code: @Override
  	public TokenType next() {
  		if (position >= sql.length()) {
  			token = null;
  			tokenType = TokenType.EOF;
  			nextTokenType = TokenType.EOF;
  			return tokenType;
  		}
  		switch (nextTokenType) {
  		case SQL:
  			parseSql();
  			break;
  		case COMMENT:
  			parseComment();
  			break;
  		case ELSE:
  			parseElse();
  			break;
  		case BIND_VARIABLE:
  			parseBindVariable();
  			break;
  		default:
  			parseEof();
  			break;
  		}
  		return tokenType;
  	}
docs: {@inheritDoc}
  
  @see jp.co.future.uroborosql.parser.SqlTokenizer#next()