text_to.h

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/*
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*/
 
#ifndef ROUTER_SRC_REST_MRS_SRC_HELPER_JSON_TEXT_TO_H_
#define ROUTER_SRC_REST_MRS_SRC_HELPER_JSON_TEXT_TO_H_
 
#include <type_traits>
 
#include <my_rapidjson_size_t.h>
#include <rapidjson/document.h>
#include <rapidjson/memorystream.h>
#include <rapidjson/reader.h>
 
namespace helper {
namespace json {
 
/**
 * Convert text representation of json object/value to type defined by
 * 'Handler'.
 *
 * The 'Handler' must be a child class of `rapidjson::BaseReaderHandler`. The
 * child class must contain type/alias definition of returned result, under
 * "Result" alias and `get_result` method. For example:
 *
 *     class HandlerSomeExample
 *          : rapidjson::BaseReaderHandler<rapidjson::UTF8<>,HandlerSomeExample>
 * { public: using Result = std::string;
 *
 *         ...
 *      };
 */
template <typename Handler, typename Container>
bool text_to(Handler *handler, const Container &c) {
  static_assert(
      std::is_same<typename Container::value_type, char>::value ||
      std::is_same<typename Container::value_type, unsigned char>::value);
  if (c.size() == 0) {
    return false;
  }
  rapidjson::MemoryStream memory_stream{
      reinterpret_cast<const char *>(&*c.begin()), c.size()};
  rapidjson::Reader read;
 
  return !read.Parse<Handler::k_parse_flags>(memory_stream, *handler).IsError();
}
 
template <typename Container>
bool text_to(rapidjson::Document *doc, const Container &c) {
  static_assert(
      std::is_same<typename Container::value_type, char>::value ||
      std::is_same<typename Container::value_type, unsigned char>::value);
  if (c.size() == 0) {
    return false;
  }
  doc->Parse(reinterpret_cast<const char *>(&*c.begin()), c.size());
  return !doc->HasParseError();
}
 
inline bool text_to(rapidjson::Document *doc, const std::string &str) {
  doc->Parse(str.c_str());
  return !doc->HasParseError();
}
 
inline bool text_to(rapidjson::Document *doc, const char *str) {
  doc->Parse(str);
  return !doc->HasParseError();
}
 
inline bool text_to(rapidjson::Document::Object *obj, const std::string &str) {
  rapidjson::Document doc;
 
  if (!text_to(&doc, str)) return false;
  if (!doc.IsObject()) return false;
 
  *obj = doc.GetObject();
 
  return true;
}
 
inline bool text_to(rapidjson::Value *val, const std::string &str) {
  rapidjson::Document doc;
 
  if (!text_to(&doc, str)) return false;
  if (!doc.IsObject()) return false;
 
  *val = doc.GetObject();
 
  return true;
}
 
/**
 * Convert text representation of json object/value to type defined by
 * 'Handler'.
 *
 * The 'Handler' must be a child class of `rapidjson::BaseReaderHandler`. The
 * child class must contain type/alias definition of returned result, under
 * "Result" alias and `get_result` method. For example:
 *
 *     class HandlerSomeExample
 *          : rapidjson::BaseReaderHandler<rapidjson::UTF8<>,HandlerSomeExample>
 * { public: using Result = std::string;
 *
 *         ...
 *      };
 */
template <typename Handler, typename Container, typename... HandlerArgs>
typename Handler::Result text_to_handler(const Container &c,
                                         HandlerArgs &&...args) {
  Handler handler(std::forward<HandlerArgs>(args)...);
 
  text_to<Handler, Container>(&handler, c);
 
  return handler.get_result();
}
 
inline rapidjson::Document text_to_document(const std::string &str) {
  rapidjson::Document result;
  text_to(&result, str);
  return result;
}
 
}  // namespace json
}  // namespace helper
 
#endif  // ROUTER_SRC_REST_MRS_SRC_HELPER_JSON_TEXT_TO_H_