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bug#2881: 23.0.91; inconsistent regexps with "explicitly numbered group


From: Joe Corneli
Subject: bug#2881: 23.0.91; inconsistent regexps with "explicitly numbered group"
Date: Fri, 3 Apr 2009 17:38:30 -0400

Oh, OK, I see! Never mind!

On Fri, Apr 3, 2009 at 5:32 PM, Andreas Schwab <address@hidden> wrote:
> Andreas Schwab <address@hidden> writes:
>
>> Joe Corneli <address@hidden> writes:
>>
>>> Please execute the following forms with C-x C-e.  Form 1
>>> and Form 3 return `t' (Yes, we are looking at the
>>> indicated regular expression), whereas Form 2 returns
>>> `nil' (even though from the Elisp reference page "34.3.1.3
>>> Backslash Constructs in Regular Expressions", it appears
>>> that this form ought to return `t' like the others).
>>
>>      `\|' applies to the largest possible surrounding expressions.
>>      Only a surrounding `\( ... \)' grouping can limit the grouping
>>      power of `\|'.
>>
>>> (let ((possible-environments
>>>        "\\(?1:lisp\\)\\|\\(?1:idea\\)\\|\\(?1:common\\)") )
>>>       (looking-at
>>>             (concat "\n*?\\\\begin{"
>>>                     possible-environments
>>>                     "}")))
>>
>>
>> The three alternatives of this regexp are "\n*?\\\\begin{\\(?1:lisp\\)",
>> "\\(?1:idea\\)" and "\\(?1:common\\)".
>
> The last one is "\\(?1:common\\)}", of course.
>
> Andreas.
>
> --
> Andreas Schwab, address@hidden
> GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
> "And now for something completely different."
>






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