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Re: simple regex pattern sought

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On 5/26/2012 2:07 PM, Lew wrote:
> markspace wrote:
>> Lew wrote:
>>> Use a regex like "[\"'][^\"']+[\"']" is one way. The cleanest? I
>>> don't know.
>>>
>> This would match "John's restaurant" as "John'.
>>
>> The first quote matches ", John does not contain either ' or " as
>> specified,
>> and the last character class matches the '. Not I think what is wanted.
>
> As I correct6ed in my very next post.
>


Unfortunately that one doesn't work either.  The central part, [^"'], 
doesn't allow a match of a ' if the starting delimiter was a ", and that 
doesn't match Roedy's spec.  "John's restaurant" wouldn't be matched at 
all, because the matcher couldn't match past the ' to get to the ".

I think the easiest is to write out a grammar for the expression, then 
translate to regex.

QUOTED_STRING := SQUOTED_STRING | DQUOTED_STRING

SQUOTED_STRING := ' NON_S_QUOTE + '

DQUOTED_STRING := " NON_D_QUOTE + "

NON_S_QUOTE := [^']

NON_D_QUOTE := [^"]

At this point the grammar is very clear.  (Note I haven't included 
Robert's \x escape sequences.)  I think it's worth learning to use antlr 
rather than regex, which tends to obfuscate more than it helps. 
However, a literal translation into regex isn't hard, and a literal 
translation avoids mis-optimizations.

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Thread

simple regex pattern sought Roedy Green <see_website@mindprod.com.invalid> - 2012-05-25 14:45 -0700
  Re: simple regex pattern sought markspace <-@.> - 2012-05-25 14:55 -0700
  Re: simple regex pattern sought Lew <lewbloch@gmail.com> - 2012-05-25 14:55 -0700
    Re: simple regex pattern sought markspace <-@.> - 2012-05-25 15:04 -0700
      Re: simple regex pattern sought Lew <noone@lewscanon.com> - 2012-05-26 14:07 -0700
        Re: simple regex pattern sought markspace <-@.> - 2012-05-26 18:34 -0700
          Re: simple regex pattern sought Lew <noone@lewscanon.com> - 2012-05-27 11:39 -0700
    Re: simple regex pattern sought Lew <lewbloch@gmail.com> - 2012-05-25 15:03 -0700
    Re: simple regex pattern sought Robert Klemme <shortcutter@googlemail.com> - 2012-05-26 00:12 +0200
      Re: simple regex pattern sought markspace <-@.> - 2012-05-25 18:43 -0700
        Re: simple regex pattern sought Robert Klemme <shortcutter@googlemail.com> - 2012-05-26 16:37 +0200
          Re: simple regex pattern sought markspace <-@.> - 2012-05-26 08:06 -0700
            Re: simple regex pattern sought Robert Klemme <shortcutter@googlemail.com> - 2012-05-26 17:34 +0200
              Re: simple regex pattern sought Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-05-26 10:07 -0700
      Re: simple regex pattern sought Roedy Green <see_website@mindprod.com.invalid> - 2012-05-26 06:19 -0700
        Re: simple regex pattern sought markspace <-@.> - 2012-05-26 07:19 -0700
        Re: simple regex pattern sought markspace <-@.> - 2012-05-26 07:57 -0700
          Re: simple regex pattern sought Robert Klemme <shortcutter@googlemail.com> - 2012-05-26 17:13 +0200
            Re: simple regex pattern sought markspace <-@.> - 2012-05-26 10:08 -0700
              Re: simple regex pattern sought Roedy Green <see_website@mindprod.com.invalid> - 2012-05-26 14:14 -0700

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