def insertAtHead(self, item):
'''
pre: an item to be inserted into list
post: item is inserted into beginning of list
'''
node = ListNode(item)
if not self.length:
# set the cursor to the head because it's the
# first item inserted into the list
self.head = node
elif self.length == 1 and not self.tail:
self.tail = self.head
node.link = self.tail
self.head = node
else:
node.link = self.head
self.head = node
# set the cursor to the head if it's not set yet
if not self.cursor:
self.cursor = self.head
self.length += 1
def insertAtHead(self, item):
'''post: item is inserted at beginning of the list (before the
current head)'''
newNode = ListNode(item)
if self.head is None:
self.head = newNode
self.cursor = newNode
self.tail = newNode
self.length = 1
else:
newNode.link = self.head
self.head = newNode
self.length += 1
def insertAfterCursor(self, item):
'post: item is inserted after the cursor position'
newNode = ListNode(item)
if self.cursor is None:
self.head = newNode
self.cursor = newNode
self.tail = newNode
elif self.cursor is self.tail:
self.cursor.link = newNode
self.tail = newNode
else:
newNode.link = self.cursor.link
self.cursor.link = newNode
self.length += 1
