mercurial/ancestor.py
 author Gregory Szorc Wed, 01 Aug 2018 13:00:45 -0700 changeset 47112 e7aa113b14f77959ad4039d873b57100a4d56b31 parent 46888 f8b46245b26a574095a881c69bccae460286da69 child 49370 b6db2e80a9cea146fb51ee0f824bb9d65620c9c7 permissions -rw-r--r--
global: use pycompat.xrange() On Python 3, our module importer automatically rewrites xrange() to pycompat.xrange(). We want to move away from the custom importer on Python 3. This commit converts all instances of xrange() to use pycompat.xrange(). Differential Revision: https://phab.mercurial-scm.org/D4032
```
# ancestor.py - generic DAG ancestor algorithm for mercurial
#
# Copyright 2006 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import collections
import heapq

from .node import nullrev
from . import (
pycompat,
)

"""Returns a set with the heads of all common ancestors of all nodes,
heads(::nodes[0] and ::nodes[1] and ...) .

pfunc must return a list of parent vertices for a given vertex.
"""
if not isinstance(nodes, set):
nodes = set(nodes)
if nullrev in nodes:
return set()
if len(nodes) <= 1:
return nodes

allseen = (1 << len(nodes)) - 1
seen = [0] * (max(nodes) + 1)
for i, n in enumerate(nodes):
seen[n] = 1 << i
poison = 1 << (i + 1)

gca = set()
interesting = len(nodes)
nv = len(seen) - 1
while nv >= 0 and interesting:
v = nv
nv -= 1
if not seen[v]:
continue
sv = seen[v]
if sv < poison:
interesting -= 1
if sv == allseen:
sv |= poison
if v in nodes:
# history is linear
return {v}
if sv < poison:
for p in pfunc(v):
sp = seen[p]
if p == nullrev:
continue
if sp == 0:
seen[p] = sv
interesting += 1
elif sp != sv:
seen[p] |= sv
else:
for p in pfunc(v):
if p == nullrev:
continue
sp = seen[p]
if sp and sp < poison:
interesting -= 1
seen[p] = sv
return gca

def ancestors(pfunc, *orignodes):
"""
Returns the common ancestors of a and b that are furthest from a
root (as measured by longest path).

pfunc must return a list of parent vertices for a given vertex.
"""
def deepest(nodes):
interesting = {}
count = max(nodes) + 1
depth = [0] * count
seen = [0] * count
mapping = []
for (i, n) in enumerate(sorted(nodes)):
depth[n] = 1
b = 1 << i
seen[n] = b
interesting[b] = 1
mapping.append((b, n))
nv = count - 1
while nv >= 0 and len(interesting) > 1:
v = nv
nv -= 1
dv = depth[v]
if dv == 0:
continue
sv = seen[v]
for p in pfunc(v):
if p == nullrev:
continue
dp = depth[p]
nsp = sp = seen[p]
if dp <= dv:
depth[p] = dv + 1
if sp != sv:
interesting[sv] += 1
nsp = seen[p] = sv
if sp:
interesting[sp] -= 1
if interesting[sp] == 0:
del interesting[sp]
elif dv == dp - 1:
nsp = sp | sv
if nsp == sp:
continue
seen[p] = nsp
interesting.setdefault(nsp, 0)
interesting[nsp] += 1
interesting[sp] -= 1
if interesting[sp] == 0:
del interesting[sp]
interesting[sv] -= 1
if interesting[sv] == 0:
del interesting[sv]

if len(interesting) != 1:
return []

k = 0
for i in interesting:
k |= i
return set(n for (i, n) in mapping if k & i)

if len(gca) <= 1:
return gca
return deepest(gca)

class incrementalmissingancestors(object):
'''persistent state used to calculate missing ancestors incrementally

Although similar in spirit to lazyancestors below, this is a separate class
because trying to support contains and missingancestors operations with the
same internal data structures adds needless complexity.'''
def __init__(self, pfunc, bases):
self.bases = set(bases)
if not self.bases:
self.pfunc = pfunc

def hasbases(self):
'''whether the common set has any non-trivial bases'''
return self.bases and self.bases != {nullrev}

'''grow the ancestor set by adding new bases'''
self.bases.update(newbases)

def removeancestorsfrom(self, revs):
'''remove all ancestors of bases from the set revs (in place)'''
bases = self.bases
pfunc = self.pfunc
revs.difference_update(bases)
# nullrev is always an ancestor
if not revs:
return
# anything in revs > start is definitely not an ancestor of bases
# revs <= start needs to be investigated
start = max(bases)
keepcount = sum(1 for r in revs if r > start)
if len(revs) == keepcount:
# no revs to consider
return

for curr in pycompat.xrange(start, min(revs) - 1, -1):
if curr not in bases:
continue
bases.update(pfunc(curr))
if len(revs) == keepcount:
# no more potential revs to discard
break

def missingancestors(self, revs):
'''return all the ancestors of revs that are not ancestors of self.bases

This may include elements from revs.

Equivalent to the revset (::revs - ::self.bases). Revs are returned in
revision number order, which is a topological order.'''
revsvisit = set(revs)
basesvisit = self.bases
pfunc = self.pfunc
bothvisit = revsvisit.intersection(basesvisit)
revsvisit.difference_update(bothvisit)
if not revsvisit:
return []

start = max(max(revsvisit), max(basesvisit))
# At this point, we hold the invariants that:
# - revsvisit is the set of nodes we know are an ancestor of at least
#   one of the nodes in revs
# - basesvisit is the same for bases
# - bothvisit is the set of nodes we know are ancestors of at least one
#   of the nodes in revs and one of the nodes in bases. bothvisit and
#   revsvisit are mutually exclusive, but bothvisit is a subset of
#   basesvisit.
# Now we walk down in reverse topo order, adding parents of nodes
# already visited to the sets while maintaining the invariants. When a
# node is found in both revsvisit and basesvisit, it is removed from
# revsvisit and added to bothvisit. When revsvisit becomes empty, there
# are no more ancestors of revs that aren't also ancestors of bases, so
# exit.

missing = []
for curr in pycompat.xrange(start, nullrev, -1):
if not revsvisit:
break

if curr in bothvisit:
bothvisit.remove(curr)
# curr's parents might have made it into revsvisit through
# another path
for p in pfunc(curr):
continue

if curr in revsvisit:
missing.append(curr)
revsvisit.remove(curr)
thisvisit = revsvisit
othervisit = basesvisit
elif curr in basesvisit:
thisvisit = basesvisit
othervisit = revsvisit
else:
# not an ancestor of revs or bases: ignore
continue

for p in pfunc(curr):
if p == nullrev:
pass
elif p in othervisit or p in bothvisit:
# p is implicitly in thisvisit. This means p is or should be
# in bothvisit
else:
# visit later

missing.reverse()
return missing

class lazyancestors(object):
def __init__(self, pfunc, revs, stoprev=0, inclusive=False):
"""Create a new object generating ancestors for the given revs. Does
not generate revs lower than stoprev.

This is computed lazily starting from revs. The object supports
iteration and membership.

cl should be a changelog and revs should be an iterable. inclusive is
a boolean that indicates whether revs should be included. Revs lower
than stoprev will not be generated.

Result does not include the null revision."""
self._parentrevs = pfunc
self._initrevs = revs
self._stoprev = stoprev
self._inclusive = inclusive

# Initialize data structures for __contains__.
# For __contains__, we use a heap rather than a deque because
# (a) it minimizes the number of parentrevs calls made
# (b) it makes the loop termination condition obvious
# Python's heap is a min-heap. Multiply all values by -1 to convert it
# into a max-heap.
self._containsvisit = [-rev for rev in revs]
heapq.heapify(self._containsvisit)
if inclusive:
self._containsseen = set(revs)
else:
self._containsseen = set()

def __nonzero__(self):
"""False if the set is empty, True otherwise."""
try:
next(iter(self))
return True
except StopIteration:
return False

__bool__ = __nonzero__

def __iter__(self):
"""Generate the ancestors of _initrevs in reverse topological order.

If inclusive is False, yield a sequence of revision numbers starting
with the parents of each revision in revs, i.e., each revision is *not*
considered an ancestor of itself.  Results are in breadth-first order:
parents of each rev in revs, then parents of those, etc.

If inclusive is True, yield all the revs first (ignoring stoprev),
then yield all the ancestors of revs as when inclusive is False.
If an element in revs is an ancestor of a different rev it is not
yielded again."""
seen = set()
revs = self._initrevs
if self._inclusive:
for rev in revs:
yield rev
seen.update(revs)

parentrevs = self._parentrevs
stoprev = self._stoprev
visit = collections.deque(revs)

schedule = visit.append

while visit:
for parent in parentrevs(visit.popleft()):
if parent >= stoprev and parent not in seen:
schedule(parent)
see(parent)
yield parent

def __contains__(self, target):
"""Test whether target is an ancestor of self._initrevs."""
# Trying to do both __iter__ and __contains__ using the same visit
# heap and seen set is complex enough that it slows down both. Keep
# them separate.
seen = self._containsseen
if target in seen:
return True
# Only integer target is valid, but some callers expect 'None in self'
# to be False. So we explicitly allow it.
if target is None:
return False

parentrevs = self._parentrevs
visit = self._containsvisit
stoprev = self._stoprev
heappop = heapq.heappop
heappush = heapq.heappush

targetseen = False

while visit and -visit[0] > target and not targetseen:
for parent in parentrevs(-heappop(visit)):
if parent < stoprev or parent in seen:
continue
# We need to make sure we push all parents into the heap so
# that we leave it in a consistent state for future calls.
heappush(visit, -parent)
see(parent)
if parent == target:
targetseen = True

return targetseen
```