def test_is_predicate(self):
class dummyPred:
def __call__(self, item):
pass
def __str__(self):
return "dummyPred"
pred = dummyPred()
assert predicates.is_predicate(
pred), "a class with call and str methods satisfies is_predicate()"
pred = object()
assert not predicates.is_predicate(
pred
), "a class without call and str doesn't satisfy is_predicate()"
pred = predicates.predicate()
assert predicates.is_predicate(
pred), "an instance of predicate satisfies is_predicate()"
pred = predicates.equal_to(1)
assert predicates.is_predicate(
pred
), "an instance of a subclass of predicate satisfies is_predicate()"
def __get_index(self, start):
"""
finds the index that start specifies
Args:
start: an indicator of a position in an order can be a predicate or an index in
the ordering
Returns:
the index in the given list that start refers to
"""
if predicates.is_predicate(start):
index = 0
while index < self.size() and not start(self.objects[index]):
index += 1
return index
else:
return start
def __init__(self, filter_pred=None):
"""
Constructor used to set-up history. If the history is given a filter, it will ignore (drop)
objects that don't satisfy the filter predicate.
Args:
filter_pred: an optional predicate to filter incoming data_objects
"""
self.objects = []
self.filter = predicates.always_true()
if filter_pred is not None:
if predicates.is_predicate(filter_pred):
self.filter = filter_pred
else:
raise TypeError(
"The given filter was an instance of predicate.")
self.retrieved_cursor = 0
def __get_index(self, start, ordered):
"""
finds the index that start specifies
Args:
start: an indicator of a position in an order can be a predicate, a TimeType time
stamp or an index in the ordering
ordered: the list to clear
Returns:
the index in the given list that start refers to
"""
if predicates.is_predicate(start):
index = 0
while index < len(ordered) and not start(ordered[index]):
index += 1
return index
elif isinstance(start, TimeType):
index = 0
while index < len(ordered) and ordered[index].get_time() < start:
index += 1
return index
else:
return start
