Re: [Firebird-devel] How do I get an accurate list of sql keywords?

[Mike N. <ta...@al...>]

Ann W. Harrison wrote:

> How would rdb$sql_keywords be implemented?

Dear god, a wild idea that's getting implementation questions this fast! :-)

I think it would make most sense to have this as some kind of on-the-fly
generated data from the hard-coded keyword set. Putting it in a DB (on-disk)
makes no sense to me. This is static hard-coded information about the
engine, not the DB.

struct "tok" (dsql/keywords.h) should then also probably gain another
member, telling what conformance level the keyword have. Probably a simpe
enum would suffice, but maybe a bitfield could fit better if there are some
bits we would like to OR together (like telling if the keyword it's both
SQL_92 and ... whatever? I don't know).

As for the resulting virtual table presented from such a select the first
field is obvious:
KEYWORD
An integral field VERSION (DIALECT?)?

After that it kind of depends on if the ORing of bits together seems like a
good idea or not. If not, a simple string field could suffice. If ORing is
accepted I'd however be more reluctant to that approach, since the resulting
field could possibly become quite a few characters when needing to append a
bunch of strings. Maybe instead map the bits 1:1 to a bunch of BOOLean
result set fields in that case? Allowing stuff like:

select KEYWORD from RDB$KEYWORDS where ANSI92=TRUE AND <whatever>=FALSE;

Then again, maybe this would be overdoing it?

> Could users add, delete, update keywords?

I'd hope not. It would become a rather interesting situation if a user added
a new keyword, without any option to tell neither the parser nor the lexical
analyzer 1) where the keyword fits, 2) what it's supposed to do. :-)


/Mike