ceph/src/jaegertracing/opentelemetry-cpp/third_party/nlohmann-json/doc/examples/parse__string__parser_callback_t.cpp

   1 #include <iostream>
   2 #include <iomanip>
   3 #include <nlohmann/json.hpp>
   4
   5 using json = nlohmann::json;
   6
   7 int main()
   8 {
   9     // a JSON text
  10     auto text = R"(
  11     {
  12         "Image": {
  13             "Width":  800,
  14             "Height": 600,
  15             "Title":  "View from 15th Floor",
  16             "Thumbnail": {
  17                 "Url":    "http://www.example.com/image/481989943",
  18                 "Height": 125,
  19                 "Width":  100
  20             },
  21             "Animated" : false,
  22             "IDs": [116, 943, 234, 38793]
  23         }
  24     }
  25     )";
  26
  27     // parse and serialize JSON
  28     json j_complete = json::parse(text);
  29     std::cout << std::setw(4) << j_complete << "\n\n";
  30
  31
  32     // define parser callback
  33     json::parser_callback_t cb = [](int depth, json::parse_event_t event, json & parsed)
  34     {
  35         // skip object elements with key "Thumbnail"
  36         if (event == json::parse_event_t::key and parsed == json("Thumbnail"))
  37         {
  38             return false;
  39         }
  40         else
  41         {
  42             return true;
  43         }
  44     };
  45
  46     // parse (with callback) and serialize JSON
  47     json j_filtered = json::parse(text, cb);
  48     std::cout << std::setw(4) << j_filtered << '\n';
  49 }