my @res_word = qw( ABOUT ACCUM AND BT BTG BTI BTP FUZZY HASPATH 
                   INPATH MINUS NEAR NOT NT NTG NTI NTP OR PT RT 
                   SQE SYN TR TRSYN TT WITHIN );
my @res_char = qw( , & ? { } \ ( ) [ ] - ; ~ | $ ! > * % _ );
my $rw = join '|', @res_word;
$rw = qr/$rw/;
my $rc = join '', map{"\\$_"}@res_char;
$rc = qr/[$rc]/;

sub escape {
    my $str = shift;
    $str =~ s/($rc)/\\$1/g;  # reserved char escapes
    $str =~ s/($rw)/{$1}/g;  # reserved word escapes
    $str =~ s/(['"])/$1$1/g; # quote escapes
  return $str;
}