queries.py 文件源码

def evaluate(self, query: MutableMapping[str, Any], context: PipelineContext = None) -> True:
        # This is a little weird. We have to handle the case of can_have("x").and_("y") here.
        # Since the only type of Node that can return False rather than just raising a
        # QueryValidationError is a KeyNode that isn't required, or an OrNode whose children
        # are all KeyNodes that aren't required, we can't short circuit on a False value. If
        # we have can_have("x").and_("y"), and only some are True, we want raise a
        # QueryValidationError. If all are True or all are False, everything's fine.
        all_true = True
        all_possible_false = True
        for child in self.children:
            is_true = child.evaluate(query, context)
            all_true = all_true and is_true
            if child.falsifiable:
                all_possible_false = all_possible_false and not is_true

        if all_possible_false or all_true:
            return True
        raise BoundKeyExistenceError("Query must have all or none of the elements joined with \"and\" in a \"can_have\" statement!")