From: Martin DeMello <martindemello@...>
Date: 2006-12-05T13:38:26+09:00
Subject: Re: doubt with positive lookaround

On 12/5/06, hemant <gethemant@gmail.com> wrote:
> I do not understand behavior of positive look arounds in Ruby:
>
> chunked_data = "DIVex>##ECHO=b698fd4cc1ea4c7a4b5c4e1d1c402911##"
> p $& if chunked_data =~ /(?=DIVex)DI/            # =>  DI
>
> However,
>
> chunked_data = "<DIVex>##ECHO=b698fd4cc1ea4c7a4b5c4e1d1c402911##"
> p $& if chunked_data =~ /(?=<DIVex)DI/            # =>  nil
>
>
> does < gets treated as special character inside (?= ..) ?

No, but lookahead assertions are zero-width, so if your assertion
matches <DIV, your cursor is still before the <, and thus won't match
DI.  p $& if chunked_data =~ /(?=<DIVex)<DI/  works fine.

martin