ceph/src/boost/libs/pfr/test/run/for_each_field.cpp

   1 // Copyright (c) 2016-2022 Antony Polukhin
   2 //
   3 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   4 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #include <boost/pfr/core.hpp>
   7 #include <boost/core/lightweight_test.hpp>
   8 #include <sstream>
   9
  10 // Test case was inspired by Bruno Dutra. Thanks!
  11
  12 enum class color {
  13     red,
  14     green,
  15     blue
  16 };
  17
  18 std::ostream& operator <<(std::ostream& os, color c) {
  19     switch(c) {
  20         case color::red:
  21             os << "red";
  22             break;
  23         case color::green:
  24             os << "green";
  25             break;
  26         case color::blue:
  27             os << "blue";
  28             break;
  29     };
  30
  31     return os;
  32 }
  33
  34
  35 struct my_constexpr {
  36     constexpr my_constexpr() {}
  37 };
  38
  39 std::ostream& operator <<(std::ostream& os, my_constexpr) {
  40     return os << "{}";
  41 }
  42
  43 struct reg {
  44     const int a;
  45     char b;
  46     const my_constexpr d;
  47     const color f;
  48     const char* g;
  49 };
  50
  51 struct simple {
  52     int a;
  53     char b;
  54     short d;
  55 };
  56
  57 struct empty{};
  58
  59
  60 int main () {
  61     std::size_t control = 0;
  62
  63     int v = {};
  64     boost::pfr::for_each_field(v, [&control](auto&& val, std::size_t i) {
  65         BOOST_TEST_EQ(i, control);
  66         (void)val;
  67         ++ control;
  68     });
  69     BOOST_TEST_EQ(control, 1);
  70
  71     control = 0;
  72     int array[10] = {};
  73     boost::pfr::for_each_field(array, [&control](auto&& val, std::size_t i) {
  74         BOOST_TEST_EQ(i, control);
  75         (void)val;
  76         ++ control;
  77     });
  78     BOOST_TEST_EQ(control, 10);
  79
  80     std::stringstream ss;
  81     boost::pfr::for_each_field(reg{42, 'a', {}, color::green, "hello world!"}, [&ss](auto&& val, std::size_t i) {
  82         if (i) {
  83             ss << ", ";
  84         }
  85         ss << val;
  86     });
  87     BOOST_TEST_EQ(std::string("42, a, {}, green, hello world!"), ss.str());
  88     ss.str("");
  89
  90     control = 0;
  91     boost::pfr::for_each_field(reg{42, 'a', {}, color::green, "hello world!"}, [&ss, &control](auto&& val, auto i) {
  92         if (!!decltype(i)::value) {
  93             ss << ", ";
  94         }
  95         BOOST_TEST_EQ(decltype(i)::value, control);
  96         ++ control;
  97         ss << val;
  98     });
  99     BOOST_TEST_EQ(std::string("42, a, {}, green, hello world!"), ss.str());
 100     ss.str("");
 101
 102     boost::pfr::for_each_field(reg{42, 'a', {}, color::green, "hello world!"}, [&ss](auto&& val) {
 103         ss << val << ' ';
 104     });
 105     BOOST_TEST_EQ(std::string("42 a {} green hello world! "), ss.str());
 106     ss.str("");
 107
 108     std::cout << '\n';
 109     boost::pfr::for_each_field(simple{42, 'a', 3},  [&ss](auto&& val) {
 110         ss << val << ' ';
 111     });
 112     BOOST_TEST_EQ("42 a 3 ", ss.str());
 113     ss.str("");
 114
 115     boost::pfr::for_each_field(empty{},  [&ss](auto&& val) {
 116         ss << val << ' ';
 117     });
 118     BOOST_TEST_EQ("", ss.str());
 119     ss.str("");
 120
 121     return boost::report_errors();
 122 }