relate.py

#!/usr/bin/python

# TODO: Construct a topological ordering for the pushes so they happen
# correctly regardless of their order in the relations.txt file

import re
import sys
import os.path
from exeption import ValueError

class Graph(object):

	def __init__(self):
		pass

	def add_edge(self, pusher, receiver):
		pass

	def remove_edge(self, start, end):
		pass

	def has_edges(self):
		pass

	def get_edges(self, node):
		pass

	def get_source_nodes(self):
		# set(graph) - set(node for node in graph[key] for key in graph)
		pass

def parse_line(line, graph):
	# Remove everything after the first '#'
	first_comment = line.find("#")
	line = line[:first_comment]

	match = re.match(r'(.*) -> (.*)', line)
	if match:
		pusher = match.group(1)
		receiver = match.group(2)

		graph.add_node(pusher, receiver)

	return graph

def topological_sort(graph):
	sorted_list = []
	source_nodes = graph.get_source_nodes()

	while source_nodes:
		node = source_nodes.pop()
		sorted_list.append(node)

		for end_node in graph.get_edges(node):
			graph.remove_edge(node, end_node)

			if graph.is_source(end_node):
				source_nodes.add(end_node)

	if graph.has_edges():
		raise ValueError("Graph is not a DAG; it has cycles.")

	return sorted_list


		# try:
		# 	with open(pusher) as f1, open(receiver) as f2:
		# 		pusher_set = set(f1.readlines())
		# 		pushed_set = set(f2.readlines())
		# except IOError as e:
		# 	print e
		# 	print "Invalid relations.txt -- exiting"
		# 	sys.exit(1)
          #
		# print match.group(0)
		# print "-----------------------------------"
		# with open(receiver, 'a') as out:
		# 	print "".join(pusher_set - pushed_set)
		# 	out.writelines(pusher_set - pushed_set)
		# print

with open("/home/thomas/.cmus/relations.txt") as f:
	lines = f.readlines()

for line in lines:
	parse_line(line)