Fixes 649 to add support for HOUR, MINUTE, SECOND date literals and s…

[thebiguno]

…upport for identifiers as the interval parameter.

See my comments in issue #649.

If you add <S_IDENTIFIER> to the line ( token=<S_LONG> | token=<S_DOUBLE> | token=<S_CHAR_LITERAL> | token = <S_IDENTIFIER>) it fixes many of the issues we are seeing (most of the time we use a single identifier as the offset value; it is a less frequent case that we use an expression).

A test case for this scenario is:

select current_date + foo day as next_day from foo

It still does not work for expressions. I tried adding support for an expression directly there, but it gives a left parse error when reading the .jj file. I tried wrapping the expression in brackets (accepted but not required in DB2), and everything compiled but tests started to fail - it looks like the parser was getting confused.

Anyway, the S_IDENTIFIER change works for most of our reports. There are now only 11 out of 1553 reports which fail to parse.

[coveralls]

Coverage decreased (-0.2%) to 83.748% when pulling 6ddc584 on thebiguno:master into c85e79b on JSQLParser:master.