rapid_json_to_map.h

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/*
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  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.
 
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  permission to link the program and your derivative works with the
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  the program or referenced in the documentation.
 
  This program is distributed in the hope that it will be useful,
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  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
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  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#ifndef ROUTER_SRC_REST_MRS_SRC_HELPER_JSON_RAPID_JSON_TO_MAP_H_
#define ROUTER_SRC_REST_MRS_SRC_HELPER_JSON_RAPID_JSON_TO_MAP_H_
 
#include <list>
#include <string>
 
#include <my_rapidjson_size_t.h>
#include <rapidjson/reader.h>
 
namespace helper {
namespace json {
 
/**
 * This class is a adapter for Reader from RapidJson.
 *
 * This class adapts std::map of strings (keys and values are strings)
 * to be destination of text document conversion done be `rapidjson::Reader`.
 * There are some constrains to what is converted:
 *    * values from top level document are inserted into the map,
 *    * value must be a simple type, sub objects, or arrays are ignored.
 */
class RapidReaderHandlerToMapOfSimpleValues
    : rapidjson::BaseReaderHandler<rapidjson::UTF8<>,
                                   RapidReaderHandlerToMapOfSimpleValues> {
 public:
  using Map = std::map<std::string, std::string>;
  using Result = Map;
  constexpr static rapidjson::ParseFlag k_parse_flags{
      rapidjson::kParseNumbersAsStringsFlag};
 
  RapidReaderHandlerToMapOfSimpleValues(int allowed_levels = 1)
      : allowed_levels_{allowed_levels} {}
 
  const Map &get_result() const { return result_; }
 
 public:  // template overwrites methods from `rapidjson::BaseReaderHandler`
  bool Null() { return String("null", 4, false); }
 
  bool Bool(bool value) {
    if (value) return String("true", 4, false);
 
    return String("false", 5, false);
  }
 
  bool String(const Ch *ch, rapidjson::SizeType size, bool) {
    if (level_ < 1 || level_ > allowed_levels_ || arrays_ > 0) return true;
 
    result_[get_current_key()] = std::string(ch, size);
 
    return static_cast<Override &>(*this).Default();
  }
 
  // Ignoring following methods because, parser should be configured to call
  // "RawNumber" method.
  bool Int(int v) {
    auto r = std::to_string(v);
    return String(r.c_str(), r.length(), false);
  }
 
  bool Uint(unsigned v) {
    auto r = std::to_string(v);
    return String(r.c_str(), r.length(), false);
  }
 
  bool Int64(int64_t v) {
    auto r = std::to_string(v);
    return String(r.c_str(), r.length(), false);
  }
 
  bool Uint64(uint64_t v) {
    auto r = std::to_string(v);
    return String(r.c_str(), r.length(), false);
  }
 
  bool Double(double v) {
    auto r = std::to_string(v);
    return String(r.c_str(), r.length(), false);
  }
 
  /// enabled via kParseNumbersAsStringsFlag, string is not null-terminated (use
  /// length)
  bool RawNumber(const Ch *str, rapidjson::SizeType len, bool copy) {
    return String(str, len, copy);
  }
 
  bool StartObject() {
    if (!key_.name.empty()) {
      keys_.push_back(key_);
    }
    ++level_;
    return true;
  }
 
  bool EndObject(rapidjson::SizeType) {
    --level_;
    if (!keys_.empty()) {
      auto &b = keys_.back();
      if (level_ == b.level) keys_.pop_back();
    }
 
    return true;
  }
 
  bool Key(const Ch *str, rapidjson::SizeType len, bool) {
    key_.name.assign(str, len);
    key_.level = level_;
    return true;
  }
 
  // Ignore arrays
  bool StartArray() {
    ++level_;
    ++arrays_;
    return true;
  }
 
  bool EndArray(rapidjson::SizeType) {
    --level_;
    --arrays_;
    if (!keys_.empty()) {
      auto &b = keys_.back();
      if (level_ == b.level) keys_.pop_back();
    }
    return true;
  }
 
 private:
  std::string get_current_key() const {
    std::string result;
    for (const auto &key : keys_) {
      result += key.name + ".";
    }
    return result + key_.name;
  }
  int allowed_levels_;
  struct KeyValue {
    std::string name;
    int level;
  };
  std::list<KeyValue> keys_;
  KeyValue key_;
  Map result_;
  int level_{0};
  int arrays_{0};
};
 
template <typename SubHandler>
class ExtractSubObjectHandler
    : rapidjson::BaseReaderHandler<rapidjson::UTF8<>,
                                   ExtractSubObjectHandler<SubHandler>> {
  using Base =
      rapidjson::BaseReaderHandler<rapidjson::UTF8<>,
                                   ExtractSubObjectHandler<SubHandler>>;
  using Ch = typename Base::Ch;
 
 public:
  constexpr static rapidjson::ParseFlag k_parse_flags{
      rapidjson::kParseNumbersAsStringsFlag};
 
  using Result = typename SubHandler::Result;
 
  ExtractSubObjectHandler(const std::string &key, SubHandler &sub_handler)
      : key_{key}, sub_handler_{sub_handler} {}
 
  bool Null() {
    if (targer_) return sub_handler_.Null();
 
    return true;
  }
 
  bool Bool(bool value) {
    if (targer_) return sub_handler_.Bool(value);
 
    return true;
  }
 
  bool String(const Ch *ch, rapidjson::SizeType size, bool b) {
    if (targer_) return sub_handler_.String(ch, size, b);
 
    return true;
  }
 
  bool Int(int v) {
    if (targer_) return sub_handler_.Int(v);
 
    return true;
  }
 
  bool Uint(unsigned v) {
    if (targer_) return sub_handler_.Uint(v);
 
    return true;
  }
 
  bool Int64(int64_t v) {
    if (targer_) return sub_handler_.Int64(v);
 
    return true;
  }
 
  bool Uint64(uint64_t v) {
    if (targer_) return sub_handler_.Uint64(v);
 
    return true;
  }
 
  bool Double(double v) {
    if (targer_) return sub_handler_.Double(v);
 
    return true;
  }
 
  /// enabled via kParseNumbersAsStringsFlag, string is not null-terminated (use
  /// length)
  bool RawNumber(const Ch *str, rapidjson::SizeType len, bool copy) {
    if (targer_) return sub_handler_.RawNumber(str, len, copy);
 
    return true;
  }
 
  bool StartObject() {
    if (targer_) sub_handler_.StartObject();
    ++level_;
    return true;
  }
 
  bool EndObject(rapidjson::SizeType size) {
    if (targer_) sub_handler_.EndObject(size);
    --level_;
    return true;
  }
 
  bool Key(const Ch *str, rapidjson::SizeType len, bool b) {
    if (targer_) sub_handler_.Key(str, len, b);
    if (level_ != 1) return true;
    targer_ = key_ == std::string(str, len);
    return true;
  }
 
  // Ignore arrays
  bool StartArray() {
    if (targer_) sub_handler_.StartArray();
    ++level_;
    return true;
  }
 
  bool EndArray(rapidjson::SizeType size) {
    if (targer_) sub_handler_.EndArray(size);
    --level_;
    return true;
  }
 
  Result get_result() { return sub_handler_.get_result(); }
 
 private:
  std::string key_;
  SubHandler &sub_handler_;
  int level_{0};
  bool targer_{false};
};
 
}  // namespace json
}  // namespace helper
 
#endif  // ROUTER_SRC_REST_MRS_SRC_HELPER_JSON_RAPID_JSON_TO_MAP_H_