def make_context(data, base=None, prev=None):
"""Create and return a filter list for some tuple rule.
:param data: a list of items. These items are one of the following:
- ``None``, which signals that `base` should be used.
- ``True``, which signals that `prev` should be used.
- an arbitrary object, which is sent to `filters.auto`.
The result is "and"-ed with `base`, if `base` is
defined.
:param base: the corresponding base filter.
:param prev: the corresponding filter created on the previous tuple.
"""
returned = []
for i, datum in enumerate(data):
if datum is None:
result = base[i]
elif datum is True:
result = prev[i]
else:
extension = F.auto(datum)
try:
b = base[i]
except IndexError:
b = None
if b is None or b is F.allow_all:
result = extension
else:
result = extension & b
returned.append(result)
return returned
def _make_window(row, anuvrtti, prev_rule):
returned = []
base_args = anuvrtti.base_args
prev_window = prev_rule.window if prev_rule else ([None], [None], [None])
for base, item, p_item in zip(base_args, row.window, prev_window):
if item is Shesha:
item = None
if not hasattr(item, '__iter__'):
item = [item]
returned.append(make_context(item, base=[F.auto(base)], prev=p_item))
return returned
