package LinkedListModule

/** Turns a class into a linked list where each instance knows it's previous
	and next member in the list */
public module LinkedListModule
	static thistype first = null
	static thistype last = null
	static int size = 0
	thistype prev
	thistype next

	construct()
		size++
		if size == 1
			first = this
			prev = null
		else
			prev = last
			last.next = this
			first.prev = this
		next = null
		last = this

	static function getFirst() returns thistype
		return first

	function getNext() returns thistype
		if next == null
			return first
		return next

	function getPrev() returns thistype
		if prev == null
			return last
		return prev

	function remove()
		size--
		if this != first
			prev.next = next
		else
			first = next
		if this != last
			next.prev = prev
		else
			last = prev

	ondestroy
		remove()

	/** An iterator which iterates over all instances of this class */
	static function iterator() returns Iterator
		return new Iterator(true)

	private static let staticItr = new Iterator(false)

	/** An iterator which iterates over all instances of this class */
	static function staticItr() returns Iterator
		return staticItr..reset()

	/** An iterator which iterates over all instances of this class in reverse */
	static function backIterator() returns BackIterator
		return new BackIterator(true)

	private static let staticBackItr = new BackIterator(false)

	/** An iterator which iterates over all instances of this class in reverse */
	static function staticBackItr() returns BackIterator
		return staticBackItr..reset()

	static class Iterator
		LinkedListModule.thistype current = first
		protected bool destroyOnClose

		construct(bool destroyOnClose)
			this.destroyOnClose = destroyOnClose

		function hasNext() returns boolean
			return current != null

		function next() returns LinkedListModule.thistype
			let res = current
			current = current.next
			return res

		function reset()
			current = first

		function close()
			if destroyOnClose
				destroy this

	static class BackIterator
		LinkedListModule.thistype current = last
		protected bool destroyOnClose

		construct(bool destroyOnClose)
			this.destroyOnClose = destroyOnClose

		function hasNext() returns boolean
			return current != null

		function next() returns LinkedListModule.thistype
			let res = current
			current = current.prev
			return res

		function reset()
			current = last

		function close()
			if destroyOnClose
				destroy this