Hi! A quick search on the CPAN and I found Tie::RegexpHash, which seems to suit your needs. I've never used it, but here's an example from the man page:

use Tie::RegexpHash;
my %hash;
tie %hash, 'Tie::RegexpHash';

$hash{ qr/^5(\s+|-)?gal(\.|lons?)?/i } = '5-GAL';

$hash{'5 gal'};     # returns "5-GAL"
$hash{'5GAL'};      # returns "5-GAL"
$hash{'5  gallon'}; # also returns "5-GAL"
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