DoublyLinkedList.py

#credit: joejames
class Node(object):

	def __init__ (self, d, n = None, p = None):
		self.data = d
		self.next_node = n
		self.prev_node = p

	def get_next (self):
		return self.next_node

	def set_next (self, n):
		self.next_node = n
		
	def get_prev (self):
		return self.prev_node

	def set_prev (self, p):
		self.prev_node = p
		
	def get_data (self):
		return self.data

	def set_data (self, d):
		self.data = d
		
	def to_string (self):
		return "Node value: " + str(self.data)
		
	def has_next (self):
		if self.get_next() is None:
			return False
		return True

class DoublyLinkedList (object):

	def __init__ (self, r = None):
		self.root = r
		self.last = r
		self.size = 0

	def get_size (self):
		return self.size

	def add (self, d):
		if self.size == 0:
			self.root = Node(d)
			self.last = self.root
		else:
			new_node = Node(d, self.root)
			self.root.set_prev(new_node)
			self.root = new_node
		self.size += 1

	def remove (self, d):
		this_node = self.root
		while this_node is not None:
			if this_node.get_data() == d:
				if this_node.get_prev() is not None:
					if this_node.has_next():	# delete a middle node
						this_node.get_prev().set_next(this_node.get_next())
						this_node.get_next().set_prev(this_node.get_prev())
					else:	# delete last node
						this_node.get_prev().set_next(None)
						self.last = this_node.get_prev()
				else: # delete root node
					self.root = this_node.get_next()
					this_node.get_next().set_prev(self.root)
				self.size -= 1
				return True     # data removed
			else:
				this_node = this_node.get_next()
		return False  # data not found

	def find (self, d):
		this_node = self.root
		while this_node is not None:
			if this_node.get_data() == d:
				return d
			elif this_node.get_next() == self.root:
				return False
			else:
				this_node = this_node.get_next()
	
	def print_list (self):
		print ("Print List..........")
		if self.root is None:
			return
		this_node = self.root
		print (this_node.to_string())
		while this_node.has_next():
			this_node = this_node.get_next()
			print (this_node.to_string())

def main():
	myList = DoublyLinkedList()
	myList.add(5)
	myList.add(9)
	myList.add(3)
	myList.add(8)
	myList.add(9)
	print("size="+str(myList.get_size()))
	myList.print_list()
	myList.remove(8)
	print("size="+str(myList.get_size()))
	print("Remove 15", myList.remove(15))
	myList.add(21)
	myList.add(22)
	myList.remove(5)
	myList.print_list()
	print("size="+str(myList.get_size()))
	print(myList.last.get_prev().to_string())

main()