cpp-json/json_common.h

//
//  json_common.h
//  json
//
//  Created by Sam Jaffe on 4/22/16.
//

#pragma once

#include <cstdlib>
#include <stdexcept>
#include <string>

namespace json {
  class malformed_json_exception : public std::domain_error {
    using std::domain_error::domain_error;
  };
}

namespace json {
  namespace helper {
    const char get_next_element(char const*& data) {
      while (isspace(*data)) ++data;
      return *data;
    }
    
    template <char const E>
    void advance_to_boundary(char const*& data) {
      switch (get_next_element(data)) {
        case ',': // This is there 'more data remains' token for the compound value
          ++data;
          break;
        case E: // This is the end-token for the compound value
          break;
        default: // Error, malformed JSON
          throw json::malformed_json_exception(std::string("Expected to recieve container delimiter ',' or '") + E + "', got '" + *data + "' instead");
          break;
      }
    }
    
    template <typename T>
    void parse_string(T& json, char const*& data) {
      char const* start = data;
      while (*++data) {
        if (*data == '"' && *(data-1) != '\\') {
          json = std::string(start+1, data);
          ++data;
          return;
        }
      }
      throw json::malformed_json_exception("Could not locate end of string");
    }
    
    template <typename T>
    void parse_numeric(T& json, char const*& data) {
      // TODO: more sophisticated float detection?
      char const* start = data;
      while (*++data) {
        if (*data == '.') {
          while (isnumber(*++data));
          json = atof(start);
          break;
        } else if (!isnumber(*data)) {
          json = atoi(start);
          break;
        }
      }
    }
    
  }
}