ceph/src/boost/libs/hana/example/struct.mcd.nested.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/concept/struct.hpp>
   7 #include <boost/hana/config.hpp>
   8 #include <boost/hana/equal.hpp>
   9 #include <boost/hana/find.hpp>
  10 #include <boost/hana/functional/id.hpp>
  11 #include <boost/hana/integral_constant.hpp>
  12 #include <boost/hana/not_equal.hpp>
  13 #include <boost/hana/pair.hpp>
  14 #include <boost/hana/string.hpp>
  15 #include <boost/hana/tuple.hpp>
  16
  17 #include <string>
  18 #include <utility>
  19 namespace hana = boost::hana;
  20
  21
  22 //! [main]
  23 struct Person {
  24     std::string name;
  25     int age;
  26
  27     struct hana_accessors_impl {
  28         static BOOST_HANA_CONSTEXPR_LAMBDA auto apply() {
  29             return boost::hana::make_tuple(
  30                 boost::hana::make_pair(BOOST_HANA_STRING("name"),
  31                 [](auto&& p) -> decltype(auto) {
  32                     return boost::hana::id(std::forward<decltype(p)>(p).name);
  33                 }),
  34                 boost::hana::make_pair(BOOST_HANA_STRING("age"),
  35                 [](auto&& p) -> decltype(auto) {
  36                     return boost::hana::id(std::forward<decltype(p)>(p).age);
  37                 })
  38             );
  39         }
  40     };
  41 };
  42 //! [main]
  43
  44 int main() {
  45     Person john{"John", 30}, bob{"Bob", 40};
  46     BOOST_HANA_RUNTIME_CHECK(hana::equal(john, john));
  47     BOOST_HANA_RUNTIME_CHECK(hana::not_equal(john, bob));
  48
  49     BOOST_HANA_RUNTIME_CHECK(hana::find(john, BOOST_HANA_STRING("name")) == hana::just("John"));
  50     BOOST_HANA_RUNTIME_CHECK(hana::find(john, BOOST_HANA_STRING("age")) == hana::just(30));
  51     BOOST_HANA_CONSTANT_CHECK(hana::find(john, BOOST_HANA_STRING("foo")) == hana::nothing);
  52
  53     BOOST_HANA_RUNTIME_CHECK(hana::to_tuple(john) == hana::make_tuple(
  54         hana::make_pair(BOOST_HANA_STRING("name"), "John"),
  55         hana::make_pair(BOOST_HANA_STRING("age"), 30)
  56     ));
  57 }