def test_DoublyLinkedList___repr__(self):
l1 = DoublyLinkedList()
l1.insert(0)
l1.insert(1)
l1.insert(2)
self.assertEquals(l1.__repr__(), "(2, 1, 0)")
class RingBuffer:
def __init__(self, capacity):
self.capacity = capacity
self.current = None # what's going to be overwritten
self.storage = DoublyLinkedList()
def __repr__(self):
return self.storage.__repr__()
def append(self, item):
# if empty, set the current to the head
if self.storage.length == 0:
self.storage.add_to_tail(item)
self.current = self.storage.head
# if less than capcacity, link the tail to head after adding
elif self.storage.length < self.capacity:
self.storage.add_to_tail(item)
self.storage.tail.next = self.storage.head
# otherwise, overwrite the oldest, and move the oldest to next item
# since tail is linked to head, this works fine
else:
self.current.value = item
self.current = self.current.next
def get(self):
# Note: This is the only [] allowed
list_buffer_contents = []
current = self.storage.head
while current is not self.storage.tail:
list_buffer_contents.append(current.value)
current = current.next
list_buffer_contents.append(self.storage.tail.value)
return list_buffer_contents
class Stack:
def __init__(self):
self.size = 0
# Why is our DLL a good choice to store our elements?
# a lot of insertion at the head and then
self.storage = DoublyLinkedList()
def __repr__(self):
return self.storage.__repr__()
def push(self, value):
self.size += 1
return self.storage.add_to_tail(value)
def pop(self):
self.size -= 1
return self.storage.remove_from_tail()
def len(self):
return self.storage.length
