def __init__(self, attribute, container, negate):
self.attribute = attribute
self.container = container
self.negate = negate
if IColumn.providedBy(container):
self.containerClause = self._columnContainer
self.getArgs = self._columnArgs
elif IQuery.providedBy(container):
self.containerClause = self._queryContainer
self.getArgs = self._queryArgs
else:
self.containerClause = self._sequenceContainer
self.getArgs = self._sequenceArgs
def compare(left, right, op):
# interim: maybe we want objects later? right now strings should be fine
a = []
if IColumn.providedBy(right):
return TwoAttributeComparison(left, op, right)
elif right is None:
if op == '=':
negate = False
elif op == '!=':
negate = True
else:
raise TypeError(
"None/NULL does not work with %s comparison" % (op,))
return NullComparison(left, negate)
else:
# convert to constant usable in the database
return AttributeValueComparison(left, op, right)
def _like(self, negate, firstOther, *others):
others = (firstOther,) + others
likeParts = []
allValues = True
for other in others:
if IColumn.providedBy(other):
likeParts.append(LikeColumn(other))
allValues = False
elif other is None:
# LIKE NULL is a silly condition, but it's allowed.
likeParts.append(LikeNull())
allValues = False
else:
likeParts.append(LikeValue(other))
if allValues:
likeParts = [LikeValue(''.join(others))]
return LikeComparison(self, negate, likeParts)