From: Robert Klemme <shortcutter@...>
Date: 2009-11-27T16:15:10+09:00
Subject: Re: Pattern match to fail if two periods in a row

On 11/26/2009 09:46 PM, Ralph Shnelvar wrote:
>>>> "abc..def" !~ /\.\./
> =>> false
> 
> I don't think that
>   "abc..def" !~ /\.\./
> is a regular expression.
> 
>    /\.\./
> is a regular expression.
> 
> 
> Basically ... I need something that will work in a Rails validates_format_of
> 
>   # Reject if the email address has two periods in a row
>   validates_format_of     :email,
>                         # See http://en.wikipedia.org/wiki/E-mail_address
>                         :with => ????,
>                         :message => 'invalid email format'

You could try negative lookahead

irb(main):001:0> s=["aaa", "a.", ".a", "a..", "..a"]
=> ["aaa", "a.", ".a", "a..", "..a"]
irb(main):002:0> s.map {|x| [x, /\A(?:.(?!\.\.))*\z/ =~ x]}
=> [["aaa", 0], ["a.", 0], [".a", 0], ["a..", nil], ["..a", 0]]

Or maybe there is an ":without" which uses the negated match?

Kind regards

	robert

-- 
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