cpp-json/json_common.cpp

//
//  json_binder.cpp
//  json
//
//  Created by Sam Jaffe on 4/23/16.
//

#include "json_common.hpp"

namespace json {
  namespace helper {
    namespace {
      std::string get_no_end_error(char expected, char found) {
        char str[64] = { '\0' };
        snprintf(str, sizeof(str),
                 "Expected delimeter: ',' or '%c', got '%c' instead",
                 expected, found);
        return str;
      }
    }
    
    numeric_token_info::numeric_token_info(char const * start)
    : val(0)
    , it(start)
    , end(start)
    , is_double(false)
    , is_negative(*start == '-') {
      if ( is_negative ) { ++it; ++end; }
      for (char c = *end;
           strchr(",]}", c) == NULL && !isspace(c);
           c = *++end) {
        is_double |= !isdigit(*end);
      }
      
      if (end == it) {
        throw unterminated_json_exception("Expected any token, got nothing");
      }
    }
    
    numeric_state numeric_token_info::parse_numeric() {
      static uint_jt const threshold = (UINT_JT_MAX / 10);
      val = 0;
      for (char c = *it; it != end; c = *++it) {
        int_jt digit = static_cast<int_jt>(c - '0');
        if (val > threshold ||
            ( val == threshold && ((it + 1) < end ||
              digit > INT_JT_MAX_LAST_DIGIT))) {
          return DOUBLE;
        }
        val = (10 * val) + digit;
      }
      return INTEGER;
    }


    const char get_next_element(char const*& data) {
      while (isspace(*data)) ++data;
      return *data;
    }
    
    void advance_to_boundary(char const endtok, char const*& data) {
      char const next = get_next_element(data);
      if (next == ',') {
        ++data;
      } else if (next != endtok) {
        throw json::unterminated_json_exception(get_no_end_error(endtok, *data));
      }
    }
    
    int reverse_count(char const * data, char val) {
      int i = 0;
      while (*data-- == val) { ++i; }
      return i;
    }
    
    std::string replace_all(std::string && str, std::string const & from, std::string const & to) {
      std::string::size_type start_pos = 0;
      while((start_pos = str.find(from, start_pos)) != std::string::npos) {
        str.replace(start_pos, from.length(), to);
        start_pos += to.length(); // ...
      }
      return std::move(str);
    }
    
    std::string parse_string(char const * & data) {
      char const* start = data;
      while (*++data) {
        if (*data == '"' && (reverse_count(data-1, '\\') % 2) == 0) {
          return replace_all(std::string(start+1, data++), "\\\"", "\"");
        }
      }
      throw json::unterminated_json_exception("Could not locate end of string");
    }
  }
}