Re: [PATCH 2/5] pathspec: add tree_recursive_diff parameter

Nguyen Thai Ngoc Duy [off-list ref] writes:

2010/9/28 Junio C Hamano [off-list ref]:

quoted

Nguyễn Thái Ngọc Duy [off-list ref] writes:
...

quoted

 - If it's recursive diff, directories are just an intermediate step.
   All path must end with a file name. Thus, directories will be
   unconditionally matched.

Hmm, I am not sure what you mean by this.  If the pathspec says a/b*/c,
you are in "a" and are deciding if you should descend to its subdirectory,
then you would surely want to be able to say:

 (1) Ah, the subdirectory I am looking at is "bar" and it does match "b*".
     It might contain "c"; I should descend into it.

 (2) Nope, the subdirectory I am looking at is "frotz" and it can never
     match "b*", so there is no point recursing into it.

I did not go that far, trying to analyse the pattern. When I wrote
"immediate step" I was thinking of "*foo" pattern, which effectively
means descending to any reachable directories because '*' matches
slashes too. I think that's the worst case.

Anyway I did not know that I could borrow some optimizations from
pathspec_matches() in builtin/grep.c.

As you noticed, over time we have polished our re-implementations of the
pathspec logic to avoid needlessly descending into subdirectories, and the
one in the grep may be the latest incarnation of it.  The logic that uses
the path_simplify structure in dir.c may also offer you some inspirations.

Note that the worst case will fall out as a natural consequence of doing
the fallback in the dumb and simple way, so you do not have to worry too
much about it ;-)  I would prefer to see the new, consolidated logic to at
least know the easy optimizations we already have.

Thanks.