test_boost_ptree.cpp

#include <boost/foreach.hpp>
#include <boost/property_tree/json_parser.hpp>
#include <boost/property_tree/ptree.hpp>
#include <iostream>
#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;
  }
};

void read_file(const string &filename, stringstream &buffer) {
  ifstream file{filename};
  if (file.good()) {
    buffer << file.rdbuf();
  }
}

coordinate_t calc(stringstream &text) {
  boost::property_tree::ptree jobj;
  boost::property_tree::read_json(text, jobj);
  auto x = 0.0, y = 0.0, z = 0.0;
  auto len = 0;

  BOOST_FOREACH (boost::property_tree::ptree::value_type &coord,
                 jobj.get_child("coordinates")) {
    len += 1;
    x += coord.second.get<double>("x");
    y += coord.second.get<double>("y");
    z += coord.second.get<double>("z");
  }

  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 json = stringstream(v);
    auto left = calc(json);
    if (left != right) {
      cerr << left << " != " << right << endl;
      exit(EXIT_FAILURE);
    }
  }

  stringstream text;
  read_file("/tmp/1.json", text);

  const auto &results = notifying_invoke(
      [&]() { return calc(text); }, "C++/{} (Boost.PropertyTree)", COMPILER);

  cout << results << endl;
}