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Re: positive regex for inverted match

by kvale (Monsignor)
on Feb 26, 2004 at 06:33 UTC ( [id://331921]=note: print w/replies, xml ) Need Help??


in reply to positive regex for inverted match

Here is a regex solution to you problem: 
while (<DATA>) {
   chomp;
   print "$_ has no bar\n" if /^([^b]|b[^a]|ba[^r])+$/;
}

__DATA__
bar
foo
"bar" blah
baz "bar" blah
"test" blah
"test2"

[download]

-Mark

Replies are listed 'Best First'.
Re^2: positive regex for inverted match (classic)
by tye (Sage) on Feb 26, 2004 at 07:55 UTC

    Classic++, including classic mistakes. (:

    Your regex will match "bbar" despite it containing "bar". "bb" matches b[^a] and then "a" and "r" each match [^b].

    I started exploring this idea in depth and hope to write a lengthy node on it one day. Trying to fix the problems leads you down paths similar to: 

    /^([^b]|b[^a]| ba[^r])+$/
/^([^b]+|b+[^ab]| b+a[^rb])*b*a?$/
/^([^b]+|b+[^ab]|(b+a)+([^rb]|b+[^ab]))*[ba]*$/

    [download]

    - tye        

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