cpp-json/include/json/binder/json_object_binder.hpp

//
//  json_object_binder.hpp
//  json
//
//  Created by Sam Jaffe on 4/23/16.
//

#pragma once

#include "json_binder.hpp"
#include "json_binder_discard.hpp"
#include "json_direct_binder.hpp"

#include <map>
#include <set>
#include <string>

namespace json { namespace binder {
  template <typename T> class object_binder : public binder_impl<T> {
  public:
    object_binder() {}
    virtual binder_impl<T> * clone() const override {
      return new object_binder(*this);
    }

    template <typename V>
    object_binder & operator()(std::string const & k, V T::*ptr,
                               binder_impl<V> const & v) {
      return (*this)(k, binder<T>(new forward_binder<T, V>(ptr, binder<V>(v))));
    }

    object_binder & operator()(std::string const & k, binder<T> const & v) {
      mapping.emplace(k, v);
      return *this;
    }

    virtual void parse(T & object, char const *& data,
                       parser::options opts) const override {
      const char ch = json::helper::get_next_element(data);
      if (ch == '{') {
        parse_object(object, ++data, opts);
      } else {
        throw not_an_object_exception(object);
      }
    }

    virtual void write(T const & val, std::ostream & data) const override {
      data << '{';
      auto it = mapping.begin(), end = mapping.end();
      if (it != end) {
        data << '"' << it->first << '"' << ':';
        it->second.write(val, data);
        for (++it; it != end; ++it) {
          data << ',';
          data << '"' << it->first << '"' << ':';
          it->second.write(val, data);
        }
      }
      data << '}';
    }

    void parse_object(T & object, char const *& data,
                      parser::options opts) const {
      std::string key;
      std::set<std::string> unparsed_keys;
      for (auto & p : mapping) {
        unparsed_keys.insert(p.first);
      }
      while (*data && *data != '}') {
        if (json::helper::get_next_element(data) != '"') {
          throw malformed_object_key(*data);
        }
        json::helper::parse_string(key, data);
        if (json::helper::get_next_element(data) != ':') {
          throw malformed_object_association(*data);
        }
        auto it = mapping.find(key);
        if (it != mapping.end()) {
          unparsed_keys.erase(key);
          it->second.parse(object, ++data, opts);
        } else if (opts & parser::disable_unknown_keys) {
          throw json::malformed_json_exception("Unexpected key " + key);
        } else {
          parse_discard_token(++data);
        }
        json::helper::advance_to_boundary('}', data);
      }
      if (*data) {
        ++data;
      } else {
        throw unterminated_json_object();
      }
      if (!unparsed_keys.empty() && opts & parser::disable_missing_keys) {
        throw json::malformed_json_exception{
            "missing certain keys from object construction TODO"};
      }
    }

    template <typename E>
    object_binder & operator()(std::string const & s, E T::*p) {
      return operator()(s, binder<T>(new direct_binder<T, E>(p)));
    }

  private:
    std::map<std::string, binder<T>> mapping;
  };
}}