From: Rick DeNatale <rick.denatale@...>
Date: 2007-03-13T01:25:14+09:00
Subject: Re: Efficiency of string parsing

On 3/12/07, Robert Klemme <shortcutter@googlemail.com> wrote:

> There are quite a lot of posts about word wrapping which seems what you
> are trying to do.  You should be able to find them via the archives
> (Google Groups, ruby-talk archive).
>
> A simplistic approach would probably do something like this:
>
> str.gsub(/(.{1,50})\s+/, "\\1\n")
>

And here's the start of a more sophisticated approach I just whipped up.

It uses split on a word boundary to split the string. It has some
option keywords which allow preserving all whitespace, or only at the
beginning of a line.  If you don't preserve all whitespace, it
collapses whitespace within a line to a single space.  If you don't
preserve whitespace at the beginning of a line, it elminates it,
otherwise it keeps it as is.  The default is to only preserve
whitespace at the beginning of a line.

It does have a few bugs, which I didn't bother addressing and leave as
an exercise ot the reader.

1) It ignores existing new lines in the input string, which means that
the next line will be short.

2) It keeps whitespace at the end of a line, as opposed to putting the
newline after the last 'word'.

class String
  def wordwrap(linelength, kw_args={})
    keep_all = kw_args[:keep_all]
    keep_initial = keep_all ||kw_args[:keep_initial]
    keep_initial = true if keep_initial.nil?
    current_len = 0
    split(/\b/).inject("") do | result, chunk |
      if current_len + chunk.length >= linelength
        result << "\n"
	current_len = 0
        chunk = "" if chunk.strip.empty? unless keep_initial
      else
	chunk = " " if chunk.strip.empty? unless keep_all
      end
      current_len += chunk.length
      result << chunk
    end
  end
end
-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/