test_simdjson_dom.cpp

#include <iostream>
#include <libnotify.h>

#include "simdjson.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;
  }
};

using namespace simdjson;
using namespace simdjson::builtin;

coordinate_t calc(const padded_string &text) {
  dom::parser pj;
  // allocate memory for parsing up to p.size() bytes
  auto allocate_error = pj.allocate(text.size());
  if (allocate_error) {
    cerr << allocate_error << endl;
    exit(EXIT_FAILURE);
  }

  dom::object doc;
  const auto &error = pj.parse(text).get(doc);
  if (error) {
    cerr << error << endl;
    exit(EXIT_FAILURE);
  }

  auto x = 0.0, y = 0.0, z = 0.0;
  auto len = 0;

  for (auto coord : doc["coordinates"]) {
    double x_coord = coord["x"];
    x += x_coord;

    double y_coord = coord["y"];
    y += y_coord;

    double z_coord = coord["z"];
    z += z_coord;
    len++;
  }
  return coordinate_t{x / len, y / len, z / len};
}

int main() {
  auto right = coordinate_t{2.0, 0.5, 0.25};
  // The _padded suffix creates a simdjson::padded_string instance
  for (const padded_string &v :
       {R"({"coordinates":[{"x":2.0,"y":0.5,"z":0.25}]})"_padded,
        R"({"coordinates":[{"y":0.5,"x":2.0,"z":0.25}]})"_padded}) {
    auto left = calc(v);
    if (left != right) {
      cerr << left << " != " << right << endl;
      exit(EXIT_FAILURE);
    }
  }

  padded_string text;
  const auto &error = padded_string::load("/tmp/1.json").get(text);
  if (error) {
    cerr << "could not load file" << endl;
    return EXIT_FAILURE;
  }

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

  cout << results << endl;
}