Node.py

"""
node.py
author: James heliotis
description: A linkable node class for use in stacks, queues, and linked lists
"""

class Node:

    __slots__ = "value", "link"

    def __init__( self, value, link = None ):
        """ Create a new node and optionally link it to an existing one.
            param value: the value to be stored in the new node
            param link: the node linked to this one
        """
        self.value = value
        self.link = link

    def __str__( self ):
        """ Return a string representation of the contents of
            this node. The link is not included.
        """
        return str( self.value )

    def __repr__( self ):
        """ Return a string that, if evaluated, would recreate
            this node and the node to which it is linked.
            This function should not be called for a circular
            list.
        """
        return "Node(" + repr( self.value ) + "," + \
               repr( self.link ) + ")"

def size_to_end( node ):
    """ Count how many nodes from this one to a node whose link is None.
        return: the length of the list starting at node
    """
    if node == None:
        return 0
    else:
        return 1 + size_to_end( node.link )

def test():
    nodes = Node( 1, Node( "two", Node( 3.0 ) ) )
    n = nodes
    while n != None:
        print( n.value )
        n = n.link
    print( "\n" + str( size_to_end( nodes ) ) + " nodes.\n" )
    print( nodes )
    print( repr( nodes ) )

if __name__ == "__main__":
    test()