auto
 ?÷     mple($u))
	if $uXS && _exists_simple($u);
### end XS only ###

    # JCPS must not be a contraction, then it's a code point.
    if (Hangul_SIni <= $u && $u <= Hangul_SFin) {
	my $hang = $self->{overrideHangul};
	my @hangulCE;
	if ($hang) {
	    @hangulCE = map _pack_override($_, $u, $der), $hang->($u);
	} elsif (!defined $hang) {
	    @hangulCE = $der->($u);
	} else {
	    my $max  = $self->{maxlength};
	    my @decH = _decompHangul($u);

	    if (@decH == 2) {
		my $contract = join(CODE_SEP, @decH);
		@decH = ($contract) if $map->{$contract};
	    } else { # must be <@decH == 3>
		if ($max->{$decH[0]}) {
		    my $contract = join(CODE_SEP, @decH);
		    if ($map->{$contract}) {
			@decH = ($contract);
		    } else {
			$contract = join(CODE_SEP, @decH[0,1]);
			$map->{$contract} and @decH = ($contract, $decH[2]);
		    }
		    # even if V's ignorable, LT contraction is not supported.
		    # If such a situation were required, NFD should be used.
		}
		if (@decH == 3 && $max->{$decH[1]}) {
		    my $contract = join(CODE_SEP, @decH[1,2]);
		    $map->{$contract} and @decH = ($decH[0], $contract);
		}
	    }

	    @hangulCE = map({
		    $map->{$_} ? @{ $map->{$_} } :
		$uXS && _exists_simple($_) ? _fetch_simple($_) : ### XS only
		    $der->($_);
		} @decH);
	}
	return map $self->varCE($_), @hangulCE;
    } else {
	my $cjk  = $self->{overrideCJK};
	my $vers = $self->{UCA_Version};
	if ($cjk && _isUIdeo($u, $vers)) {
	    my @cjkCE = map _pack_override($_, $u, $der), $cjk->($u);
	    return map $self->varCE($_), @cjkCE;
	}
	if ($vers == 8 && defined $cjk && _isUIdeo($u, 0)) {
	    return map $self->varCE($_), _uideoCE_8($u);
	}
	return map $self->varCE($_), $der->($u);
    }
}


##
## string sortkey = getSortKey(string arg)
##
sub getSortKey
{
    my $self = shift;
    my $rEnt = $self->splitEnt(shift); # get an arrayref of JCPS
    my $vers = $self->{UCA_Version};
    my $term = $self->{hangul_terminator};

    my @buf; # weight arrays
    if ($term) {
	my $preHST = '';
	my $termCE = $self->varCE(pack(VCE_TEMPLATE, NON_VAR, $term, 0,0,0));
	foreach my $jcps (@$rEnt) {
	    # weird things like VL, TL-contraction are not considered!
	    my $curHST = join '', map getHST($_, $vers), split /;/, $jcps;
	    if ($preHST && !$curHST || # hangul before non-hangul
		$preHST =~ /L\z/ && $curHST =~ /^T/ ||
		$preHST =~ /V\z/ && $curHST =~ /^L/ ||
		$preHST =~ /T\z/ && $curHST =~ /^[LV]/) {
		push @buf, $termCE;
	    }
	    $preHST = $curHST;
	    push @buf, $self->getWt($jcps);
	}
	push @buf, $termCE if $preHST; # end at hangul
    } else {
	foreach my $jcps (@$rEnt) {
	    push @buf, $self->getWt($jcps);
	}
    }

    return $self->mk_SortKey(\@buf); ### XS only
}


##
## int compare = cmp(string a, string b)
##
sub cmp { $_[0]->getSortKey($_[1]) cmp $_[0]->getSortKey($_[2]) }
sub eq  { $_[0]->getSortKey($_[1]) eq  $_[0]->getSortKey($_[2]) }
sub ne  { $_[0]->getSortKey($_[1]) ne  $_[0]->getSortKey($_[2]) }
sub lt  { $_[0]->getSortKey($_[1]) lt  $_[0]->getSortKey($_[2]) }
sub le  { $_[0]->getSortKey($_[1]) le  $_[0]->getSortKey($_[2]) }
sub gt  { $_[0]->getSortKey($_[1]) gt  $_[0]->getSortKey($_[2]) }
sub ge  { $_[0]->getSortKey($_[1]) ge  $_[0]->getSortKey($_[2]) }

##
## list[strings] sorted = sort(list[strings] arg)
##
sub sort {
    my $obj = shift;
    return
	map { $_->[1] }
	    sort{ $a->[0] cmp $b->[0] }
		map [ $obj->getSortKey($_), $_ ], @_;
}


##
## bool _nonIgnorAtLevel(arrayref weights, int level)
##
sub _nonIgnorAtLevel($$)
{
    my $wt = shift;
    return if ! defined $wt;
    my $lv = shift;
    return grep($wt->[$_-1] != 0, MinLevel..$lv) ? TRUE : FALSE;
}

##
## bool _eqArray(
##    arrayref of arrayref[weights] source,
##    arrayref of arrayref[weights] substr,
##    int level)
## * comparison of graphemes vs graphemes.
##   @$source >= @$substr must be true (check it before call this);
##
sub _eqArray($$$)
{
    my $source = shift;
    my $substr = shift;
    my $lev = shift;

    for my $g (0..@$substr-1){
	# Do the $g'th graphemes have the same number of AV weights?
	return if @{ $source->[$g]