Hi Dan,
At this point, since you prefer to work in your own repository [0], I cannot add line comments via Github so I'll send my comments to this list.
Please explain why in [1] you are using uppercase. This should be only for constants.
[0] https://github.com/udan11/sql-parser
[1] https://github.com/udan11/sql-parser/blob/master/src/Parser.php#L19