ceph/src/boost/libs/pfr/example/get.cpp

   1 // Copyright 2016-2020 Antony Polukhin
   2
   3 // Distributed under the Boost Software License, Version 1.0.
   4 // (See the accompanying file LICENSE_1_0.txt
   5 // or a copy at <http://www.boost.org/LICENSE_1_0.txt>.)
   6
   7 //[pfr_example_get
   8 /*`
   9     The following example shows how to access structure fields by index using [funcref boost::pfr::get].
  10
  11     Let's define some structure:
  12 */
  13 #include <boost/pfr/core.hpp>
  14
  15 struct foo {            // defining structure
  16     int some_integer;
  17     char c;
  18 };
  19
  20 /*`
  21     We can access fields of that structure by index:
  22 */
  23 foo f {777, '!'};
  24 auto& r1 = boost::pfr::get<0>(f); // accessing field with index 0, returns reference to `foo::some_integer`
  25 auto& r2 = boost::pfr::get<1>(f); // accessing field with index 1, returns reference to `foo::c`
  26 //] [/pfr_example_get]
  27
  28
  29 int main() {
  30     if (r1 != 777) return 1;
  31     if (r2 != '!') return 2;
  32
  33     r1 = 42;
  34     r2 = 'A';
  35
  36     if (r1 != 42) return 3;
  37     if (r2 != 'A') return 4;
  38     if (f.some_integer != 42) return 5;
  39     if (f.c != 'A') return 6;
  40
  41     return 0;
  42 }