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package lampion.collections;
object DirX {
abstract class Dir {
def reverse : Dir;
}
object BEFORE extends Dir {
def reverse = AFTER;
}
object AFTER extends Dir {
def reverse = BEFORE;
}
}
import DirX._;
abstract class Linked {
type Node <: Node0;
abstract class Node0 {
self: Node =>
var next : Node = _;
var prev : Node = _;
def get(dir : Dir) = if (dir == BEFORE) prev; else next;
private def set(dir : Dir, node : Node) =
if (dir == BEFORE) prev = node; else next = node;
def link(dir : Dir, node : Node) = {
assert(get(dir) == null);
assert(node.get(dir.reverse) == null);
set(dir, node);
node.set(dir.reverse, self);
}
def end(dir : Dir) : Node = {
if (get(dir) == null) this;
else get(dir).end(dir);
}
}
}
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