def insert_at(self, index, key, data=None):
if self.size == 0 and (index in (0, -1)):
index = 0
if index < 0:
index = self.size + index
if index > self.size:
raise IndexError('%d index is out of range.' % (index))
self.size += 1
new_node = LinkedListNode(key, data, links=['next'], addrs=[None])
if self.size == 1:
self.head, self.tail = \
new_node, new_node
elif index == self.size - 1:
new_node.next = self.tail.next
self.tail.next = new_node
self.tail = new_node
else:
counter = 0
current_node = self.head
prev_node = None
while counter != index:
prev_node = current_node
current_node = current_node.next
counter += 1
new_node.next = current_node
if prev_node is not None:
prev_node.next = new_node
if new_node.next is None:
self.tail = new_node
if index == 0:
self.head = new_node
def insert_after(self, prev_node, data):
"""
Inserts a new node after the prev_node.
Parameters
==========
prev_node: LinkedListNode
The node after which the
new node is to be inserted.
data
Any valid data to be stored in the node.
"""
self.size += 1
new_node = LinkedListNode(data,
links=['next', 'prev'],
addrs=[None, None])
new_node.next = prev_node.next
if new_node.next is not None:
new_node.next.prev = new_node
prev_node.next = new_node
new_node.prev = prev_node
if new_node.next is None:
self.tail = new_node
def insert_before(self, next_node, data):
"""
Inserts a new node before the next_node.
Parameters
==========
next_node: LinkedListNode
The node before which the
new node is to be inserted.
data
Any valid data to be stored in the node.
"""
self.size += 1
new_node = LinkedListNode(data,
links=['next', 'prev'],
addrs=[None, None])
new_node.prev = next_node.prev
next_node.prev = new_node
new_node.next = next_node
if new_node.prev is not None:
new_node.prev.next = new_node
else:
self.head = new_node
def insert_after(self, prev_node, key, data=None):
self.size += 1
new_node = LinkedListNode(key, data, links=['next'], addrs=[None])
new_node.next = prev_node.next
prev_node.next = new_node
if new_node.next is None:
self.tail = new_node
def insert_before(self, next_node, key, data=None):
self.size += 1
new_node = LinkedListNode(key, data,
links=['next', 'prev'],
addrs=[None, None])
new_node.prev = next_node.prev
next_node.prev = new_node
new_node.next = next_node
if new_node.prev is not None:
new_node.prev.next = new_node
else:
self.head = new_node
def insert_at(self, index, key, data=None):
"""
Inserts a new node at the input index.
Parameters
==========
index: int
An integer satisfying python indexing properties.
data
Any valid data to be stored in the node.
"""
if self.size == 0 and (index in (0, -1)):
index = 0
if index < 0:
index = self.size + index
if index > self.size:
raise IndexError('%d index is out of range.' % (index))
self.size += 1
new_node = LinkedListNode(key,
data,
links=['next', 'prev'],
addrs=[None, None])
if self.size == 1:
self.head, self.tail = \
new_node, new_node
else:
counter = 0
current_node = self.head
prev_node = None
while counter != index:
prev_node = current_node
current_node = current_node.next
counter += 1
new_node.prev = prev_node
new_node.next = current_node
if prev_node is not None:
prev_node.next = new_node
if current_node is not None:
current_node.prev = new_node
if new_node.next is None:
self.tail = new_node
if new_node.prev is None:
self.head = new_node
