Re: [PATCH v5 3/3] ls-files.c: add --deduplicate option

[胡哲宁 <adlternative@gmail.com>]

Junio C Hamano <gitster@pobox.com> 于2021年1月22日周五 上午4:45写道：
>
> 胡哲宁 <adlternative@gmail.com> writes:
>
> >> OK.  When show_stage is set, skipping_duplicates is automatically
> >> turned off (and show_unmerged is automatically covered as it turns
> >> show_stage on automatically).  So this feature has really become
> >> "are we showing only names, and if so, did we show an entry of the
> >> same name before?".
> > Yeah,showing only names,so I yesterday ask such question :)
> >>
> >> >                       if (!show_unmerged || ce_stage(ce))
> >> >                               show_ce(repo, dir, ce, fullname.buf,
> >> >                                       ce_stage(ce) ? tag_unmerged :
> >> >                                       (ce_skip_worktree(ce) ? tag_skip_worktree :
> >> >                                               tag_cached));
> >> > +                     if (show_cached && skipping_duplicates)
> >> > +                             last_shown_ce = ce;
> >>
> >> The code that calls show_ce() belonging to a totally separate if()
> >> statement makes my stomach hurt---how are we going to guarantee that
> >> "last shown" really will keep track of what was shown last?
> >>
> >> Shouldn't the above be more like this?
> >>
> >> -                       if (!show_unmerged || ce_stage(ce))
> >> +                       if (!show_unmerged || ce_stage(ce)) {
> >>                                 show_ce(repo, dir, ce, fullname.buf,
> >>                                         ce_stage(ce) ? tag_unmerged :
> >>                                         (ce_skip_worktree(ce) ? tag_skip_worktree :
> >>                                                 tag_cached));
> >> +                               last_shown_ce = ce;
> >> +                       }
> >>
> > well,I am also thinking about this question :"last_shown_ce" is not true
> > last shown ce,but may be If "last_shown_ce" truly seen every last shown
> > ce ,We may need more cumbersome logic to make the program correct.
> > I have tried the processing method of your above code before, but found
> >  that some errors may have occurred.
>
> I think judicious use of "goto" without introducing the last_shown
> would probably result in a much more maintainable code.  It may look
> somewhat like so:
>
>         for (i = 0; i < repo->index->cache_nr; i++) {
>                 const struct cache_entry *ce = repo->index->cache[i];
>                 struct stat st;
>                 int stat_err;
>
>                 construct_fullname(&fullname, repo, ce);
>
>                 if ((dir->flags & DIR_SHOW_IGNORED) &&
>                         !ce_excluded(dir, repo->index, fullname.buf, ce))
>                         continue;
>                 if (ce->ce_flags & CE_UPDATE)
>                         continue;
>                 if ((show_cached || show_stage) &&
>                     (!show_unmerged || ce_stage(ce))) {
>                         show_ce(repo, dir, ce, fullname.buf,
>                                 ce_stage(ce) ? tag_unmerged :
>                                 (ce_skip_worktree(ce) ? tag_skip_worktree :
>                                  tag_cached));
>                         if (skip_duplicates)
>                                 goto skip_to_next_name;
>                 }
>
>                 if (!show_deleted && !show_modified)
>                         continue;
>                 if (ce_skip_worktree(ce))
>                         continue;
>                 stat_err = lstat(fullname.buf, &st);
>                 if (stat_err && (errno != ENOENT && errno != ENOTDIR))
>                         error_errno("cannot lstat '%s'", fullname.buf);
>
>                 if (show_deleted) {
>                         show_ce(repo, dir, ce, fullname.buf, tag_removed);
>                         if (skip_duplicates)
>                                 goto skip_to_next_name;
>                 }
>                 if (show_modified &&
>                     (stat_err || ie_modified(repo->index, ce, &st, 0)))
>                         show_ce(repo, dir, ce, fullname.buf, tag_modified);
>                 continue;
>
>         skip_to_next_name:
>                 {
>                         int j;
>                         const struct cache_entry **cache = repo->index->cache;
>                         for (j = i + 1; j < repo->index->cache_nr; j++)
>                                 if (strcmp(ce->ce_name, cache[j]->ce_name))
>                                         break;
>                         i = j - 1; /* compensate for outer for loop */
>                 }
>         }
I have to admit that this is indeed a good way to skip with "goto".
Thanks for your help.
And should I still use gitgitgadget PR on my origin branch "dedup"or
send patch on branch "zh/ls-files-deduplicate"?