my $bool_func = "((S0*B)|((!S0)*A))";
(my $perl_expr = $bool_func) =~ s/([a-zA-Z]\w*)/\$val{$1}/g;

print "Using perl expression: $perl_expr\n";

my @vars = do {
    my %seen;
    grep !$seen{$_}++, $bool_func =~ /([a-zA-Z]\w*)/g;
};

for my $assignment ( 0 .. (2**@vars)-1 ) {
    my %val;

    $val{$vars[$_]} = ( $assignment >> $_ ) & 1
        for 0 .. $#vars;

    my $result = eval $perl_expr;

    print join(", ", map { "$_=$val{$_}" } keys %val),
          " ==> $bool_func=$result\n";
}

__END__
Using perl expression: (($val{S0}*$val{B})|((!$val{S0})*$val{A}))
A=0, S0=0, B=0 ==> ((S0*B)|((!S0)*A))=0
A=0, S0=1, B=0 ==> ((S0*B)|((!S0)*A))=0
A=0, S0=0, B=1 ==> ((S0*B)|((!S0)*A))=0
A=0, S0=1, B=1 ==> ((S0*B)|((!S0)*A))=1
A=1, S0=0, B=0 ==> ((S0*B)|((!S0)*A))=1
A=1, S0=1, B=0 ==> ((S0*B)|((!S0)*A))=0
A=1, S0=0, B=1 ==> ((S0*B)|((!S0)*A))=1
A=1, S0=1, B=1 ==> ((S0*B)|((!S0)*A))=1