linkedlist.py

from exceptions import Empty
class Linkedlist:
    class _Node:
        __slots__ = '_element', '_next'

        def __init__(self,element,next):
            self._element=element
            self._next=next

    def __init__(self):
        self._head = None
        self._tail = None
        self._size = 0
    def __len__(self):
        return self._size

    def is_empty(self):
       return self._size==0

    def add_first(self,e):
        newest=self._Node(e,None)
        if self.is_empty():
            self._head=newest
            self._tail=newest
        else:
            newest ._next=self._head
        self._head=newest
        self._size+=1

    def add_last(self,e):
        newest = self._Node(e,None)
        if self.is_empty():
            self._head = newest
            self._tail = newest
        else:
            self._tail._next = newest
        self._tail = newest
        self._size += 1

    def add_any(self,e,pos):
        newest = self._Node(e, None)
        thead = self._head
        i = 1
        while i < pos:
            thead = thead._next
            i += 1
        newest._next=thead._next
        thead._next=newest
        self._size += 1

    def remove_first(self):
        if self.is_empty():
            raise Empty('Linked List Empty')
        value = self._head._element
        self._head = self._head._next
        self._size -= 1
        if self.is_empty():
            self._tail = None
        return value

    def remove_last(self):
        if self.is_empty():
            raise Empty('Linked List Empty')
        thead = self._head
        i=0
        while i < len(self) - 2:
            thead =thead._next
            i+=1
        self._tail= thead
        thead =thead._next
        value =thead._element
        self._tail._next = None
        self._size -= 1
        return value

    def remove_any(self, pos):
        if self.is_empty():
            raise Empty('Linked List Empty')
        thead = self._head
        i = 1
        while i < pos-1:
            thead = thead._next
            i += 1
        value = thead._next._element
        thead._next = thead._next._next
        self._size -= 1
        return value

    def display(self):
        thead = self._head
        while thead:
            print(thead._element, end='-->')
            thead = thead._next
        print()

L = Linkedlist()
L.add_last(10)
L.add_last(20)
L.add_last(30)
L.add_last(40)
L.display()
print('Deteted: ',L.remove_first())
L.display()
L.add_first(70)
L.display()
print('Deteted: ',L.remove_last())
L.display()
L.add_any(100,2)
L.display()
L.remove_any(2)
L.display()