From: Logan Capaldo <logancapaldo@...>
Date: 2007-08-14T07:36:11+09:00
Subject: Re: Split a string based on change of character

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On 8/13/07, Brad Phelan <phelan@tttech.ttt> wrote:
>
> Andrew Savige wrote:
> > For a string "ZBBBCZZ", I want to produce a list ["Z", "BBB", "C", "ZZ"]
> > That is, break the string into pieces based on change of character.
> >
> > Though this works:
> >
> >   s = "ZBBBCZZ"
> >   x = s.scan(/((.)\2*)/).map {|i| i[0]}
>
> Another variant which gets rid of one of the capture
> groups and does introduce an artificial split character
>
> Enumerator.new(s, :scan, /(.)\1*/).map {$&}
>
> Note the $& will not work in the example
>
> >   x = s.scan(/((.)\2*)/).map {|i| i[0]}
>
> because the map is run on an array after the
> scan has happened. To run the map inline with
> the scan you need the Enumerator object.
>
> I doubt using Enumerator is any faster though.
>
> Wouldn't it be nicer if scan returned an
> enumerable instead of an array. We could
> define
>
> class String
>     def scan_enum regexp
>         Enumerator.new self, :scan, regexp
>     end
> end
>
> and then be able to do
>
> s.scan_enum(/(.)\1*/).map {$&}


What's wrong with s.enum_for(:scan, /(.)\1*/).map { $& } ?

--
> Brad Phelan
> http://xtargets.com
>
>

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