# cs4102lib.py module
# version 1.0, March 15 2010

from collections import deque

# based on http://docs.python.org/tutorial/datastructures.html#using-lists-as-queues
class Queue:
    def __init__(self, data=[]):
        self.qdata = deque(data)
        #print "In constr:", self.qdata

    def add(self, item):
        self.qdata.append(item)
        
    def remove(self):
        if len(self.qdata) == 0:
            return None
        item = self.qdata.popleft()
        return item
    
    def front(self):
        if len(self.qdata) == 0:
            return None
        return self.qdata[0]

    def __str__(self):
        return str(self.qdata)

    def __len__(self):
        return len(self.qdata)




class Graph:
    def __init__(self, adj_dict={}):
        self.adj_dict = adj_dict
        #print "In constr:", self.adj_dict

    def get_adjlist(self, vertex):
        return self.adj_dict.get(vertex, None)

    def is_adjacent(self, v1, v2):
        alist = self.adj_dict.get(v1, None)
        if alist == None: return False
        return v2 in alist

    def num_nodes(self):
        return len(self.adj_dict)

# returns number of edge "items" in adj. lists
# for digraph, this is number of edges.
# for undirected graph, this is 2 x number of edges
    def num_edge_items(self):
        sum = 0
        for v in self.adj_dict:
            sum = sum + len(self.adj_dict[v])
        return sum

    def __str__(self):
        return str(self.adj_dict)

    def __iter__(self):
        return iter(self.adj_dict)
    
    def __contains__(self, value):
        return value in self.adj_dict
    
    def __len__(self):
        return len(self.adj_dict)