40
def max_distance(node, ancestors, distances, root_descendants):
41
"""Calculate the max distance to an ancestor.
42
Return None if not all possible ancestors have known distances"""
45
best = distances[node]
46
for ancestor in ancestors[node]:
47
# skip ancestors we will never traverse:
48
if root_descendants is not None and ancestor not in root_descendants:
50
# An ancestor which is not listed in ancestors will never be in
51
# distances, so we pretend it never existed.
52
if ancestor not in ancestors:
54
if ancestor not in distances:
56
if best is None or distances[ancestor]+1 > best:
57
best = distances[ancestor] + 1
61
def node_distances(graph, ancestors, start, root_descendants=None):
62
"""Produce a list of nodes, sorted by distance from a start node.
63
This is an algorithm devised by Aaron Bentley, because applying Dijkstra
64
backwards seemed too complicated.
66
For each node, we walk its descendants. If all the descendant's ancestors
67
have a max-distance-to-start, (excluding ones that can never reach start),
68
we calculate their max-distance-to-start, and schedule their descendants.
70
So when a node's last parent acquires a distance, it will acquire a
71
distance on the next iteration.
73
Once we know the max distances for all nodes, we can return a list sorted
74
by distance, farthest first.
76
distances = {start: 0}
81
line_descendants = graph[line]
82
for descendant in line_descendants:
83
distance = max_distance(descendant, ancestors, distances,
87
distances[descendant] = distance
88
new_lines.add(descendant)
93
def nodes_by_distance(distances):
94
"""Return a list of nodes sorted by distance"""
98
node_list = distances.keys()
99
node_list.sort(key=by_distance, reverse=True)
103
def select_farthest(distances, common):
104
"""Return the farthest common node, or None if no node qualifies."""
105
node_list = nodes_by_distance(distances)
106
for node in node_list:
111
41
mail_map = {'aaron.bentley@utoronto.ca' : 'Aaron Bentley',
112
42
'abentley@panoramicfeedback.com': 'Aaron Bentley',
113
43
'abentley@lappy' : 'Aaron Bentley',
153
83
return new_ancestors
155
85
def get_rev_info(rev_id, source):
156
"""Return the committer, message, nick and date of a revision."""
86
"""Return the committer, message, and date of a revision."""
161
90
if rev_id == 'null:':
162
91
return None, 'Null Revision', None, None
added
removed
graph.py
