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)
64
self._visitable = set(self._graph)
66
# self._original_graph = dict(graph)
68
# this is a stack storing the depth first search into the graph.
69
self._node_name_stack = []
70
# at each level of 'recursion' we have to check each parent. This
71
# stack stores the parents we have not yet checked for the node at the
72
# matching depth in _node_name_stack
73
self._pending_parents_stack = []
74
# this is a set of the completed nodes for fast checking whether a
75
# parent in a node we are processing on the stack has already been
76
# emitted and thus can be skipped.
77
self._completed_node_names = set()
79
80
"""Sort the graph and return as a list.
81
82
After calling this the sorter is empty and you must create a new one.
83
84
return list(self.iter_topo_order())
95
96
def iter_topo_order(self):
96
97
"""Yield the nodes of the graph in a topological order.
98
99
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
103
# 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
104
# top of the depth first search stack.
105
node_name, parents = self._graph.popitem()
106
self._push_node(node_name, parents)
107
while self._node_name_stack:
108
# loop until this call completes.
109
parents_to_visit = self._pending_parents_stack[-1]
110
# if all parents are done, the revision is done
127
111
if not parents_to_visit:
128
112
# 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)
113
# all the nodes parents have been added to the output, now
114
# we can add it to the output.
115
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))
117
while self._pending_parents_stack[-1]:
118
# recurse depth first into a single parent
119
next_node_name = self._pending_parents_stack[-1].pop()
120
if next_node_name in self._completed_node_names:
121
# this parent was completed by a child on the
122
# call stack. skip it.
124
if next_node_name not in self._visitable:
126
# otherwise transfer it from the source graph into the
127
# top of the current depth first search stack.
129
parents = self._graph.pop(next_node_name)
131
# if the next node is not in the source graph it has
132
# already been popped from it and placed into the
133
# current search stack (but not completed or we would
134
# have hit the continue 4 lines up.
135
# this indicates a cycle.
136
raise errors.GraphCycleError(self._node_name_stack)
137
self._push_node(next_node_name, parents)
138
# and do not continue processing parents until this 'call'
142
def _push_node(self, node_name, parents):
143
"""Add node_name to the pending node stack.
145
Names in this stack will get emitted into the output as they are popped
148
self._node_name_stack.append(node_name)
149
self._pending_parents_stack.append(list(parents))
152
"""Pop the top node off the stack
154
The node is appended to the sorted output.
156
# we are returning from the flattened call frame:
157
# pop off the local variables
158
node_name = self._node_name_stack.pop()
159
self._pending_parents_stack.pop()
161
self._completed_node_names.add(node_name)
161
165
def merge_sort(graph, branch_tip, mainline_revisions=None, generate_revno=False):
162
166
"""Topological sort a graph which groups merges.
164
168
:param graph: sequence of pairs of node->parents_list.
165
:param branch_tip: the tip of the branch to graph. Revisions not
169
:param branch_tip: the tip of the branch to graph. Revisions not
166
170
reachable from branch_tip are not included in the
168
172
:param mainline_revisions: If not None this forces a mainline to be
229
232
The result is a list sorted so that all parents come before
230
233
their children. Each element of the list is a tuple containing:
231
234
(sequence_number, node_name, merge_depth, end_of_merge)
232
* sequence_number: The sequence of this row in the output. Useful for
235
* sequence_number: The sequence of this row in the output. Useful for
234
237
* node_name: The node name: opaque text to the merge routine.
235
238
* merge_depth: How many levels of merging deep this node has been
237
240
* revno_sequence: When requested this field provides a sequence of
238
241
revision numbers for all revisions. The format is:
239
(REVNO, BRANCHNUM, BRANCHREVNO). BRANCHNUM is the number of the
242
REVNO[[.BRANCHREVNO.REVNO] ...]. BRANCHREVNO is the number of the
240
243
branch that the revno is on. From left to right the REVNO numbers
241
244
are the sequence numbers within that branch of the revision.
242
245
For instance, the graph {A:[], B:['A'], C:['A', 'B']} will get
282
285
C is the end of a cluster due to rule 1.
283
D is not the end of a cluster from rule 1, but is from rule 2: E
286
D is not the end of a cluster from rule 1, but is from rule 2: E
284
287
is not its left most ancestor
285
288
E is the end of a cluster due to rule 1
286
289
F might be but we need more data.
288
291
we show connecting lines to a parent when:
289
292
- The parent is the start of a merge within this cluster.
290
That is, the merge was not done to the mainline before this cluster
293
That is, the merge was not done to the mainline before this cluster
291
294
was merged to the mainline.
292
295
This can be detected thus:
293
* The parent has a higher merge depth and is the next revision in
296
* The parent has a higher merge depth and is the next revision in
296
299
The next revision in the list constraint is needed for this case:
298
B 1 [C, F] # we do not want to show a line to F which is depth 2
301
B 1 [C, F] # we do not want to show a line to F which is depth 2
300
C 1 [H] # note that this is a long line to show back to the
303
C 1 [H] # note that this is a long line to show back to the
301
304
ancestor - see the end of merge rules.
365
362
self._original_graph = dict(self._graph.items())
366
363
# we need to know the revision numbers of revisions to determine
367
364
# the revision numbers of their descendants
368
# this is a graph from node to [revno_tuple, first_child]
369
# where first_child is True if no other children have seen this node
365
# this is a graph from node to [revno_tuple, sequence_number]
366
# where sequence is the number of branches made from the node,
370
367
# and revno_tuple is the tuple that was assigned to the node.
371
368
# we dont know revnos to start with, so we start it seeded with
373
self._revnos = dict((revision, [None, True])
374
for revision in self._graph)
375
# Each mainline revision counts how many child branches have spawned from it.
376
self._revno_to_branch_count = {}
370
self._revnos = dict((revision, [None, 0]) for revision in self._graph)
371
# the global implicit root node has revno 0, but we need to know
372
# the sequence number for it too:
373
self._root_sequence = 0
378
375
# this is a stack storing the depth first search into the graph.
379
376
self._node_name_stack = []
380
377
# at each level of recursion we need the merge depth this node is at:
381
378
self._node_merge_depth_stack = []
382
379
# at each level of 'recursion' we have to check each parent. This
383
# stack stores the parents we have not yet checked for the node at the
380
# stack stores the parents we have not yet checked for the node at the
384
381
# matching depth in _node_name_stack
385
382
self._pending_parents_stack = []
386
383
# When we first look at a node we assign it a seqence number from its
387
384
# leftmost parent.
388
self._first_child_stack = []
385
self._assigned_sequence_stack = []
389
386
# this is a set of the nodes who have been completely analysed for fast
390
387
# membership checking
391
388
self._completed_node_names = set()
401
# the scheduling order is: F, E, D, C, B, A
398
# the scheduling order is: F, E, D, C, B, A
402
399
# that is - 'left subtree, right subtree, node'
403
400
# which would mean that when we schedule A we can emit the entire tree.
404
401
self._scheduled_nodes = []
405
# This records for each node when we have processed its left most
402
# This records for each node when we have processed its left most
406
403
# unmerged subtree. After this subtree is scheduled, all other subtrees
407
404
# have their merge depth increased by one from this nodes merge depth.
408
405
# it contains tuples - name, merge_depth
409
406
self._left_subtree_pushed_stack = []
411
408
# seed the search with the tip of the branch
412
if (branch_tip is not None and
413
branch_tip != _mod_revision.NULL_REVISION and
414
branch_tip != (_mod_revision.NULL_REVISION,)):
409
if branch_tip is not None:
415
410
parents = self._graph.pop(branch_tip)
416
411
self._push_node(branch_tip, 0, parents)
418
413
def sorted(self):
419
414
"""Sort the graph and return as a list.
421
416
After calling this the sorter is empty and you must create a new one.
423
418
return list(self.iter_topo_order())
425
420
def iter_topo_order(self):
426
421
"""Yield the nodes of the graph in a topological order.
428
423
After finishing iteration the sorter is empty and you cannot continue
459
455
node_merge_depth_stack_append(merge_depth)
460
456
left_subtree_pushed_stack_append(False)
461
457
pending_parents_stack_append(list(parents))
462
# as we push it, check if it is the first child
458
# as we push it, assign it a sequence number against its parent:
459
parents = original_graph[node_name]
465
461
# node has parents, assign from the left most parent.
467
parent_info = revnos[parents[0]]
469
# Left-hand parent is a ghost, consider it not to exist
471
if parent_info is not None:
472
first_child = parent_info[1]
473
parent_info[1] = False
462
parent_revno = revnos[parents[0]]
463
sequence = parent_revno[1]
475
# We don't use the same algorithm here, but we need to keep the
478
first_child_stack_append(first_child)
466
# no parents, use the root sequence
467
sequence = self._root_sequence
468
self._root_sequence +=1
469
assigned_sequence_stack_append(sequence)
480
471
def pop_node(node_name_stack_pop=node_name_stack.pop,
481
472
node_merge_depth_stack_pop=node_merge_depth_stack.pop,
482
first_child_stack_pop=self._first_child_stack.pop,
473
assigned_sequence_stack_pop=self._assigned_sequence_stack.pop,
483
474
left_subtree_pushed_stack_pop=left_subtree_pushed_stack.pop,
484
475
pending_parents_stack_pop=pending_parents_stack.pop,
485
476
original_graph=self._original_graph,
486
477
revnos=self._revnos,
487
478
completed_node_names_add=self._completed_node_names.add,
488
479
scheduled_nodes_append=scheduled_nodes.append,
489
revno_to_branch_count=self._revno_to_branch_count,
491
481
"""Pop the top node off the stack
496
486
# pop off the local variables
497
487
node_name = node_name_stack_pop()
498
488
merge_depth = node_merge_depth_stack_pop()
499
first_child = first_child_stack_pop()
489
sequence = assigned_sequence_stack_pop()
500
490
# remove this node from the pending lists:
501
491
left_subtree_pushed_stack_pop()
502
492
pending_parents_stack_pop()
504
494
parents = original_graph[node_name]
507
496
# node has parents, assign from the left most parent.
509
parent_revno = revnos[parents[0]][0]
511
# left-hand parent is a ghost, treat it as not existing
513
if parent_revno is not None:
497
parent_revno = revnos[parents[0]]
515
499
# not the first child, make a new branch
516
base_revno = parent_revno[0]
517
branch_count = revno_to_branch_count.get(base_revno, 0)
519
revno_to_branch_count[base_revno] = branch_count
520
revno = (parent_revno[0], branch_count, 1)
521
# revno = (parent_revno[0], branch_count, parent_revno[-1]+1)
500
revno = parent_revno[0] + (sequence, 1)
523
# as the first child, we just increase the final revision
525
revno = parent_revno[:-1] + (parent_revno[-1] + 1,)
502
# increment the sequence number within the branch
503
revno = parent_revno[0][:-1] + (parent_revno[0][-1] + 1,)
527
505
# no parents, use the root sequence
528
root_count = revno_to_branch_count.get(0, -1)
531
revno = (0, root_count, 1)
507
# make a parallel import revision number
508
revno = (0, sequence, 1)
534
revno_to_branch_count[0] = root_count
536
512
# store the revno for this node for future reference
537
513
revnos[node_name][0] = revno
554
530
if not left_subtree_pushed_stack[-1]:
555
531
# recurse depth first into the primary parent
556
532
next_node_name = pending_parents_stack[-1].pop(0)
557
is_left_subtree = True
558
left_subtree_pushed_stack[-1] = True
560
534
# place any merges in right-to-left order for scheduling
561
535
# which gives us left-to-right order after we reverse
562
# the scheduled queue. XXX: This has the effect of
536
# the scheduled queue. XXX: This has the effect of
563
537
# allocating common-new revisions to the right-most
564
# subtree rather than the left most, which will
538
# subtree rather than the left most, which will
565
539
# display nicely (you get smaller trees at the top
566
540
# of the combined merge).
567
541
next_node_name = pending_parents_stack[-1].pop()
568
is_left_subtree = False
569
542
if next_node_name in completed_node_names:
570
543
# this parent was completed by a child on the
571
544
# call stack. skip it.
640
610
self._node_merge_depth_stack.append(merge_depth)
641
611
self._left_subtree_pushed_stack.append(False)
642
612
self._pending_parents_stack.append(list(parents))
643
# as we push it, figure out if this is the first child
613
# as we push it, assign it a sequence number against its parent:
614
parents = self._original_graph[node_name]
646
616
# node has parents, assign from the left most parent.
648
parent_info = self._revnos[parents[0]]
650
# Left-hand parent is a ghost, consider it not to exist
652
if parent_info is not None:
653
first_child = parent_info[1]
654
parent_info[1] = False
617
parent_revno = self._revnos[parents[0]]
618
sequence = parent_revno[1]
656
# We don't use the same algorithm here, but we need to keep the
659
self._first_child_stack.append(first_child)
621
# no parents, use the root sequence
622
sequence = self._root_sequence
623
self._root_sequence +=1
624
self._assigned_sequence_stack.append(sequence)
661
626
def _pop_node(self):
662
"""Pop the top node off the stack
627
"""Pop the top node off the stack
664
629
The node is appended to the sorted output.
667
632
# pop off the local variables
668
633
node_name = self._node_name_stack.pop()
669
634
merge_depth = self._node_merge_depth_stack.pop()
670
first_child = self._first_child_stack.pop()
635
sequence = self._assigned_sequence_stack.pop()
671
636
# remove this node from the pending lists:
672
637
self._left_subtree_pushed_stack.pop()
673
638
self._pending_parents_stack.pop()
675
640
parents = self._original_graph[node_name]
678
642
# node has parents, assign from the left most parent.
680
parent_revno = self._revnos[parents[0]][0]
682
# left-hand parent is a ghost, treat it as not existing
684
if parent_revno is not None:
643
parent_revno = self._revnos[parents[0]]
686
645
# not the first child, make a new branch
687
base_revno = parent_revno[0]
688
branch_count = self._revno_to_branch_count.get(base_revno, 0)
690
self._revno_to_branch_count[base_revno] = branch_count
691
revno = (parent_revno[0], branch_count, 1)
692
# revno = (parent_revno[0], branch_count, parent_revno[-1]+1)
646
revno = parent_revno[0] + (sequence, 1)
694
# as the first child, we just increase the final revision
696
revno = parent_revno[:-1] + (parent_revno[-1] + 1,)
648
# increment the sequence number within the branch
649
revno = parent_revno[0][:-1] + (parent_revno[0][-1] + 1,)
698
651
# no parents, use the root sequence
699
root_count = self._revno_to_branch_count.get(0, 0)
700
root_count = self._revno_to_branch_count.get(0, -1)
703
revno = (0, root_count, 1)
653
# make a parallel import revision number
654
revno = (0, sequence, 1)
706
self._revno_to_branch_count[0] = root_count
708
658
# store the revno for this node for future reference
709
659
self._revnos[node_name][0] = revno
added
removed
bzrlib/tsort.py
