ceph/src/boost/libs/hana/example/accessors.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/accessors.hpp>
   6 #include <boost/hana/assert.hpp>
   7 #include <boost/hana/at.hpp>
   8 #include <boost/hana/define_struct.hpp>
   9 #include <boost/hana/equal.hpp>
  10 #include <boost/hana/first.hpp>
  11 #include <boost/hana/integral_constant.hpp>
  12 #include <boost/hana/second.hpp>
  13 #include <boost/hana/string.hpp>
  14
  15 #include <string>
  16 namespace hana = boost::hana;
  17
  18
  19 struct Person {
  20     BOOST_HANA_DEFINE_STRUCT(Person,
  21         (std::string, name),
  22         (unsigned short, age)
  23     );
  24 };
  25
  26 int main() {
  27     constexpr auto accessors = hana::accessors<Person>();
  28     BOOST_HANA_CONSTANT_CHECK(
  29         hana::first(accessors[hana::size_c<0>]) == BOOST_HANA_STRING("name")
  30     );
  31
  32     BOOST_HANA_CONSTANT_CHECK(
  33         hana::first(accessors[hana::size_c<1>]) == BOOST_HANA_STRING("age")
  34     );
  35
  36     constexpr auto get_name = hana::second(accessors[hana::size_c<0>]);
  37     constexpr auto get_age = hana::second(accessors[hana::size_c<1>]);
  38
  39     Person john{"John", 30};
  40     BOOST_HANA_RUNTIME_CHECK(get_name(john) == "John");
  41     BOOST_HANA_RUNTIME_CHECK(get_age(john) == 30);
  42 }