| 4 | pass |
| 5 | |
| 6 | class LinkedDeque(_DoublyLinkedList): |
| 7 | |
| 8 | def first(self): |
| 9 | if self.is_empty(): |
| 10 | raise Empty("Dequeu is empty") |
| 11 | return self._header._next._element |
| 12 | |
| 13 | def last(self): |
| 14 | if self.is_empty(): |
| 15 | raise Empty("Dequeu is empty") |
| 16 | return self._trailer._previous._element |
| 17 | |
| 18 | def insert_first(self, element): |
| 19 | self._insert_between(element, self._header, self._trailer) |
| 20 | |
| 21 | def insert_last(self, element): |
| 22 | self._insert_between(element, self._trailer._previous, self._trailer) |
| 23 | |
| 24 | def delete_first(self): |
| 25 | if self.is_empty(): |
| 26 | raise Empty("Deque is empty") |
| 27 | return self._delete_node(self._header._next) |
| 28 | |
| 29 | def delete_last(self): |
| 30 | if self.is_empty(): |
| 31 | raise Empty("Deque is empty") |
| 32 | |
| 33 | return self._delete_node(self._trailer._previous) |
| 34 | |