make_pair(hana::int_c<2>, 2.2)
  77         );
  78
  79         char&& c = hana::at_key(std::move(xs), hana::int_c<1>);
  80         BOOST_HANA_RUNTIME_CHECK(hana::at_key(xs, hana::int_c<1>) == '1');
  81         c = '9';
  82         BOOST_HANA_RUNTIME_CHECK(hana::at_key(xs, hana::int_c<1>) == '9');
  83     }
  84 }