color in perl

sub convert_token {
    my $self = shift;
    my $token = shift;

    return undef if !defined $token;
    return $token if length $token < 1;

    my $ttype = $self->terminal_type;
    return $token unless exists $color_map{$ttype}->{$token};
    return $color_map{$ttype}->{$token};
}

sub colorize {
    my $self = shift;
    my $msg = shift;

    return undef if !defined $msg;
    return $msg if length $msg < 1;

    my @bits = split /\%\^/, $msg;
    for (my $i = 0; $i < scalar @bits; $i++) {
        next if !defined $bits[$i];
        next if $bits[$i] eq '';
        $bits[$i] = $self->convert_token( $bits[$i] );
    }
    return join '', @bits;
}