I'm not much in favor of regexes to solve problems like this in one swell foop. So long as the number of elements is sane, I'd build a hash and check for existence of a key. A regex is used to recognise ranged data and parse the boundary elements: 

#!/usr/bin/perl

my $set = [qw/A000 A123-A456 A999-B000 B789-B888/];
my %elements;

for (@$set) {
    /-/ or $elements{$_} = undef or next;
    if ( /([[:alpha:]]\d{3})-([[:alpha:]]\d{3})/ ) {
        my $start = $1;
        do { $elements{$start} = undef }
            while $start++ ne $2;
    }
}

while (<DATA>) {
    chomp;
    print "$_ is ",
          (exists $elements{$_} ? '' : 'not '),
          'in the set.',
          $/;
}

__DATA__
A000
A001
A122
A123
A124
A154
A320
A455
A456
A457
A530
A779
A932
A998
A999
B000
B001
B123
B666
B788
B789
B790
B820
B887
B888
B889
B900

[download]
That's a typical trade of memory for speed. The loop populating the %elements hash makes use of magical string increment to roll A over to B.

I should call attention to the difference between 

do { $elements{$start} = undef } while $start++ ne $2;
and 
$elements{$start} = undef while $start++ ne $2;
The latter will test and increment $start before any processing is done, while the do {} while cond; construction does the first pass unconditionally.

There is also a tricky bit of logic in the single element handling. . . . or next; is used to go to the next iteration unconditionally because the preceeding expression is always false.

After Compline,
Zaxo

In reply to Re: Need Set-like Regex for Perl and Java (golf OK) by Zaxo
in thread Need Set-like Regex for Perl and Java (golf OK) by QM

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