1// Copyright Louis Dionne 2013-2022
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/config.hpp>
7#include <boost/hana/core/to.hpp>
8#include <boost/hana/equal.hpp>
9#include <boost/hana/find.hpp>
10#include <boost/hana/functional/id.hpp>
11#include <boost/hana/fwd/accessors.hpp>
12#include <boost/hana/integral_constant.hpp>
13#include <boost/hana/not_equal.hpp>
14#include <boost/hana/pair.hpp>
15#include <boost/hana/string.hpp>
16#include <boost/hana/tuple.hpp>
17
18#include <string>
19#include <utility>
20namespace hana = boost::hana;
21
22
23//! [main]
24struct Person {
25 Person(std::string const& name, int age) : name_(name), age_(age) { }
26
27 std::string const& get_name() const { return name_; }
28 int get_age() const { return age_; }
29
30private:
31 std::string name_;
32 int age_;
33};
34
35namespace boost { namespace hana {
36 template <>
37 struct accessors_impl<Person> {
38 static BOOST_HANA_CONSTEXPR_LAMBDA auto apply() {
39 return make_tuple(
40 make_pair(BOOST_HANA_STRING("name"), [](auto&& p) -> std::string const& {
41 return p.get_name();
42 }),
43 make_pair(BOOST_HANA_STRING("age"), [](auto&& p) {
44 return p.get_age();
45 })
46 );
47 }
48 };
49}}
50//! [main]
51
52int main() {
53 auto name = BOOST_HANA_STRING("name");
54 auto age = BOOST_HANA_STRING("age");
55
56 Person john{"John", 30}, bob{"Bob", 40};
57 BOOST_HANA_RUNTIME_CHECK(hana::equal(john, john));
58 BOOST_HANA_RUNTIME_CHECK(hana::not_equal(john, bob));
59
60 BOOST_HANA_RUNTIME_CHECK(hana::find(john, name) == hana::just("John"));
61 BOOST_HANA_RUNTIME_CHECK(hana::find(john, age) == hana::just(30));
62 BOOST_HANA_CONSTANT_CHECK(hana::find(john, BOOST_HANA_STRING("foo")) == hana::nothing);
63
64 BOOST_HANA_RUNTIME_CHECK(hana::to_tuple(john) == hana::make_tuple(
65 hana::make_pair(name, "John"),
66 hana::make_pair(age, 30)
67 ));
68}
69

source code of boost/libs/hana/example/struct.custom_accessor.cpp