double_linked_list.py

#!/bin/python3
# -*- coding:utf-8 -*-

import os

class DoubleLinkedList:
    class Node:
        def __init__(self, value):
            self.value = value
            self.prev : DoubleLinkedList.Node = None
            self.next : DoubleLinkedList.Node = None

        def get_prev_value(self):
            if self.prev == None:
                return None
            else:
                return self.prev.value
        
        def get_next_value(self):
            if self.next == None:
                return None
            else:
                return self.next.value

    def __init__(self):
        self.head : DoubleLinkedList.Node = None
        self.len = None

    def __iter__(self):
        node = self.head

        while node != None:
            yield node
            node = node.next

    def get_first(self):
        return self.head 

    def get_last(self):
        n = self.head

        while n != None and n.next != None:
            n = n.next

        return n

    def add_first(self, value):
        n = DoubleLinkedList.Node(value)

        if self.head == None:
            self.head = n
        else:
            n.next = self.head
            self.head.prev = n

            self.head = n

        return n

    def add_last(self, value):
        n = DoubleLinkedList.Node(value)

        if self.head == None:
            self.head = n
        else:
            node_last = self.get_last()
            node_last.next = n
            n.prev = node_last

        return n

    def add_after(self, node : Node, value):
        n = DoubleLinkedList.Node(value)

        if node.next != None:
            node.next.prev = n
            n.next = node.next

        node.next = n
        n.prev = node

        return n

    def add_before(self, node : Node, value):
        n = DoubleLinkedList.Node(value)

        if node.prev == None:
            n.next = node
            node.prev = n

            self.head = n
        else: 
            node.prev.next = n
            n.prev = node.prev

            node.prev = n
            n.next = node

        return n

    def clear(self):
        n = self.head

        while n.next != None:
            n.prev = None
            n.next = None
            n = node.next

    def remove(self, node : Node):
        if self.head == node:
            self.head = node.next

        if node.prev != None:
            node.prev.next = node.next
        if node.next != None:
            node.next.prev = node.prev

        node.prev = None
        node.next = None



    def remove_first(self):
        if self.head == None:
            return

        node = self.head.next
        if node != None:
            node.prev = None
            self.head = node
        else:
            self.head = None

    def remove_last(self):
        node = self.get_last()

        if node.prev != None:
            node.prev.next = None
            node.prev = None

        if node == self.head:
            self.head = None

    def find_node(self, value):
        n = self.head

        while n != None:
            if n.value == value:
                return n

            n = n.next
        
        return None


if __name__ == "__main__":
    lst = DoubleLinkedList()

    while True:
        os.system('cls')
        print("-------------------------------------------------------------------------------------")
        index = 0
        for node in lst:
            pad = ' ' * (index * 5)
            vp = node.get_prev_value()
            vn = node.get_next_value()
            vp = vp if vp != None else ""
            vn = vn if vn != None else ""
            print("%s< %2s | %2s | %2s >" % (pad, vp, node.value, vn))
            index += 1
        print("-------------------------------------------------------------------------------------")
        print("0 : exit")
        print("1 : add first")
        print("2 : add last")
        print("3 : add after")
        print("4 : add before")
        print("5 : remove first")
        print("6 : remove last")
        print("7 : remove")

        print("command : ",end='')
        inp = input()
        if inp == "0":
            break
        elif inp == "1":
            print("input new value : ", end='')
            lst.add_first(int(input()))
        elif inp == "2":
            print("input new value : ", end='')
            lst.add_last(int(input()))
        elif inp == "3" or inp == "4":
            print("input node value : ",end='')
            node = lst.find_node(int(input()))
            if node != None:
                if inp == "3":
                    print("input new value : ", end='')
                    lst.add_after(node, int(input()))
                else:
                    print("input new value : ", end='')
                    lst.add_before(node, int(input()))

        elif inp == "5":
            lst.remove_first()
        elif inp == "6":
            lst.remove_last()
        elif inp == "7":
            print("input node value : ",end='')
            node = lst.find_node(int(input()))
            if node != None:
                lst.remove(node)