Re: Making tab-complete.c easier to maintain

On Sun, Dec 20, 2015 at 6:24 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> 1. I think it would be a good idea to convert the matching rules for
> backslash commands too. To do that, we'd need to provide a case-sensitive
> equivalent to word_match and the matching macros. I think we'd also have
> to extend word_match to allow a trailing wildcard character, maybe "*".
>
> 2. I believe that a very large fraction of the TailMatches() rules really
> ought to be Matches(), ie, they should not consider matches that don't
> start at the start of the line. And there's another bunch that could
> be Matches() if the author hadn't been unaccountably lazy about checking
> all words of the expected command. If we converted as much as we could
> that way, it would make psql_completion faster because many inapplicable
> rules could be discarded after a single integer comparison on
> previous_words_count, and it would greatly reduce the risk of inapplicable
> matches. We can't do that for rules meant to apply to DML statements,
> since they can be buried in WITH, EXPLAIN, etc ... but an awful lot of
> the DDL rules could be changed.
>
> 3. The HeadMatches macros are pretty iffy because they can only look back
> nine words. I'm tempted to redesign get_previous_words so it just
> tokenizes the whole line rather than having an arbitrary limitation.
> (For that matter, it's long overdue for it to be able to deal with
> multiline input...)
>
> I might go look at #3, but I can't currently summon the energy to tackle
> #1 or #2 --- any volunteers?

I could have a look at both of them and submit patch for next CF, both
things do not seem that much complicated.
--
Michael