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3rdparty/boost_1_81_0/libs/hana/example/struct.mcd.nested.cpp 1.91 KB
73ef4ff3   Hu Chunming   提交三方库
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  // Copyright Louis Dionne 2013-2022
  // Distributed under the Boost Software License, Version 1.0.
  // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
  
  #include <boost/hana/assert.hpp>
  #include <boost/hana/concept/struct.hpp>
  #include <boost/hana/config.hpp>
  #include <boost/hana/equal.hpp>
  #include <boost/hana/find.hpp>
  #include <boost/hana/functional/id.hpp>
  #include <boost/hana/integral_constant.hpp>
  #include <boost/hana/not_equal.hpp>
  #include <boost/hana/pair.hpp>
  #include <boost/hana/string.hpp>
  #include <boost/hana/tuple.hpp>
  
  #include <string>
  #include <utility>
  namespace hana = boost::hana;
  
  
  //! [main]
  struct Person {
      std::string name;
      int age;
  
      struct hana_accessors_impl {
          static BOOST_HANA_CONSTEXPR_LAMBDA auto apply() {
              return boost::hana::make_tuple(
                  boost::hana::make_pair(BOOST_HANA_STRING("name"),
                  [](auto&& p) -> decltype(auto) {
                      return boost::hana::id(std::forward<decltype(p)>(p).name);
                  }),
                  boost::hana::make_pair(BOOST_HANA_STRING("age"),
                  [](auto&& p) -> decltype(auto) {
                      return boost::hana::id(std::forward<decltype(p)>(p).age);
                  })
              );
          }
      };
  };
  //! [main]
  
  int main() {
      Person john{"John", 30}, bob{"Bob", 40};
      BOOST_HANA_RUNTIME_CHECK(hana::equal(john, john));
      BOOST_HANA_RUNTIME_CHECK(hana::not_equal(john, bob));
  
      BOOST_HANA_RUNTIME_CHECK(hana::find(john, BOOST_HANA_STRING("name")) == hana::just("John"));
      BOOST_HANA_RUNTIME_CHECK(hana::find(john, BOOST_HANA_STRING("age")) == hana::just(30));
      BOOST_HANA_CONSTANT_CHECK(hana::find(john, BOOST_HANA_STRING("foo")) == hana::nothing);
  
      BOOST_HANA_RUNTIME_CHECK(hana::to_tuple(john) == hana::make_tuple(
          hana::make_pair(BOOST_HANA_STRING("name"), "John"),
          hana::make_pair(BOOST_HANA_STRING("age"), 30)
      ));
  }