/**
* Moves the element to the back.
*
* <p>Could also be implemented as remove() and unpop(), but explicitely coding might be a bit
* faster.
*
* @param element the entry to move to the back.
*/
public synchronized void moveLast(final Entry element) {
if (element.getValid() && element.getNext() != null) {
Entry next = element.getNext();
Entry prev = element.getPrevious();
next.setPrevious(prev);
if (prev != null) {
prev.setNext(next);
} else {
first = next;
}
last.setNext(element);
element.setPrevious(last);
element.setNext(null);
last = element;
}
}
/**
* Moves the element in front.
*
* <p>Could also be implemented as remove() and push(), but explicitely coding might be a bit
* faster.
*
* @param element the entry to move in front.
*/
public synchronized void moveFirst(final Entry element) {
if (element.getValid() && element.getPrevious() != null) {
Entry prev = element.getPrevious();
Entry next = element.getNext();
prev.setNext(next);
if (next != null) {
next.setPrevious(prev);
} else {
last = prev;
}
first.setPrevious(element);
element.setNext(first);
element.setPrevious(null);
first = element;
}
}
/**
* Adds an object to the start of the list and returns the entry created for said object. The
* entry can later be reused for moving the entry.
*
* @param object the object to prepend to the start of the list.
* @return an entry for use when the object should be moved.
*/
public synchronized Entry push(final T object) {
Entry entry = new Entry(object);
if (size >= maxSize) {
entry.setReplaced(pop());
}
if (first == null) {
first = last = entry;
} else {
first.setPrevious(entry);
entry.setNext(first);
first = entry;
}
size++;
return entry;
}
/**
* Removes the last element of the list and returns its content.
*
* @return the content of the last element of the list.
*/
public synchronized T pop() {
T content = null;
if (last != null) {
Entry element = last;
last = last.getPrevious();
content = element.getContent();
if (last == null) {
first = null;
} else {
last.setNext(null);
}
size--;
element.invalidate();
}
return content;
}
/**
* Removes any element of the list and returns its content.
*
* @param element The element to remove
*/
public synchronized void remove(final Entry element) {
if (element == null || !element.getValid()) {
return;
}
Entry next = element.getNext();
Entry prev = element.getPrevious();
if (next != null) {
next.setPrevious(prev);
} else {
last = prev;
}
if (prev != null) {
prev.setNext(next);
} else {
first = next;
}
size--;
element.invalidate();
}