From: Eric Christopherson <echristopherson@...>
Date: 2013-01-31T12:26:27+09:00
Subject: Re: How backtracking works in Ruby?

On Fri, Jan 18, 2013 at 10:01 AM, Arup Rakshit <lists@ruby-forum.com> wrote:
> Hi,
>
>
> What i am going to ask is very basic thing I know. But,as a newbie to
> this platform,I am not getting the keen concept of backtracking in Regex
> of Ruby. In such a case can any one help me to understand the core of
> this concept by answering the following questions?
>
> (a) What is backtracking?
>
> (b) Why we need it?(means how regex with backtracking differs from a
> regex without backtracking?)
>
> (c) How it works when it is being used with any Regex? (It would be
> great if it can be visualized with some code snippets to understand how
> does it work)
>
> (d) In what situation we have to think of it to use?
>
>
> I used the link( http://ruby-doc.org/core-1.9.3/Regexp.html ) to get
> it's core,but my bad i am not getting the answers of all my above
> questions from here to have the concept.

This freely-available chapter from _Mastering regular expressions_
talks about backtracking, although it doesn't mention Ruby
specifically: http://oreilly.com/catalog/regex/chapter/ch04.html