json_reader.cpp.svn-base

这是基于jsoncpp项目写扩展功能

bool 
Reader::readObject( Token &tokenStart )
{
   Token tokenName;
   std::string name;
   currentValue() = Value( objectValue );
   while ( readToken( tokenName ) )
   {
      bool initialTokenOk = true;
      while ( tokenName.type_ == tokenComment  &&  initialTokenOk )
         initialTokenOk = readToken( tokenName );
      if  ( !initialTokenOk )
         break;
      if ( tokenName.type_ == tokenObjectEnd  &&  name.empty() )  // empty object
         return true;
      if ( tokenName.type_ != tokenString )
         break;
      
      name = "";
      if ( !decodeString( tokenName, name ) )
         return recoverFromError( tokenObjectEnd );

      Token colon;
      if ( !readToken( colon ) ||  colon.type_ != tokenMemberSeparator )
      {
         return addErrorAndRecover( "Missing ':' after object member name", 
                                    colon, 
                                    tokenObjectEnd );
      }
      Value &value = currentValue()[ name ];
      nodes_.push( &value );
      bool ok = readValue();
      nodes_.pop();
      if ( !ok ) // error already set
         return recoverFromError( tokenObjectEnd );

      Token comma;
      if ( !readToken( comma )
            ||  ( comma.type_ != tokenObjectEnd  &&  
                  comma.type_ != tokenArraySeparator &&
		  comma.type_ != tokenComment ) )
      {
         return addErrorAndRecover( "Missing ',' or '}' in object declaration", 
                                    comma, 
                                    tokenObjectEnd );
      }
      bool finalizeTokenOk = true;
      while ( comma.type_ == tokenComment &&
              finalizeTokenOk )
         finalizeTokenOk = readToken( comma );
      if ( comma.type_ == tokenObjectEnd )
         return true;
   }
   return addErrorAndRecover( "Missing '}' or object member name", 
                              tokenName, 
                              tokenObjectEnd );
}


bool 
Reader::readArray( Token &tokenStart )
{
   currentValue() = Value( arrayValue );
   skipSpaces();
   if ( *current_ == ']' ) // empty array
   {
      Token endArray;
      readToken( endArray );
      return true;
   }
   int index = 0;
   while ( true )
   {
      Value &value = currentValue()[ index++ ];
      nodes_.push( &value );
      bool ok = readValue();
      nodes_.pop();
      if ( !ok ) // error already set
         return recoverFromError( tokenArrayEnd );

      Token token;
      if ( !readToken( token ) 
           ||  ( token.type_ != tokenArraySeparator  &&  
                 token.type_ != tokenArrayEnd ) )
      {
         return addErrorAndRecover( "Missing ',' or ']' in array declaration", 
                                    token, 
                                    tokenArrayEnd );
      }
      if ( token.type_ == tokenArrayEnd )
         break;
   }
   return true;
}


bool 
Reader::decodeNumber( Token &token )
{
   bool isDouble = false;
   for ( Location inspect = token.start_; inspect != token.end_; ++inspect )
   {
      isDouble = isDouble  
                 ||  in( *inspect, '.', 'e', 'E', '+' )  
                 ||  ( *inspect == '-'  &&  inspect != token.start_ );
   }
   if ( isDouble )
      return decodeDouble( token );
   Location current = token.start_;
   bool isNegative = *current == '-';
   if ( isNegative )
      ++current;
   Value::UInt threshold = (isNegative ? Value::UInt(-Value::minInt) 
                                       : Value::maxUInt) / 10;
   Value::UInt value = 0;
   while ( current < token.end_ )
   {
      Char c = *current++;
      if ( c < '0'  ||  c > '9' )
         return addError( "'" + std::string( token.start_, token.end_ ) + "' is not a number.", token );
      if ( value >= threshold )
         return decodeDouble( token );
      value = value * 10 + Value::UInt(c - '0');
   }
   if ( isNegative )
      currentValue() = -Value::Int( value );
   else if ( value <= Value::UInt(Value::maxInt) )
      currentValue() = Value::Int( value );
   else
      currentValue() = value;
   return true;
}


bool 
Reader::decodeDouble( Token &token )
{
   double value = 0;
   const int bufferSize = 32;
   int count;
   int length = int(token.end_ - token.start_);
   if ( length <= bufferSize )
   {
      Char buffer[bufferSize];
      memcpy( buffer, token.start_, length );
      buffer[length] = 0;
      count = sscanf( buffer, "%lf", &value );
   }
   else
   {
      std::string buffer( token.start_, token.end_ );
      count = sscanf( buffer.c_str(), "%lf", &value );
   }

   if ( count != 1 )
      return addError( "'" + std::string( token.start_, token.end_ ) + "' is not a number.", token );
   currentValue() = value;
   return true;
}


bool 
Reader::decodeString( Token &token )
{
   std::string decoded;
   if ( !decodeString( token, decoded ) )
      return false;
   currentValue() = decoded;
   return true;
}


bool 
Reader::decodeString( Token &token, std::string &decoded )
{
   decoded.reserve( token.end_ - token.start_ - 2 );
   Location current = token.start_ + 1; // skip '"'
   Location end = token.end_ - 1;      // do not include '"'
   while ( current != end )
   {
      Char c = *current++;
      if ( c == '"' )
         break;
      else if ( c == '\\' )
      {
         if ( current == end )
            return addError( "Empty escape sequence in string", token, current );
         Char escape = *current++;
         switch ( escape )
         {
         case '"': decoded += '"'; break;
         case '/': decoded += '/'; break;
         case '\\': decoded += '\\'; break;
         case 'b': decoded += '\b'; break;
         case 'f': decoded += '\f'; break;
         case 'n': decoded += '\n'; break;
         case 'r': decoded += '\r'; break;
         case 't': decoded += '\t'; break;
         case 'u':
            {
               unsigned int unicode;
               if ( !decodeUnicodeEscapeSequence( token, current, end, unicode ) )
                  return false;
               // @todo encode unicode as utf8.
	       // @todo remember to alter the writer too.
            }
            break;
         default:
            return addError( "Bad escape sequence in string", token, current );
         }
      }
      else
      {
         decoded += c;
      }
   }
   return true;
}


bool 
Reader::decodeUnicodeEscapeSequence( Token &token, 
                                     Location &current, 
                                     Location end, 
                                     unsigned int &unicode )
{
   if ( end - current < 4 )
      return addError( "Bad unicode escape sequence in string: four digits expected.", token, current );
   unicode = 0;
   for ( int index =0; index < 4; ++index )
   {
      Char c = *current++;
      unicode *= 16;
      if ( c >= '0'  &&  c <= '9' )
         unicode += c - '0';
      else if ( c >= 'a'  &&  c <= 'f' )
         unicode += c - 'a' + 10;
      else if ( c >= 'A'  &&  c <= 'F' )
         unicode += c - 'A' + 10;
      else
         return addError( "Bad unicode escape sequence in string: hexadecimal digit expected.", token, current );
   }
   return true;
}


bool 
Reader::addError( const std::string &message, 
                  Token &token,
                  Location extra )
{
   ErrorInfo info;
   info.token_ = token;
   info.message_ = message;
   info.extra_ = extra;
   errors_.push_back( info );
   return false;
}


bool 
Reader::recoverFromError( TokenType skipUntilToken )
{
   int errorCount = int(errors_.size());
   Token skip;
   while ( true )
   {
      if ( !readToken(skip) )
         errors_.resize( errorCount ); // discard errors caused by recovery
      if ( skip.type_ == skipUntilToken  ||  skip.type_ == tokenEndOfStream )
         break;
   }
   errors_.resize( errorCount );
   return false;
}


bool 
Reader::addErrorAndRecover( const std::string &message, 
                            Token &token,
                            TokenType skipUntilToken )
{
   addError( message, token );
   return recoverFromError( skipUntilToken );
}


Value &
Reader::currentValue()
{
   return *(nodes_.top());
}


Reader::Char 
Reader::getNextChar()
{
   if ( current_ == end_ )
      return 0;
   return *current_++;
}


void 
Reader::getLocationLineAndColumn( Location location,
                                  int &line,
                                  int &column ) const
{
   Location current = begin_;
   Location lastLineStart = current;
   line = 0;
   while ( current < location  &&  current != end_ )
   {
      Char c = *current++;
      if ( c == '\r' )
      {
         if ( *current == '\n' )
            ++current;
         lastLineStart = current;
         ++line;
      }
      else if ( c == '\n' )
      {
         lastLineStart = current;
         ++line;
      }
   }
   // column & line start at 1
   column = int(location - lastLineStart) + 1;
   ++line;
}


std::string
Reader::getLocationLineAndColumn( Location location ) const
{
   int line, column;
   getLocationLineAndColumn( location, line, column );
   char buffer[18+16+16+1];
   sprintf( buffer, "Line %d, Column %d", line, column );
   return buffer;
}


std::string 
Reader::getFormatedErrorMessages() const
{
   std::string formattedMessage;
   for ( Errors::const_iterator itError = errors_.begin();
         itError != errors_.end();
         ++itError )
   {
      const ErrorInfo &error = *itError;
      formattedMessage += "* " + getLocationLineAndColumn( error.token_.start_ ) + "\n";
      formattedMessage += "  " + error.message_ + "\n";
      if ( error.extra_ )
         formattedMessage += "See " + getLocationLineAndColumn( error.extra_ ) + " for detail.\n";
   }
   return formattedMessage;
}


std::istream& operator>>( std::istream &sin, Value &root )
{
    Json::Reader reader;
    bool ok = reader.parse(sin, root, true);
    //JSON_ASSERT( ok );
    if (!ok) throw std::runtime_error(reader.getFormatedErrorMessages());
    return sin;
}


} // namespace Json