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

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

#pragma once

namespace json { namespace binder {
  template <typename T, typename V, typename C>
  class associative_binder : public binder_impl<T> {
  public:
    associative_binder(C T::*p) : ptr(p), impl(value_binder<V>()) {}
    associative_binder(C T::*p, binder<V> const & i) : ptr(p), impl(i) {}
    virtual binder_impl<T>* clone() const override { return new associative_binder(*this); }
    
    virtual void parse(T& val, char const*& data, parser::options opts) const override {
      const char ch = json::helper::get_next_element(data);
      if (ch != '{') {
        throw json::malformed_json_exception("Expected an object type");
      }
      ++data;
      
      V to_make;
      C & map = val.*ptr;
      std::string key;
      while (*data && *data != '}') {
        json::helper::parse_string(key, data);
        if (json::helper::get_next_element(data) != ':') {
          throw json::malformed_json_exception(std::string("Expected key:value pair delimited by ':', got '") + *data + "' instead");
        }
        impl.parse(to_make, ++data, opts);
        map.emplace(key, std::move(to_make));
        json::helper::advance_to_boundary('}', data);
      }
      if (*data) ++data;
      else throw json::unterminated_json_exception("Reached end of parse string without finding object end");
    }
    
    virtual void write(T const& val, std::ostream & data) const override {
      data << '{';
      std::map<std::string, V> const & map = val.*ptr;
      typename std::map<std::string, V>::const_iterator it = map.begin(), end = map.end();
      if (it != end) {
        data << '"' << it->first << '"' << ':';
        impl.write(it->second, data);
        for (++it; it != end; ++it) {
          data << ',';
          data << '"' << it->first << '"' << ':';
          impl.write(it->second, data);
        }
      }
      data << '}';
    }
  private:
    std::map<std::string, V> T::*ptr;
    binder<V> impl;
  };
  
#define ASSOCIATIVE_DIRECT_BINDER( C ) \
  template <typename T, typename V, typename... O> \
  class direct_binder<T, C<std::string, V, O...> > : \
  public associative_binder<T, V, C<std::string, V, O...>> { \
  public: \
    using associative_binder<T, V, C<std::string, V, O...>>::associative_binder; \
  }

  ASSOCIATIVE_DIRECT_BINDER( std::map );
//  ASSOCIATIVE_DIRECT_BINDER( std::unordered_map );
} }