-sub _set_parent ($$) {
- my ($id_table, $this) = @_;
-
- # B. For each element in the message's References field:
- defined(my $refs = $this->{references}) or return;
-
- # This loop exists to help fill in gaps left from missing
- # messages. It is not needed in a perfect world where
- # everything is perfectly referenced, only the last ref
- # matters.
- my $prev;
- foreach my $ref ($refs =~ m/$MID_EXTRACT/go) {
- # Find a Container object for the given Message-ID
- my $cont = $id_table->{$ref} //=
- PublicInbox::SearchThread::Msg::ghost($ref);
-
- # Link the References field's Containers together in
- # the order implied by the References header
- #
- # * If they are already linked don't change the
- # existing links
- # * Do not add a link if adding that link would
- # introduce a loop...
- if ($prev &&
- !$cont->{parent} && # already linked
- !$cont->has_descendent($prev) # would loop
- ) {
- $prev->add_child($cont);
- }
- $prev = $cont;
- }
-
- # C. Set the parent of this message to be the last element in
- # References.
- if (defined $prev && !$this->has_descendent($prev)) { # would loop
- $prev->add_child($this);
- }