Re: Ltree syntax improvement

Nikita Glukhov <n.gluhov@postgrespro.ru> writes:
> Attached new version of the patch.

I spent a little bit of time looking through this, and have a few
comments:

* You have a lot of places where tests for particular ASCII characters
are done like this:

	if ((charlen == 1) && t_iseq(src, '\\'))

This is a tedious and expensive way to spell

	if (*src == '\\')

because charlen is necessarily 1 if you are looking at an ASCII character;
there is no allowed backend encoding in which an ASCII character can be
the first byte of a multibyte character.  Aside from the direct
simplifications of the tests that this makes possible, I see some places
where you'd not have to pass charlen around, either.

* I spent a fair amount of time thinking that a lot of the added code
was wrong because it was only considering escaping and not
double-quoting.  I eventually concluded that the idea is to convert
double-quoting to a pure escape-based representation during input
and store it that way.  However, I don't really see why that is either
necessary or a good idea --- the internal storage already has a length
counter for each label.  So I think what you really ought to be doing
here is simplifying out both quotes and escapes during ltree_in
and just storing the notionally-represented string internally.
(If I've misunderstood what the plan is, well the utter lack of
documentation in the patch isn't helping.)

* The added test cases seem a bit excessive and repetitive.

			regards, tom lane