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Re^3: Interesting behavior of regular expression engine

by 7stud (Deacon)
on Mar 14, 2013 at 07:48 UTC ( #1023410=note: print w/replies, xml ) Need Help??


in reply to Re^2: Interesting behavior of regular expression engine
in thread Interesting behavior of regular expression engine

What's not well-defined is what steps the underlying implementation takes to arrive at the output,

Yet, "Programming Perl 3rd" lays out 6 very complicated rules describing in detail how the regex engine proceeds (p 197-201). So, Larry at least thinks the steps are/were well defined. I wonder if those steps are in the new edition?
  • Comment on Re^3: Interesting behavior of regular expression engine

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Re^4: Interesting behavior of regular expression engine
by Anonymous Monk on Mar 14, 2013 at 08:00 UTC

    So, Larry at least thinks the steps are well defined.

    I don't know what you're talking about, but that book is 12 years old at least, and larry himself hasn't touched the regex engine in about as long , optimizations have been added, things have changed

      Ok, I've read the rules in 5.9.4. The Little Engine That /Could(n't)?/ and they are prefaced with for this discussion we're pretending the optimizer doesn't exist. , pretty much what we've been saying

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[choroba]: Why don't they use tire chains?
[perldigious]: First snow, probably not prepared right away choroba.
[stevieb]: it's Quebec... they do weird stuff there :) In the mountains, it is *mandatory* for trucks to use tire chains. Many passenger vehicles do as well (but it's not mandatory for them)
[perldigious]: That stuff can hit fast... like what we just got where I'm at. Saw a few people who had slid OUT of the roundabout I have to drive through to get to work, not used to the ice yet, take awhile to get the hang of it again and make vehicle adjustments.
[stevieb]: man, when the roads are glare ice, I don't even bother going to work or out... unless I absolutely have to, or was already out in the first place
[choroba]: Tire chains are mandatory here in mountains, and the only unprepared each year are gritters
[stevieb]: I have a 3 day winter survival kit in my vehicle in the event I get snowed in in the mountains (which has happened before due to avalanches closing the roads (and once in the summer due to a massive forest fire that trapped us
[perldigious]: a handful of people in my work area did not make it, but I live pretty close and it's flat the whole way, so I didn't have any trouble. The roundabout is the worst thing I have to negotiate.
[thezip]: G'day all!
[perldigious]: Well, that and dodging the people who forget how ice works right away. :-)

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