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[REBOL] Re: Matching RE's

From: jelinem1:nationwide at: 23-Mar-2001 8:43

>> find/case/any/match "user.r" "*.r"
== ".r"
>> find/case/any/match "user.r" "*^.r"
== ".r"
>> find/any/match "user.r" "*.r"
== ""
>> index? find/any/match "user.r" "*.r"
== 7 /case seems to be presenting a problem. You might try viewing just the return from 'find, and getting this 'index, to see what is happening in abit more detail. Hopefully this will help you understand what is going on.
>> find/case/any/match "user qwerty r" "*gargler"
== none
>> find/case/any/match "user qwerty r" "*garglr"
== ""
>> find/case/any/match "user qwerty r" "*ggly"
== " r" That totally boggles my mind. After staring at it for awhile I can almost see what it's doing, but it's certainly not the behavior I initially expected. - Michael Jelinek Marcus Petersson <[d4marcus--dtek--chalmers--se]> on 03/22/2001 04:53:33 PM From: Marcus Petersson <[d4marcus--dtek--chalmers--se]> on 03/22/2001 04:53 PM Please respond to [rebol-list--rebol--com] Sent by: [rebol-bounce--rebol--com] To: [rebol-list--rebol--com] cc: Subject: [REBOL] Matching RE's Warning! This mail contains a lot of whining. Don't read it if you easily get bored. You have been warned, so bear with me. Ok, so I start out thinking this will work:
>> "" = find/case/any/match "user.r" "*.r"
== false Hmm, so the dot is a wildcard (equal to ?) and needs to be escaped:
>> "" = find/case/any/match "user.r" "*^.r"
== false So it didn't work, let's try another RE construct: = find/case/any/match "user.r" "*[.]r" == true Aha, that looks better, but let's check it first:
>> "" = find/case/any/match "user" "*[.]r"
== true Oh no! The dot is still acting as a wildcard. What to do now? Perhaps we can escape it within the blocks:
>> "" = find/case/any/match "user" "*[^.]r"
== true Nope, didn't work. Let's try something else:
>> "" = find/case/any/match "user" "*[\.]r"
== false
>> "" = find/case/any/match "user.r" "*[\.]r"
== true Aha, this could be it! But wait, perhaps... :
>> "" = find/case/any/match "user\r" "*[\.]r"
== true Ouch, it seems to be a choice between backslash and dot. Or is it?
>> "" = find/case/any/match "user r" "*[\.]r"
== true AARGH! Does it even work at all?
>> "" = find/case/any/match "user qwerty r" "*[ gargle ]r"
== true Double-AARGH! Oh well, whatever those brackets do, I better stop using them. Let's see... :
>> "" = find/case/any/match "user qwerty r" "*gargler"
== false Phew, I was starting to worry. Let's check again:
>> "" = find/case/any/match "user qwerty r" "*garglr"
== true What???!!! Oh well, before we give, better check the PDF. Hmm, seems they have put /match before /any there. Wonder why... :
>> "" = find/case/match/any "user qwerty r" "*garglr"
== true Nope. Oh well, one last try:
>> "" = find/match/any "user qwerty r" "*garglr"
== false Yes! This is it, it was a problem with /case. So we get:
>> "" = find/match/any "user.r" "*.r"
== true
>> "" = find/match/any "user" "*.r"
== false Good good. On the other hand, we also get:
>> "" = find/match/any "user.r" "*.R"
== true Not good. What if we put /case back in there:
>> "" = find/match/any/case "user.r" "*.R"
== false
>> "" = find/match/any/case "user.r" "*.r"
== false And so we're back where we started. Sigh, I guess I better write a RE to Rebol parserule translator. Unless such a thing exists already...? Some other examples:
>> find/case/any "user.R" '*r.R
== none
>> find/case/any "user.R" '*r.*
== none
>> find/case/any "user.R" '*r.r
== "user.R"
>> find/case/any "user.R" '*r.?
== "user.R" Only the last one is correct. That pretty much says it all. Marcus ------------------------------------ If you find that life spits on you calm down and pretend it's raining