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from sqlalchemy.util import jython, function_named, defaultdict
import gc
import time
import random
if jython:
def gc_collect(*args):
"""aggressive gc.collect for tests."""
gc.collect()
time.sleep(0.1)
gc.collect()
gc.collect()
return 0
# "lazy" gc, for VM's that don't GC on refcount == 0
lazy_gc = gc_collect
else:
# assume CPython - straight gc.collect, lazy_gc() is a pass
gc_collect = gc.collect
def lazy_gc():
pass
def picklers():
picklers = set()
# Py2K
try:
import cPickle
picklers.add(cPickle)
except ImportError:
pass
# end Py2K
import pickle
picklers.add(pickle)
# yes, this thing needs this much testing
for pickle in picklers:
for protocol in -1, 0, 1, 2:
yield pickle.loads, lambda d:pickle.dumps(d, protocol)
def round_decimal(value, prec):
if isinstance(value, float):
return round(value, prec)
import decimal
# can also use shift() here but that is 2.6 only
return (value * decimal.Decimal("1" + "0" * prec)).to_integral(decimal.ROUND_FLOOR) / \
pow(10, prec)
class RandomSet(set):
def __iter__(self):
l = list(set.__iter__(self))
random.shuffle(l)
return iter(l)
def pop(self):
index = random.randint(0, len(self) - 1)
item = list(set.__iter__(self))[index]
self.remove(item)
return item
def union(self, other):
return RandomSet(set.union(self, other))
def difference(self, other):
return RandomSet(set.difference(self, other))
def intersection(self, other):
return RandomSet(set.intersection(self, other))
def copy(self):
return RandomSet(self)
def conforms_partial_ordering(tuples, sorted_elements):
"""True if the given sorting conforms to the given partial ordering."""
deps = defaultdict(set)
for parent, child in tuples:
deps[parent].add(child)
for i, node in enumerate(sorted_elements):
for n in sorted_elements[i:]:
if node in deps[n]:
return False
else:
return True
def all_partial_orderings(tuples, elements):
edges = defaultdict(set)
for parent, child in tuples:
edges[child].add(parent)
def _all_orderings(elements):
if len(elements) == 1:
yield list(elements)
else:
for elem in elements:
subset = set(elements).difference([elem])
if not subset.intersection(edges[elem]):
for sub_ordering in _all_orderings(subset):
yield [elem] + sub_ordering
return iter(_all_orderings(elements))
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