Masem is correct, use the reject keyword.

XXX: YYY
   | 'something' 'else'
   | 'a' <reject>
   | 'this string' <reject>
   | ZZZ <reject>

YYY: 'some string'
ZZZ: 'ww' | 'xx' | 'yy' | 'zz'

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This will cause the parse to fail for this branch, be careful that your grammar is not set up so that there are alternate paths to parse the string and your
$parser->start ($string);

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will fail.

"Don't you hate it when people quote themselves?" - me

In reply to Re: Parse::RecDescent - Any Way to do a Negation? by ajwans
in thread Parse::RecDescent - Any Way to do a Negation? by Incognito

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