From: Robert Dober <robert.dober@...>
Date: 2009-07-22T17:13:03+09:00
Subject: Re: String spliting and inclusion

On 7/22/09, David A. Black <dblack@rubypal.com> wrote:
> Hi --
>
>
>  On Wed, 22 Jul 2009, Stuart Clarke wrote:
>
>
> > Hi all,
> >
> > I am having trouble working out some logic for my problem. I basically
> > have a long string (320 characters) and I want to split into smaller
> > strings no longer than 50 characters in length. At present I have the
> > following regex:
> >
> > data = "big long string"
> >
> > puts data.scan(/{50}/)
> >
> > This nicely breaks up the string however there are a few problems with
> > it, including:
> >
> > It only outputs 50 character chunks, therefore when it gets to the end
> > and only 20 characters remain it misses them off the output (it outputs
> > 6 50 characters strings and ignores the remaining 20)
> >
> > This regex also splits up words, which is something I don't want. I want
> > a script to count to 50 and when it gets there, go backwards to find
> > some white space and split it at that point, therefore not breaking up a
> > word. As a result a number of sub strings of various sizes will be
> > created all less than 50 chars.
> >
> > I hope this makes sense, to summarise I want to break up a string into a
> > max of 50 characters without breaking up words.
> >
>
>  Try this. I don't guarantee robustness.
>
>   str.scan(/\b.{0,50}(?:$|\b)/m)
Hmm my \b at the end of my solution might have been a problem in some
edge cases, however I would suggest the usage of \z instead of $ and
the m switch. I fail to see why you put a \b at the beginning David,
would you mind to explain?

In Ruby 1.9 (or Oniguruma that is) the negative lookahead assertion
might lead to the most elegant solution:

   /.{,50}(?!\B)/

BTW it seems that {n,m} does not have a "non greedy" and "possessive"
variant, or did I miss it?

Cheers
Robert