public CacheItem<K, V> deleteTail() {
if (head.next == null) return null;
CacheItem<K, V> ret = tail;
tail = tail.prev;
tail.next = null;
ret.prev = null;
ret.next = null;
return ret;
}
public CacheItem<K, V> deleteHead() {
if (head.next == null) return null;
if (head.next == tail) {
tail = tail.prev;
}
CacheItem<K, V> ret = head.next;
head.next = ret.next;
if (ret.next != null) {
ret.next.prev = head;
}
ret.next = null;
ret.prev = null;
return ret;
}
public void delete(CacheItem<K, V> node) {
if (head.next == null) return;
if (node == head.next) {
deleteHead();
} else if (node == tail) {
deleteTail();
} else {
node.prev.next = node.next;
node.next.prev = node.prev;
node.next = null;
node.prev = null;
}
}
public void insertTail(CacheItem<K, V> node) {
tail.next = node;
node.prev = tail;
node.next = null;
tail = node;
}