Doubly-linked list/Element insertion: Difference between revisions
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→{{header|Perl 6}}: Add referenced pieces from other tasks to make runnable example
(→{{header|Kotlin}}: Updated example see https://github.com/dkandalov/rosettacode-kotlin for details) |
Thundergnat (talk | contribs) m (→{{header|Perl 6}}: Add referenced pieces from other tasks to make runnable example) |
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=={{header|Perl 6}}==
Using the generic definitions from [[Doubly-linked_list/Definition#Perl_6]]:
<lang perl6>
has DLElem[T] $.prev is rw;
has DLElem[T] $.next is rw;
has T $.payload = T;
method pre-insert(T $payload) {
die "Can't insert before beginning" unless $!prev;
my $elem = ::?CLASS.new(:$payload);
$!prev.next = $elem;
$elem.prev = $!prev;
$elem.next = self;
$!prev = $elem;
$elem;
}
method post-insert(T $payload) {
die "Can't insert after end" unless $!next;
my $elem = ::?CLASS.new(:$payload);
$!next.prev = $elem;
$elem.next = $!next;
$elem.prev = self;
$!next = $elem;
$elem;
}
method delete {
die "Can't delete a sentinel" unless $!prev and $!next;
$!next.prev = $!prev;
$!prev.next = $!next; # conveniently returns next element
}
}
role DLList[::DLE] {
has DLE $.first;
has DLE $.last;
submethod BUILD {
$!first = DLE.new;
$!last = DLE.new;
$!first.next = $!last;
$!last.prev = $!first;
}
method list { ($!first.next, *.next ...^ !*.next).map: *.payload }
method reverse { ($!last.prev, *.prev ...^ !*.prev).map: *.payload }
}
class DLElem_Str does DLElem[Str] {}
class DLList_Str does DLList[DLElem_Str] {}
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