#! perl -slw
use strict;

my $input = 'A000,A123-A456,A999-B000,B789-B888';
my $set = join'', map{ 
	m[ ( [A-Z] \d{3} ) (?:- ( [A-Z] \d{3} ) )?]x;
	$1 .. $2||$1
} split ',', $input;

for my $testVal ( 'A100', 'A234', 'B000', 
                  'B789 does match', 'B788 but not this' ){
      ## The test
	if( $testVal =~ m[([A-Z]\d{3})] and 1+index( $set, $1 ) ) {

		print "'$testVal' contains a match for '$input'";
	}
	else {
		print "No match for '$testVal'";
	}
}

__END__
P:\test>362578
No match for 'A100'
'A234' contains a match for 'A000,A123-A456,A999-B000,B789-B888'
'B000' contains a match for 'A000,A123-A456,A999-B000,B789-B888'
'B789 does match' contains a match for 'A000,A123-A456,A999-B000,B789-B888'
No match for 'B788 but not this'