From: "K.Kosako" <sndgk393@...>
Date: 2006-01-07T12:28:39+09:00
Subject: Re: Oniguruma lookbehind question

dblack@wobblini.net wrote:

> For some reason, lookbehind and alternation seem not to be playing
> together in a little Oniguruma test.  This is based on the string
> splitting thread from a little while ago this evening, and uses a CVS
> 1.9.0 Ruby acquired about 1/2 an hour ago.
>
>   str =  %Q{abc def "ghi jkl" mno}
>
>   # Look for "..." but just get the ... part:
>   re1 = /(?<=")[^"]+(?=")/
>
>   # Test that:
>   p str.scan(re1)  # => ["ghi jkl"]
>
>   # Now, do the same thing *or* \S+.  This should, I think,
>   # pick up the abc, def, and mno substrings too.
>
>   re2 = /((?<=")[^"]+(?="))|(\S+)/
>
>   # But it doesn't; the part before the alternation never
>   # matches, even though it did before (as shown by the
>   # captures):
>
>   p str.scan(re2)
>   # => [[nil, "abc"], [nil, "def"], [nil, "\"ghi"], [nil, "jkl\""],
>   #     [nil, "mno"]]
>
> I know that's all a bit cluttered, but the basic thing is that a
> sub-pattern using lookbehind doesn't seem to match any more when
> there's an alternation.  Instead, only the second alternative ever
> matches.

Is this pattern work for you?

str =  %Q{abc def "ghi jkl" mno}
re3 = /((?<=")[^"]+(?="))|([\S&&[^"]]+)/
p str.scan(re3)     #=> [[nil, "abc"], [nil, "def"], ["ghi jkl", nil], 
[nil, "mno"]]
--
K.Kosako