From: Andrew Stewart <boss@...>
Date: 2008-01-17T20:51:37+09:00
Subject: Re: regular expression


On 16 Jan 2008, at 22:19, Wolfgang Nádasi-Donner wrote:
> Andrew Stewart wrote:
>> You can see there's a lot of repetition in the regular expression so
>> the next step would probably be to DRY it.
>
> O.K. - it really increases the readability ;-)
>
> re = Regexp.compile((v=p='')+"^#{p="[^#{v='aeiou'}]*"}"+v.split('').
>      join("[^#{v}]*")+p+'$')
> p re # =>
> /^[^aeiou]*a[^aeiou]*e[^aeiou]*i[^aeiou]*o[^aeiou]*u[^aeiou]*$/

Yikes!

That's clever though my brain copes better with this halfway house:

   consonant = /[^aeiou]/
   re = /#{consonant}*a#{consonant}*e#{consonant}*i#{consonant}*o# 
{consonant}*u#{consonant}*/

Or, perhaps, in-between the in-betweens:

   vowels = %w( a e i o u )
   consonant = '[^aeiou]'
   re = /#{vowels.push('').unshift('').join("#{consonant}*")}/

Regards,
Andy Stewart

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