From: Markus Jais <mjais@...>
Date: 2002-02-13T22:54:21+09:00
Subject: Re: simple XML parsing (greedy / non-greedy

On Wed, 13 Feb 2002 13:49:51 +0100, Ron Jeffries wrote:

> On Wed, 13 Feb 2002 12:06:49 GMT, David Alan Black
> <dblack@candle.superlink.net> wrote:
> 
>>On Wed, 13 Feb 2002, Ron Jeffries wrote:
>>
>>> Suppose I had this text
>>>
>>> 	'<a>this is a</a><a>this is a also</a>'
>>>
>>> and I wanted to write a regexp that would match the tag <a>..</a> and
>>> return
>>>
>>> 	'this is a'
>>> 	(not 'this is a</a><a>this is a also')
>>>
>>> I'd sort of like to use a pattern like
>>>
>>> Regexp.new( '<a>(.*)</a>' ), but this is greedy and matches as far as
>>> it can.
>>>
>>> Is there a way to tell the match operator to stop on the earliest
>>> match?
>>
>>Yes -- just use *? instead of *
> 
> Thanks ... I see that that works. But I don't see why. Once the ? is in
> effect, does the whole regexp become non-greedy and quit on the first
> match? (This must be approximately the case, or it wouldn't be working.)
> 
> Anyway, thanks ... if I treat it as magic it'll work.
> 
> What should I have read to know this?

the ? affects only the "*" not the whole regexp.
you should find this in the pickaxe book in the chapter "Standard Types"

markus


> 
> Thanks!
> 
> Ronald E Jeffries
> http://www.XProgramming.com
> http://www.objectmentor.com
> I'm giving the best advice I have. You get to decide whether it's true
> for you.