# should be ok for any version 5.8.9+
sub replace_5_8_9_b {

    my ($string,
        ) = @_;

    my $rx_dquot  = qr{ " [^"]* (?: "" [^"]* )* " }xms;
    my $rx_ceol   = qr{ ' [^\n]* \n? \z           }xms;
    my $rx_skipem = qr{ $rx_ceol | $rx_dquot }xms;  # alt order immaterial
  # my $rx_skipem = qr{ $rx_dquot | $rx_ceol }xms;  # alt order immaterial
    my $rx_keepit = qr{ (?! $rx_rename) (?! $rx_dquot) (?! $rx_ceol) . }xms;

    $string =~ s{
        \G
        ((?: (?> $rx_keepit*) | (?> $rx_skipem*))*)  # skip this stuff
        ($rx_rename)                                 # grab and rename
        }
        {$1$renames->{$2}}xmsg;

    return $string;

    }

# uses \K and possessive quantifiers from 5.10+
sub replace_5_10_1_b {

    my ($string,
        ) = @_;

    my $rx_dquot  = qr{ " [^"]*+ (?: "" [^"]*+ )*+ " }xms;
    my $rx_ceol   = qr{ ' [^\n]*+ \n?+ \z            }xms;
    my $rx_skipem = qr{ $rx_ceol | $rx_dquot }xms;  # alt order immaterial
  # my $rx_skipem = qr{ $rx_dquot | $rx_ceol }xms;  # alt order immaterial
    my $rx_keepit = qr{ (?! $rx_rename) (?! $rx_dquot) (?! $rx_ceol) . }xms;

    $string =~ s{
        \G
        (?: $rx_keepit*+ | $rx_skipem*+)*  # skip this stuff
        \K
        ($rx_rename)                       # grab and rename
        }
        {$renames->{$1}}xmsg;

    return $string;

    }