On 4 April 2012 09:52, Bart Schaefer <schaefer@brasslantern.com> wrote:
> On Apr 3,  9:08pm, Jesper Nygårds wrote:
> }
> } /us<tab>
> }
> } whereas completion after an explicit cd is nearly instantaneous:
> }
> } cd /us<tab>
> }
> } It seems rather odd to me that coloring would render this so slow. I
> } suppose the delay is caused by zsh trying to color some list of
> } possible completions, but why would it be so very slow?
>
> /us<tab> as the first word in the buffer is in command position, so is
> completing any/all of commands, executables, builtins, functions,
> aliases, suffix-aliases, reserved-words, jobs and parameters.
>
> For each of these categories, _setup line 12 rebuilds the value of
> the _comp_colors array to add new patterns such that any pattern that
> started with '=' gets copied with a prefix matching the tag currently
> being tested; e.g. '(commands)=...' or '(jobs)=...'
>
> This is done even for tags that won't have any matches because the
> colors array has to be ready for the internals to use when a match is
> found, there's no way to "call back" to build it on demand.
>
> The expensive bit is that _comp_colors is declared as a unique array,
> so every time it gets rebuilt the resulting 1700+ entries are all
> compared against one another to make sure there is no duplication.
> Repeat that nine times and it takes a while.
>
> With "cd" in front, it's restricted to directories only, so the array
> is only rebuilt once.
>
> Addenda for -workers:
>
> Anybody want to have a stab at creating a vastly more efficient version
> of Src/params.c:arrayuniq() ?  I came up with a faster way to remove the
> duplicate elements, but the problem here is to efficiently determine
> that there are no duplicates to remove.  Perhaps throw the elements into
> a hash table and then make one pass looking up each element.
I wonder if the attached patch does what you want here. It is fairly
untested and incomplete as I have not been able to find out how to
make sure that search.h gets included.

-- 
VZ