34
30
graph -- sequence of pairs of node->parents_list.
36
The result is a list of node names, such that all parents come before their
32
The result is a list of node names, such that all parents come before
39
35
node identifiers can be any hashable object, and are typically strings.
41
This function has the same purpose as the TopoSorter class, but uses a
42
different algorithm to sort the graph. That means that while both return a
43
list with parents before their child nodes, the exact ordering can be
46
topo_sort is faster when the whole list is needed, while when iterating
47
over a part of the list, TopoSorter.iter_topo_order should be used.
49
kg = _mod_graph.KnownGraph(dict(graph))
37
return TopoSorter(graph).sorted()
53
40
class TopoSorter(object):
55
42
def __init__(self, graph):
56
43
"""Topological sorting of a graph.
58
45
:param graph: sequence of pairs of node_name->parent_names_list.
59
46
i.e. [('C', ['B']), ('B', ['A']), ('A', [])]
60
47
For this input the output from the sort or
61
48
iter_topo_order routines will be:
64
51
node identifiers can be any hashable object, and are typically strings.
66
53
If you have a graph like [('a', ['b']), ('a', ['c'])] this will only use
69
56
The graph is sorted lazily: until you iterate or sort the input is
70
57
not processed other than to create an internal representation.
72
iteration or sorting may raise GraphCycleError if a cycle is present
59
iteration or sorting may raise GraphCycleError if a cycle is present
75
# store a dict of the graph.
62
# a dict of the graph.
76
63
self._graph = dict(graph)
65
# self._original_graph = dict(graph)
67
# this is a stack storing the depth first search into the graph.
68
self._node_name_stack = []
69
# at each level of 'recursion' we have to check each parent. This
70
# stack stores the parents we have not yet checked for the node at the
71
# matching depth in _node_name_stack
72
self._pending_parents_stack = []
73
# this is a set of the completed nodes for fast checking whether a
74
# parent in a node we are processing on the stack has already been
75
# emitted and thus can be skipped.
76
self._completed_node_names = set()
79
79
"""Sort the graph and return as a list.
81
81
After calling this the sorter is empty and you must create a new one.
83
83
return list(self.iter_topo_order())
95
95
def iter_topo_order(self):
96
96
"""Yield the nodes of the graph in a topological order.
98
98
After finishing iteration the sorter is empty and you cannot continue
102
visitable = set(graph)
104
# this is a stack storing the depth first search into the graph.
105
pending_node_stack = []
106
# at each level of 'recursion' we have to check each parent. This
107
# stack stores the parents we have not yet checked for the node at the
108
# matching depth in pending_node_stack
109
pending_parents_stack = []
111
# this is a set of the completed nodes for fast checking whether a
112
# parent in a node we are processing on the stack has already been
113
# emitted and thus can be skipped.
114
completed_node_names = set()
117
102
# now pick a random node in the source graph, and transfer it to the
118
# top of the depth first search stack of pending nodes.
119
node_name, parents = graph.popitem()
120
pending_node_stack.append(node_name)
121
pending_parents_stack.append(list(parents))
123
# loop until pending_node_stack is empty
124
while pending_node_stack:
125
parents_to_visit = pending_parents_stack[-1]
126
# if there are no parents left, the revision is done
103
# top of the depth first search stack.
104
node_name, parents = self._graph.popitem()
105
self._push_node(node_name, parents)
106
while self._node_name_stack:
107
# loop until this call completes.
108
parents_to_visit = self._pending_parents_stack[-1]
109
# if all parents are done, the revision is done
127
110
if not parents_to_visit:
128
111
# append the revision to the topo sorted list
129
# all the nodes parents have been added to the output,
130
# now we can add it to the output.
131
popped_node = pending_node_stack.pop()
132
pending_parents_stack.pop()
133
completed_node_names.add(popped_node)
112
# all the nodes parents have been added to the output, now
113
# we can add it to the output.
114
yield self._pop_node()
136
# recurse depth first into a single parent
137
next_node_name = parents_to_visit.pop()
139
if next_node_name in completed_node_names:
140
# parent was already completed by a child, skip it.
142
if next_node_name not in visitable:
143
# parent is not a node in the original graph, skip it.
146
# transfer it along with its parents from the source graph
147
# into the top of the current depth first search stack.
149
parents = graph.pop(next_node_name)
151
# if the next node is not in the source graph it has
152
# already been popped from it and placed into the
153
# current search stack (but not completed or we would
154
# have hit the continue 6 lines up). this indicates a
156
raise errors.GraphCycleError(pending_node_stack)
157
pending_node_stack.append(next_node_name)
158
pending_parents_stack.append(list(parents))
116
while self._pending_parents_stack[-1]:
117
# recurse depth first into a single parent
118
next_node_name = self._pending_parents_stack[-1].pop()
119
if next_node_name in self._completed_node_names:
120
# this parent was completed by a child on the
121
# call stack. skip it.
123
# otherwise transfer it from the source graph into the
124
# top of the current depth first search stack.
126
parents = self._graph.pop(next_node_name)
128
# if the next node is not in the source graph it has
129
# already been popped from it and placed into the
130
# current search stack (but not completed or we would
131
# have hit the continue 4 lines up.
132
# this indicates a cycle.
133
raise errors.GraphCycleError(self._node_name_stack)
134
self._push_node(next_node_name, parents)
135
# and do not continue processing parents until this 'call'
139
def _push_node(self, node_name, parents):
140
"""Add node_name to the pending node stack.
142
Names in this stack will get emitted into the output as they are popped
145
self._node_name_stack.append(node_name)
146
self._pending_parents_stack.append(list(parents))
149
"""Pop the top node off the stack
151
The node is appended to the sorted output.
153
# we are returning from the flattened call frame:
154
# pop off the local variables
155
node_name = self._node_name_stack.pop()
156
self._pending_parents_stack.pop()
158
self._completed_node_names.add(node_name)
161
162
def merge_sort(graph, branch_tip, mainline_revisions=None, generate_revno=False):
162
163
"""Topological sort a graph which groups merges.
164
165
:param graph: sequence of pairs of node->parents_list.
165
:param branch_tip: the tip of the branch to graph. Revisions not
166
:param branch_tip: the tip of the branch to graph. Revisions not
166
167
reachable from branch_tip are not included in the
168
169
:param mainline_revisions: If not None this forces a mainline to be
228
229
The result is a list sorted so that all parents come before
229
230
their children. Each element of the list is a tuple containing:
230
231
(sequence_number, node_name, merge_depth, end_of_merge)
231
* sequence_number: The sequence of this row in the output. Useful for
232
* sequence_number: The sequence of this row in the output. Useful for
233
234
* node_name: The node name: opaque text to the merge routine.
234
235
* merge_depth: How many levels of merging deep this node has been
236
237
* revno_sequence: When requested this field provides a sequence of
237
238
revision numbers for all revisions. The format is:
238
(REVNO, BRANCHNUM, BRANCHREVNO). BRANCHNUM is the number of the
239
REVNO[[.BRANCHREVNO.REVNO] ...]. BRANCHREVNO is the number of the
239
240
branch that the revno is on. From left to right the REVNO numbers
240
241
are the sequence numbers within that branch of the revision.
241
242
For instance, the graph {A:[], B:['A'], C:['A', 'B']} will get
281
282
C is the end of a cluster due to rule 1.
282
D is not the end of a cluster from rule 1, but is from rule 2: E
283
D is not the end of a cluster from rule 1, but is from rule 2: E
283
284
is not its left most ancestor
284
285
E is the end of a cluster due to rule 1
285
286
F might be but we need more data.
287
288
we show connecting lines to a parent when:
288
289
- The parent is the start of a merge within this cluster.
289
That is, the merge was not done to the mainline before this cluster
290
That is, the merge was not done to the mainline before this cluster
290
291
was merged to the mainline.
291
292
This can be detected thus:
292
* The parent has a higher merge depth and is the next revision in
293
* The parent has a higher merge depth and is the next revision in
295
296
The next revision in the list constraint is needed for this case:
297
B 1 [C, F] # we do not want to show a line to F which is depth 2
298
B 1 [C, F] # we do not want to show a line to F which is depth 2
299
C 1 [H] # note that this is a long line to show back to the
300
C 1 [H] # note that this is a long line to show back to the
300
301
ancestor - see the end of merge rules.
364
359
self._original_graph = dict(self._graph.items())
365
360
# we need to know the revision numbers of revisions to determine
366
361
# the revision numbers of their descendants
367
# this is a graph from node to [revno_tuple, first_child]
368
# where first_child is True if no other children have seen this node
362
# this is a graph from node to [revno_tuple, sequence_number]
363
# where sequence is the number of branches made from the node,
369
364
# and revno_tuple is the tuple that was assigned to the node.
370
365
# we dont know revnos to start with, so we start it seeded with
372
self._revnos = dict((revision, [None, True])
373
for revision in self._graph)
374
# Each mainline revision counts how many child branches have spawned from it.
375
self._revno_to_branch_count = {}
367
self._revnos = dict((revision, [None, 0]) for revision in self._graph)
368
# the global implicit root node has revno 0, but we need to know
369
# the sequence number for it too:
370
self._root_sequence = 0
377
372
# this is a stack storing the depth first search into the graph.
378
373
self._node_name_stack = []
379
374
# at each level of recursion we need the merge depth this node is at:
380
375
self._node_merge_depth_stack = []
381
376
# at each level of 'recursion' we have to check each parent. This
382
# stack stores the parents we have not yet checked for the node at the
377
# stack stores the parents we have not yet checked for the node at the
383
378
# matching depth in _node_name_stack
384
379
self._pending_parents_stack = []
385
380
# When we first look at a node we assign it a seqence number from its
386
381
# leftmost parent.
387
self._first_child_stack = []
382
self._assigned_sequence_stack = []
388
383
# this is a set of the nodes who have been completely analysed for fast
389
384
# membership checking
390
385
self._completed_node_names = set()
400
# the scheduling order is: F, E, D, C, B, A
395
# the scheduling order is: F, E, D, C, B, A
401
396
# that is - 'left subtree, right subtree, node'
402
397
# which would mean that when we schedule A we can emit the entire tree.
403
398
self._scheduled_nodes = []
404
# This records for each node when we have processed its left most
399
# This records for each node when we have processed its left most
405
400
# unmerged subtree. After this subtree is scheduled, all other subtrees
406
401
# have their merge depth increased by one from this nodes merge depth.
407
402
# it contains tuples - name, merge_depth
408
403
self._left_subtree_pushed_stack = []
410
405
# seed the search with the tip of the branch
411
if (branch_tip is not None and
412
branch_tip != _mod_revision.NULL_REVISION and
413
branch_tip != (_mod_revision.NULL_REVISION,)):
406
if branch_tip is not None:
414
407
parents = self._graph.pop(branch_tip)
415
408
self._push_node(branch_tip, 0, parents)
417
410
def sorted(self):
418
411
"""Sort the graph and return as a list.
420
413
After calling this the sorter is empty and you must create a new one.
422
415
return list(self.iter_topo_order())
424
417
def iter_topo_order(self):
425
418
"""Yield the nodes of the graph in a topological order.
427
420
After finishing iteration the sorter is empty and you cannot continue
458
452
node_merge_depth_stack_append(merge_depth)
459
453
left_subtree_pushed_stack_append(False)
460
454
pending_parents_stack_append(list(parents))
461
# as we push it, check if it is the first child
455
# as we push it, assign it a sequence number against its parent:
456
parents = original_graph[node_name]
464
458
# node has parents, assign from the left most parent.
466
parent_info = revnos[parents[0]]
468
# Left-hand parent is a ghost, consider it not to exist
470
if parent_info is not None:
471
first_child = parent_info[1]
472
parent_info[1] = False
459
parent_revno = revnos[parents[0]]
460
sequence = parent_revno[1]
474
# We don't use the same algorithm here, but we need to keep the
477
first_child_stack_append(first_child)
463
# no parents, use the root sequence
464
sequence = self._root_sequence
465
self._root_sequence +=1
466
assigned_sequence_stack_append(sequence)
479
468
def pop_node(node_name_stack_pop=node_name_stack.pop,
480
469
node_merge_depth_stack_pop=node_merge_depth_stack.pop,
481
first_child_stack_pop=self._first_child_stack.pop,
470
assigned_sequence_stack_pop=self._assigned_sequence_stack.pop,
482
471
left_subtree_pushed_stack_pop=left_subtree_pushed_stack.pop,
483
472
pending_parents_stack_pop=pending_parents_stack.pop,
484
473
original_graph=self._original_graph,
485
474
revnos=self._revnos,
486
475
completed_node_names_add=self._completed_node_names.add,
487
476
scheduled_nodes_append=scheduled_nodes.append,
488
revno_to_branch_count=self._revno_to_branch_count,
490
478
"""Pop the top node off the stack
495
483
# pop off the local variables
496
484
node_name = node_name_stack_pop()
497
485
merge_depth = node_merge_depth_stack_pop()
498
first_child = first_child_stack_pop()
486
sequence = assigned_sequence_stack_pop()
499
487
# remove this node from the pending lists:
500
488
left_subtree_pushed_stack_pop()
501
489
pending_parents_stack_pop()
503
491
parents = original_graph[node_name]
506
493
# node has parents, assign from the left most parent.
508
parent_revno = revnos[parents[0]][0]
510
# left-hand parent is a ghost, treat it as not existing
512
if parent_revno is not None:
494
parent_revno = revnos[parents[0]]
514
496
# not the first child, make a new branch
515
base_revno = parent_revno[0]
516
branch_count = revno_to_branch_count.get(base_revno, 0)
518
revno_to_branch_count[base_revno] = branch_count
519
revno = (parent_revno[0], branch_count, 1)
520
# revno = (parent_revno[0], branch_count, parent_revno[-1]+1)
497
revno = parent_revno[0] + (sequence, 1)
522
# as the first child, we just increase the final revision
524
revno = parent_revno[:-1] + (parent_revno[-1] + 1,)
499
# increment the sequence number within the branch
500
revno = parent_revno[0][:-1] + (parent_revno[0][-1] + 1,)
526
502
# no parents, use the root sequence
527
root_count = revno_to_branch_count.get(0, -1)
530
revno = (0, root_count, 1)
504
# make a parallel import revision number
505
revno = (0, sequence, 1)
533
revno_to_branch_count[0] = root_count
535
509
# store the revno for this node for future reference
536
510
revnos[node_name][0] = revno
553
527
if not left_subtree_pushed_stack[-1]:
554
528
# recurse depth first into the primary parent
555
529
next_node_name = pending_parents_stack[-1].pop(0)
556
is_left_subtree = True
557
left_subtree_pushed_stack[-1] = True
559
531
# place any merges in right-to-left order for scheduling
560
532
# which gives us left-to-right order after we reverse
561
# the scheduled queue. XXX: This has the effect of
533
# the scheduled queue. XXX: This has the effect of
562
534
# allocating common-new revisions to the right-most
563
# subtree rather than the left most, which will
535
# subtree rather than the left most, which will
564
536
# display nicely (you get smaller trees at the top
565
537
# of the combined merge).
566
538
next_node_name = pending_parents_stack[-1].pop()
567
is_left_subtree = False
568
539
if next_node_name in completed_node_names:
569
540
# this parent was completed by a child on the
570
541
# call stack. skip it.
639
607
self._node_merge_depth_stack.append(merge_depth)
640
608
self._left_subtree_pushed_stack.append(False)
641
609
self._pending_parents_stack.append(list(parents))
642
# as we push it, figure out if this is the first child
610
# as we push it, assign it a sequence number against its parent:
611
parents = self._original_graph[node_name]
645
613
# node has parents, assign from the left most parent.
647
parent_info = self._revnos[parents[0]]
649
# Left-hand parent is a ghost, consider it not to exist
651
if parent_info is not None:
652
first_child = parent_info[1]
653
parent_info[1] = False
614
parent_revno = self._revnos[parents[0]]
615
sequence = parent_revno[1]
655
# We don't use the same algorithm here, but we need to keep the
658
self._first_child_stack.append(first_child)
618
# no parents, use the root sequence
619
sequence = self._root_sequence
620
self._root_sequence +=1
621
self._assigned_sequence_stack.append(sequence)
660
623
def _pop_node(self):
661
"""Pop the top node off the stack
624
"""Pop the top node off the stack
663
626
The node is appended to the sorted output.
666
629
# pop off the local variables
667
630
node_name = self._node_name_stack.pop()
668
631
merge_depth = self._node_merge_depth_stack.pop()
669
first_child = self._first_child_stack.pop()
632
sequence = self._assigned_sequence_stack.pop()
670
633
# remove this node from the pending lists:
671
634
self._left_subtree_pushed_stack.pop()
672
635
self._pending_parents_stack.pop()
674
637
parents = self._original_graph[node_name]
677
639
# node has parents, assign from the left most parent.
679
parent_revno = self._revnos[parents[0]][0]
681
# left-hand parent is a ghost, treat it as not existing
683
if parent_revno is not None:
640
parent_revno = self._revnos[parents[0]]
685
642
# not the first child, make a new branch
686
base_revno = parent_revno[0]
687
branch_count = self._revno_to_branch_count.get(base_revno, 0)
689
self._revno_to_branch_count[base_revno] = branch_count
690
revno = (parent_revno[0], branch_count, 1)
691
# revno = (parent_revno[0], branch_count, parent_revno[-1]+1)
643
revno = parent_revno[0] + (sequence, 1)
693
# as the first child, we just increase the final revision
695
revno = parent_revno[:-1] + (parent_revno[-1] + 1,)
645
# increment the sequence number within the branch
646
revno = parent_revno[0][:-1] + (parent_revno[0][-1] + 1,)
697
648
# no parents, use the root sequence
698
root_count = self._revno_to_branch_count.get(0, 0)
699
root_count = self._revno_to_branch_count.get(0, -1)
702
revno = (0, root_count, 1)
650
# make a parallel import revision number
651
revno = (0, sequence, 1)
705
self._revno_to_branch_count[0] = root_count
707
655
# store the revno for this node for future reference
708
656
self._revnos[node_name][0] = revno
added
removed
bzrlib/tsort.py
