def insert(self, index, value):
"""Insert item by index.
Args:
index (int): index for insert
value : value for insert
Raises:
CollectionIsEmptyExeption: if list is empty
IndexError: if index is not valid
"""
if self.is_empty:
raise CollectionIsEmptyExeption(list_is_empty())
if not self.index_valid(index):
raise IndexError(index_out_of_range())
if index == 0:
self.push_front(value)
return
else:
node = Node(value)
previously = self._find_by(index - 1)
node.next = previously.next
previously.next = node
self._size += 1
def front(self):
"""Return (not extract) first item from list.
Returns:
item: first item from list
Raises:
CollectionIsEmptyExeption: if list is empty
"""
if self.is_empty:
raise CollectionIsEmptyExeption(list_is_empty())
return self._head.data
def pop_back(self):
"""Return (and extract) last item from list.
Returns:
last_item: last item from list
Raises:
CollectionIsEmptyExeption: if list is empty
"""
if self.is_empty:
raise CollectionIsEmptyExeption(list_is_empty())
penultimate = self._find_by(self._size - 2)
last = penultimate.next
penultimate.next = None
self._size -= 1
return last.data
def pop_front(self):
"""Return (and extract) first item from list.
Returns:
first_element_data: first item from list
Raises:
CollectionIsEmptyExeption: if list is empty
"""
if self.is_empty:
raise CollectionIsEmptyExeption(list_is_empty())
return_value = self._head.data
self._head = self._head.next
self._size -= 1
return return_value
def value_at(self, index):
"""Return (not extract) item by index.
Returns:
item: item from list by index
Args:
index (int): index return item
Raises:
CollectionIsEmptyExeption: if list is empty
IndexError: if index is not valid
"""
if self.is_empty:
raise CollectionIsEmptyExeption(list_is_empty())
if not self.index_valid(index):
raise IndexError(index_out_of_range())
finded = self._find_by(index)
return finded.data
def test_back_from_empty():
list = LinkedList()
with pytest.raises(CollectionIsEmptyExeption) as exception_info:
value = list.back
assert str(exception_info.value) == list_is_empty()
def test_pop_front_negative(value_at_fixture):
list = LinkedList()
with pytest.raises(CollectionIsEmptyExeption) as exception_info:
value = list.pop_back()
assert str(exception_info.value) == list_is_empty()
def test_value_at_empty_list():
list = LinkedList()
with pytest.raises(CollectionIsEmptyExeption) as exception_info:
value = list.value_at(list.size)
assert str(exception_info.value) == list_is_empty()
