non-greedy regexp

non-greedy regexp

[Robert Pontisso]

Hi. I've been having difficulty finding a non-greedy
regular expression to match a single instance of an
xml-type tag pair in a line.  Given a line with
several instances of <foo>...</foo>, is there a
version of <foo>.*</foo> that won't match everything
between the beginning of the first pair and closing of
the last pair?

Thanks


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Re: non-greedy regexp

[Michaël Cadilhac]

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Robert Pontisso <rpontisso@yahoo.co.uk> writes:

> Hi.  I've  been  having  difficulty  finding  a  non-greedy  regular
> expression to  match a  single instance of  an xml-type tag  pair in
> a line.  Given a line  with several instances of  <foo>...</foo>, is
> there a version of <foo>.*</foo> that won't match everything between
> the beginning of the first pair and closing of the last pair?

Is «<foo>.*?</foo>» what you're looking for?

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Re: non-greedy regexp

[David Kastrup]

Robert Pontisso <rpontisso@yahoo.co.uk> writes:

> Hi. I've been having difficulty finding a non-greedy
> regular expression to match a single instance of an
> xml-type tag pair in a line.  Given a line with
> several instances of <foo>...</foo>, is there a
> version of <foo>.*</foo> that won't match everything
> between the beginning of the first pair and closing of
> the last pair?

Well, <foo>.*?</foo> would be one possibility, but that does not cover
nested tags.  You'd probably want something like

(let ((level 0))
  (while (progn
           (search-forward-regexp "<\\(/\\)?foo>")
           (setq level (if (match-beginning 1) (1- level) (1+ level)))
           (> 0 level))))

in order to match nested tags.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum