| Description: |
Usage: pat ABCABC finds any word that has three repeated characters twice in a row (such as "murmur" in my dictionary). pat XYYX finds words that are four-character palindromes, such as "deed". In the result, X and Y must be different.
So pat ABCDEFGHAB finds ten-letter words whose first two and last
two characters are identical, but the remaining letters are all distinct, such
as "thousandth" or "Englishmen".
To require literal characters, use
lowercase, as in pat fXXd, requiring an f, two identical letters, and a d,
such as "food" or "feed".
For grins, dumps the regex that the pattern has been
transformed into, so you can write your own, or see how much work you're avoiding
by using this program.
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"Fun for the entire family!"
|
-- Rolling Stone magazine (but not
about this program)
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#!/usr/bin/perl -w
use strict;
open WORDS, "/usr/dict/words" or die "no more words: $!";
for (@ARGV) {
my @avoid = do {
my @lits = /[a-z]/g;
@lits ? "[" . join("", @lits) . "]" : ()
};
my %template;
my $regex = "^";
for (split //) {
if (/[a-z]/) {
$regex .= "$_";
} elsif (/[A-Z]/) {
if (exists $template{$_}) {
$regex .= $template{$_};
} else {
my $id = 1 + keys %template;
if (@avoid) {
$regex .= "(?!" . join("|", @avoid) . ")";
}
$regex .= "(.)";
push @avoid, $template{$_} = "\\$id";
}
} else {
warn "ignoring $_";
}
}
$regex .= "\$";
print "$_ => $regex\n";
seek WORDS, 0, 0;
while (<WORDS>) {
next unless /$regex/i;
print;
}
}
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