listqueue.py

# Implementaton of the Queue ADT using a Python list.
class Queue:
    # Creates an empty queue.
    def  __init__( self ):
        self._qList = list()

    # Returns True if the queue is empty.
    def isEmpty( self ):
        return len( self ) == 0

    # Returns the number of items in the queue.
    def __len__( self ):
        return len( self._qList )

    # Adds the given item to the queue.
    def enqueue( self, item ):
        self._qList.append( item )
    # Removes and returns the first item in the queue.
    def dequeue( self ):
        assert not self.isEmpty(), "Cannot dequeue from an empty queue."
        return self._qList.pop(0)


if __name__ == '__main__':
    Q = Queue()
    Q.enqueue( 28 )
    Q.enqueue( 19 )
    Q.enqueue( 45 )
    Q.enqueue( 13 )
    Q.enqueue( 7 )

    for i in range( len(Q) ):
        cur_item = Q.dequeue()
        print cur_item,
    print ''