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linkedlist.py
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linkedlist.py
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import random
from unittest import TestCase
def first_true(sequence, func):
for item in sequence:
if func(item):
return item
return None
def last_node(index, node):
return node is None
def first_node(index, node):
return index == 0
class ListNode():
def __init__(self, value, prev_node=None, next_node=None):
self.value = value
self.previous = prev_node
self.next = next_node
def __repr__(self):
return "%s" % self.value
class DoubleLinkedList():
def __init__(self):
self._first = None
self._last = None
self._size = 0
def extend(self, values):
map(self.add, values)
def add(self, value, where=last_node):
if where is last_node:
self.__add_last(value)
return
if where is first_node:
self.__add_first(value)
return
for index, node in enumerate(self.__iter_nodes()):
if where(index, node):
self.__add_before(node, value)
return
self.__add_last(value)
def __add_first(self, value):
prev_first = self._first
self._first = ListNode(value, next_node=prev_first)
if prev_first is None:
self._last = self._first
else:
prev_first.previous = self._first
self._size += 1
def __add_last(self, value):
prev_last = self._last
self._last = ListNode(value, prev_node=prev_last)
if prev_last is None:
self._first = self._last
else:
prev_last.next = self._last
self._size += 1
def __add_before(self, node, value):
if node is self._first:
self._first = ListNode(value, next_node=self._first)
node.previous = self._first
else:
new_node = ListNode(value, prev_node=node.previous, next_node=node)
node.previous.next = new_node
node.previous = new_node
self._size += 1
def add_in(self, index, value):
node = self.__get_node(index)
self.__add_before(node, value)
def delete(self, value):
node = self.__search_node_with(value)
self.__delete_node(node)
def __delete_node(self, node):
if not node:
return False
def _del():
if len(self) == 1:
self._first = self._last = None
return
if node is self._first:
self._first = node.next
node.next.previous = None
return
if node is self._last:
self._last = node.previous
node.previous.next = None
return
node.next.previous = node.previous
node.previous.next = node.next
return
_del()
self._size -= 1
def min(self):
return min(self)
def max(self):
return max(self)
def __contains__(self, value):
return self.__search_node_with(value) is not None
def __len__(self):
return self._size
def __iter_nodes(self):
node = self._first
while node:
yield node
node = node.next
def __iter__(self):
return (node.value for node in self.__iter_nodes())
def __get_node(self, index):
self.__check_index(index)
forward = index < (len(self) >> 1)
if not forward:
index = len(self) - index - 1
node = self._first if forward else self._last
for _ in range(index):
node = getattr(node, "next" if forward else "previous")
return node
def __search_node_with(self, value):
return first_true(self.__iter_nodes(), lambda n: n.value == value)
def __check_index(self, index):
if index < 0 or index >= len(self):
raise IndexError()
def __getitem__(self, index):
node = self.__get_node(index)
return node.value
def __setitem__(self, index, value):
node = self.__get_node(index)
node.value = value
def __delitem__(self, index):
node = self.__get_node(index)
self.__delete_node(node)
def __repr__(self):
return "%s: %s" % (self.__class__.__name__, " -> ".join((str(n) for n in self)))
class DoubleLinkedListTestCase(TestCase):
@classmethod
def setUpClass(cls):
cls.BIG_LIST = DoubleLinkedList()
cls.MAX_ELEMENTS = 1000000
elements = range(cls.MAX_ELEMENTS)
random.shuffle(elements)
cls.BIG_LIST.extend(elements)
def __assert_order(self, elements):
ll = DoubleLinkedList()
ll.extend(elements)
print ll
self.assertEquals(len(ll), len(elements))
self.assertEquals([item for item in ll], elements)
def test1(self):
self.__assert_order([5,3,8,9,10,11,0])
def test2(self):
self.__assert_order([5,5,0,3,5,8,6,10])
def test3(self):
self.__assert_order([])
def test4(self):
self.__assert_order([1])
def test5(self):
self.__assert_order(range(10000)[::-1])
def test_add_10000_random(self):
elements = range(10000)
random.shuffle(elements)
self.__assert_order(elements)
def test7(self):
self.__assert_order([0,1,-1,-3,-5,9,-2])
def test8(self):
self.__assert_order([6, 5, 1, 9, 2, 4, 3, 8, 7, 0])
def test_max(self):
self.assertEquals(self.BIG_LIST.max(), self.MAX_ELEMENTS - 1)
def test_min(self):
self.assertEquals(self.BIG_LIST.min(), 0)
def test13(self):
ll = DoubleLinkedList()
ll.extend([5,5,0,3,5,8,6,10])
self.assertTrue(3 in ll)
ll.delete(3)
self.assertFalse(3 in ll)
self.assertEquals([item for item in ll], [5,5,0,5,8,6,10])
self.assertTrue(5 in ll)
ll.delete(5)
self.assertTrue(5 in ll)
ll.delete(5)
ll.delete(5)
self.assertFalse(5 in ll)
self.assertEquals([item for item in ll], [0,8,6,10])
self.assertTrue(0 in ll)
ll.delete(0)
self.assertFalse(0 in ll)
self.assertEquals([item for item in ll], [8,6,10])
self.assertTrue(8 in ll)
ll.delete(8)
self.assertFalse(8 in ll)
self.assertEquals([item for item in ll], [6,10])
self.assertTrue(6 in ll)
ll.delete(6)
self.assertFalse(6 in ll)
self.assertEquals([item for item in ll], [10])
self.assertTrue(10 in ll)
ll.delete(10)
self.assertFalse(10 in ll)
self.assertEquals([item for item in ll], [])
self.assertEquals(len(ll), 0)
def test14(self):
ll = DoubleLinkedList()
ll.add(1)
self.assertEquals(len(ll), 1)
self.assertTrue(1 in ll)
ll.delete(1)
self.assertFalse(1 in ll)
ll.add(2)
ll.add(3)
self.assertEquals(len(ll), 2)
def test15(self):
self.__assert_order(range(1000))
def test16(self):
ll = DoubleLinkedList()
ll.extend([5,5,0,3,5,8,6,10])
self.assertEquals(ll[1], 5)
self.assertEquals(ll[2], 0)
self.assertRaises(IndexError, ll.__getitem__, 8)
def test_get_from_10000(self):
ll = DoubleLinkedList()
ll.extend(range(10000))
self.assertEquals(ll[1], 1)
self.assertEquals(ll[9998], 9998)
def test_setitem(self):
ll = DoubleLinkedList()
ll.extend(range(100))
self.assertEquals(ll[1], 1)
ll[1] = 5
self.assertEquals(ll[1], 5)
self.assertRaises(IndexError, ll.__setitem__, 101, 1)
def test_add_in_index(self):
ll = DoubleLinkedList()
ll.extend(range(10))
self.assertEquals(ll[1], 1)
self.assertEquals(ll[2], 2)
ll.add_in(1, 666)
self.assertEquals(ll[1], 666)
self.assertEquals(ll[2], 1)
self.assertEquals(ll[3], 2)