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Re: Newbie regexp question


From: Michael Slass
Subject: Re: Newbie regexp question
Date: Wed, 30 Oct 2002 21:37:01 GMT
User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2

Michael Slass <address@hidden> writes:

>Friedrich Dominicus <address@hidden> writes:
>
>>Michael Slass <address@hidden> writes:
>>
>>> 
>>> I think a lisp program would do better at this:
>>> 
>>> VERY LIGHTLY TESTED.  MAKE BACKUPS BEFORE EXPERIMENTING WITH THIS!
>>> 
>>> (defun paulc-purge-html-test-sections (buffer)
>>>   "Delete all occurances of text between <!--Test--> and <!--End of 
>>> Test-->, inclusive."
>>>   (interactive "bPurge html test sections in buffer: ")
>>>   (save-excursion
>>>     (save-restriction
>>>       (goto-char (point-min))
>>>       (while (re-search-forward "<!--Test-->" nil t)
>>>         (let ((beg (match-beginning 0))
>>>               (end (progn (re-search-forward "<!--End of Test-->" nil t)
>>>                           (match-end 0))))
>>>           (if end
>>>               (kill-region beg end)
>>>             (error "Unmatched \"<!--Test-->\" sequence at position %d" 
>>> beg)))))))

>>However a really nice solution anyway I think there is a problem with
>>the end stuff. 
>>
>>The info pages say:
>>  Search forward from point for regular expression REGEXP.
>>  Set point to the end of the occurrence found, and return point.
>>
>>That means you will return the End tags too,

There *is* a problem with the end -- the (progn ...) should be (and ...)
so that end will be nil if the ending tag isn't found.  I forgot that
(match-end) would keep the value of the last successful match.

         (let ((beg (match-beginning 0))
               (end (and (re-search-forward "<!--End of Test-->" nil t)
                         (match-end 0))))


-- 
Mike Slass


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