[sf-perl] The SF Perl Raku Study Group, 03/28 at 1pm PDT

[Joseph Brenner]

Yes, I see almost 40% improvement as well (~36%).

I see I inadvertently concealed where <ruler> is by making it part of
<control_2> for no particular reason...



On 3/29/21, yary <not.com at gmail.com> wrote:
> Took me a bit of looking, but the issue is in the details- the decision
> character for "stuff" is '-' since that is always the beginning of "ruler",
> the first regex under "control_2" which is the first regex following
> "stuff". Changing to "-" and re-ordering the stuff regex fixes the
> proof-of-concept, and speeds it up roughly 40% on my system.
>
>     regex stuff
>     {
>         [            # stuff is a group of either
>             <-[-]>+: # a ratcheting string of non-decision points. Removing
> ratcheting makes it hang on Yary's system.
>           ||         # or
>             '-'      # a "dash" decision point
>         ]*           # 0-many of those. Greedy or non-greedy both work,
> about the same speed.
>     }  # end regex
>
> Will commit this soon.
>
> (and thanks for making this runnable & pointing out that I can use your
> test files all in the repo)
>
> -y
>
>
> On Mon, Mar 29, 2021 at 8:07 PM Joseph Brenner <doomvox at gmail.com> wrote:
>
>> That's interesting thinking... I've been playing around with the idea
>> over here, but haven't got it to work (it fails to parse):
>>
>>
>> https://github.com/doomvox/raku-study/blob/main/bin/2021mar28/doomfiles_browse_sequence-iii.raku
>>
>> This version does work-- just using greedy matching on "stuff" makes
>> it use orders-of-magnitude less resources:
>>
>>
>> https://github.com/doomvox/raku-study/blob/main/bin/2021mar28/doomfiles_browse_sequence-ii.raku
>>
>>
>> And yes, I would guess that the non-greedy matching probably works
>> here because the following material is effectively pinned at the end
>> of the document.
>>
>> Note that you should be able to run these scripts as written, provided
>> you also pull copies of these source files:
>>
>> https://github.com/doomvox/raku-study/tree/main/dat/doomfiles
>>
>>
>>
>> On 3/29/21, yary <not.com at gmail.com> wrote:
>> > Hi Joe & other Raku study group attendees,
>> >
>> > At the time I left, we were looking at a grammar with a speed-memory
>> issue
>> > on large-ish files. I had a germ of an idea which I couldn't express,
>> > and
>> > from the meeting notes I see you have a simple fix *"by changing stuff
>> > regex (.\*?) to non-greedy (.\*)*" I suspect the greedy-optimization
>> works
>> > because the thing after the "stuff" regex is near the end of the file.
>> Thus
>> > if instead it was close to the beginning, it would have a similar issue
>> > with greedy and non-greedy would fix.
>> >
>> > With a night to sleep on it, the thing I was thinking & trying to say
>> > is
>> > that, in the specialized HTML-grammar you had, the decision points are
>> all
>> > at left-brackets. By re-writing "stuff" so that it will only backtrack
>> when
>> > it hits a bracket, I expect more speed-memory gains.
>> >
>> > How well does this perform vs the simple .* greedy fix?
>> >
>> >     regex stuff
>> >     { (  # capture stuff (positional capture might not be needed)
>> >         [               # Stuff is a group of either
>> >             \<          # a left-bracket decision point
>> >           ||            # or
>> >             <-[ \< ]>+: # a ratcheting string of non-decision points
>> >         ]*              # 0-many of those. Greedy or non-greedy both
>> work?
>> >     ) }  # end capture, end regex
>> >
>> > This was harder to express verbally & in code than I expected!
>> >
>> > -y
>> >
>> >
>> > On Sun, Mar 28, 2021 at 4:23 PM Joseph Brenner <doomvox at gmail.com>
>> wrote:
>> >
>> >> I did send this one out, but it doesn't seem that it went out exactly,
>> >> so let's try this one more time.   The Study Group is happening,
>> >> already in progress, though we'll be taking a break next week and
>> >> broadcasting a burning yule log with the soundtrack to Jesus Christ
>> >> Superstar.  (Just kidding)
>> >>
>> >>
>> >> Flaming Carrot, "Night Patrol" (1986) by Bob Burden:
>> >>
>> >>     I feel it rising now...
>> >>     ... like little bubbles...
>> >>     THE MOON IS FULL...
>> >>     ... in a full moon, your brain floats to top of your head...
>> >>     I feel it...
>> >>     beginning to boil...
>> >>     a lot will happen tonight.
>> >>
>> >> The Raku Study Group
>> >>
>> >> March 28, 2021  1pm in California, 8pm in the UK
>> >>
>> >> Zoom meeting link:
>> >>
>> >>
>> https://us02web.zoom.us/j/81127128506?pwd=N0I5bkxUZTRLaWwxN2RJTGlsT254QT09
>> >>
>> >> Passcode: 4RakuRoll
>> >>
>> >> RSVPs are useful, though not needed:
>> >>   https://www.meetup.com/San-Francisco-Perl/events/277163968/
>> >> _______________________________________________
>> >> SanFrancisco-pm mailing list
>> >> SanFrancisco-pm at pm.org
>> >> https://mail.pm.org/mailman/listinfo/sanfrancisco-pm
>> >>
>> >
>>
>