FsiJsonUtils.h

Go to the documentation of this file.

/*
 * Copyright 2020 OmniSci, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <rapidjson/document.h>
#include <map>
#include <vector>
#include "Logger/Logger.h"
namespace foreign_storage {

// helper functions for serializing/deserializing objects to rapidjson value
namespace json_utils {

// Forward declare for vector/map functions
template <class T>
void add_value_to_object(rapidjson::Value& object,
                         const T& value,
                         const std::string& name,
                         rapidjson::Document::AllocatorType& allocator);
template <class T>
void get_value_from_object(const rapidjson::Value& object,
                           T& value,
                           const std::string& name);

// Basic types (more can be added as required) will be defined in source file
// int
void set_value(rapidjson::Value& json_val,
               const long unsigned int& value,
               rapidjson::Document::AllocatorType& allocator);
void get_value(const rapidjson::Value& json_val, long unsigned int& value);
// unsigned long int / size_t
void set_value(rapidjson::Value& json_val,
               const int& value,
               rapidjson::Document::AllocatorType& allocator);
void get_value(const rapidjson::Value& json_val, int& value);
// string
void set_value(rapidjson::Value& json_val,
               const std::string& value,
               rapidjson::Document::AllocatorType& allocator);
void get_value(const rapidjson::Value& json_val, std::string& value);

// std::vector
template <class T>
void set_value(rapidjson::Value& json_val,
               const std::vector<T>& vector_value,
               rapidjson::Document::AllocatorType& allocator) {
  json_val.SetArray();
  for (const auto& value : vector_value) {
    rapidjson::Value json_obj;
    set_value(json_obj, value, allocator);
    json_val.PushBack(json_obj, allocator);
  }
}

template <class T>
void get_value(const rapidjson::Value& json_val, std::vector<T>& vector_value) {
  CHECK(json_val.IsArray());
  CHECK(vector_value.size() == 0);
  for (const auto& json_obj : json_val.GetArray()) {
    T val;
    get_value(json_obj, val);
    vector_value.push_back(val);
  }
}

// std::map
template <class T, class V>
void set_value(rapidjson::Value& json_val,
               const std::map<T, V>& map_value,
               rapidjson::Document::AllocatorType& allocator) {
  json_val.SetArray();
  for (const auto& pair : map_value) {
    rapidjson::Value pair_obj;
    pair_obj.SetObject();
    add_value_to_object(pair_obj, pair.first, "key", allocator);
    add_value_to_object(pair_obj, pair.second, "value", allocator);
    json_val.PushBack(pair_obj, allocator);
  }
}

template <class T, class V>
void get_value(const rapidjson::Value& json_val, std::map<T, V>& map_value) {
  CHECK(json_val.IsArray());
  CHECK(map_value.size() == 0);
  for (const auto& json_obj : json_val.GetArray()) {
    CHECK(json_obj.IsObject());
    T key;
    V value;
    get_value_from_object(json_obj, key, "key");
    get_value_from_object(json_obj, value, "value");
    map_value[key] = value;
  }
}

// Serialize value into json object with valid set_value functions
template <class T>
void add_value_to_object(rapidjson::Value& object,
                         const T& value,
                         const std::string& name,
                         rapidjson::Document::AllocatorType& allocator) {
  CHECK(object.IsObject());
  CHECK(!object.HasMember(name));
  rapidjson::Value json_val;
  set_value(json_val, value, allocator);
  rapidjson::Value json_name;
  json_name.SetString(name, allocator);
  object.AddMember(json_name, json_val, allocator);
}

// Deserialize value from json object with valid get_value/set_value functions
template <class T>
void get_value_from_object(const rapidjson::Value& object,
                           T& value,
                           const std::string& name) {
  CHECK(object.IsObject());
  CHECK(object.HasMember(name));
  get_value(object[name], value);
}

// Read JSON content from the given file path
rapidjson::Document read_from_file(const std::string& file_path);

// Write JSON content (encapsulated by the given Document object) to the given file path
void write_to_file(const rapidjson::Document& document, const std::string& file_path);

}  // namespace json_utils
}  // namespace foreign_storage