test_libjson.cpp

#include <fstream>
#include <iostream>
#include <json-c/json.h>
#include <libnotify.h>

#ifdef __clang__
static constexpr auto COMPILER = "clang++";
#else
static constexpr auto COMPILER = "g++";
#endif

using namespace std;

struct coordinate_t {
  double x;
  double y;
  double z;

  auto operator<=>(const coordinate_t &) const = default;

  friend ostream &operator<<(ostream &out, const coordinate_t &point) {
    out << "coordinate_t {x: " << point.x << ", y: " << point.y
        << ", z: " << point.z << "}";
    return out;
  }
};

string read_file(const string &filename) {
  ifstream file{filename};
  if (!file.good()) {
    return {};
  }
  return string{istreambuf_iterator<char>{file}, {}};
}

coordinate_t calc(const string &text) {
  auto jobj = json_tokener_parse(text.c_str());

  json_object *coordinates;
  if (!json_object_object_get_ex(jobj, "coordinates", &coordinates)) {
    exit(EXIT_FAILURE);
  }

  auto len = json_object_array_length(coordinates);
  auto x = 0.0, y = 0.0, z = 0.0;

  for (size_t i = 0; i < len; i++) {
    auto coord = json_object_array_get_idx(coordinates, i);
    json_object *xobj, *yobj, *zobj;
    if (json_object_object_get_ex(coord, "x", &xobj) &&
        json_object_object_get_ex(coord, "y", &yobj) &&
        json_object_object_get_ex(coord, "z", &zobj)) {
      x += json_object_get_double(xobj);
      y += json_object_get_double(yobj);
      z += json_object_get_double(zobj);
    }
  }

  return coordinate_t{x / len, y / len, z / len};
}

int main() {
  auto right = coordinate_t{2.0, 0.5, 0.25};
  for (auto v : {R"({"coordinates":[{"x":2.0,"y":0.5,"z":0.25}]})",
                 R"({"coordinates":[{"y":0.5,"x":2.0,"z":0.25}]})"}) {
    auto left = calc(v);
    if (left != right) {
      cerr << left << " != " << right << endl;
      exit(EXIT_FAILURE);
    }
  }

  const auto &text = read_file("/tmp/1.json");

  const auto &results = notifying_invoke([&]() { return calc(text); },
                                         "C++/{} (json-c)", COMPILER);

  cout << results << endl;
}