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Re: Pattern matching when there are exception strings

by tomazos (Deacon)
on Sep 21, 2005 at 14:54 UTC ( [id://493818]=note: print w/replies, xml ) Need Help??


in reply to Pattern matching when there are exception strings

This is the combination of japhy's solution with mine reposted here for completeness:

my (@prefixs, @suffixs); for (@exclusions) { my ($p, $s) = split /ALPHA/, $_, 2; push @prefixs, $p; push @suffixs, $s; } $total_raw = "(?!" . # Negative Lookahead: Any exceptional ALPHA "(" . join ("|", # Form (a|b|c) out of exceptional ALPHAs map ( # Form each exceptional ALPHA i # Lookbehind for prefix i "(?<=\Q$prefixs[$_]\E)" . "ALPHA" . # Lookahead for suffix i "(?=\Q$suffixs[$_]\E)", # where i = 0 to number of exceptions (0..$#exclusions) ) ) . ")" . ")" . . # Then match an ALPHA normally. # (We have already looked ahead and # confirmed that it is not exceptional) "ALPHA"; $total_rx = qr/$total_raw/;

$total_rx will only match a non-exceptional ALPHA, without modifying the string your searching on, and it doesn't forget any weird cases. It is a thing of beauty. :)

Enjoy,

-Andrew.


Andrew Tomazos  |  andrew@tomazos.com  |  www.tomazos.com

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