#! perl -slw
use strict;

for( qw[
    ab123
    'ab123s
    'ab123's
] ) {
    if(
        m[
            ^'? [a-z]               ## start with letter or an apostrophy followed by one
            [a-z0-9'-_]+            ## Alphanumeric + '-_
            (?: [a-z0-9] | s') $    ## ends with alphanumeric or s'
        ]x
        and not
        m[''|--]                    ## No doubled ''s or --s
    ){
        print "$_: Ok!";
    } else {
        print "$_: Bad!";
    }
}
__END__
C:\test>junk
ab123: Ok!
'ab123s: Ok!
'ab123's: Ok!