+class TaskFilter(object):
+ """
+ A set of parameters to filter the task list with.
+ """
+
+ def __init__(self, filter_params=[]):
+ self.filter_params = filter_params
+
+ def add_filter(self, filter_str):
+ self.filter_params.append(filter_str)
+
+ def add_filter_param(self, key, value):
+ key = key.replace('__', '.')
+ self.filter_params.append('{0}:{1}'.format(key, value))
+
+ def get_filter_params(self):
+ return [f for f in self.filter_params if f]
+
+ def clone(self):
+ c = self.__class__()
+ c.filter_params = list(self.filter_params)
+ return c
+
+
+class TaskQuerySet(object):
+ """
+ Represents a lazy lookup for a task objects.
+ """
+
+ def __init__(self, warrior=None, filter_obj=None):
+ self.warrior = warrior
+ self._result_cache = None
+ self.filter_obj = filter_obj or TaskFilter()
+
+ def __deepcopy__(self, memo):
+ """
+ Deep copy of a QuerySet doesn't populate the cache
+ """
+ obj = self.__class__()
+ for k, v in self.__dict__.items():
+ if k in ('_iter', '_result_cache'):
+ obj.__dict__[k] = None
+ else:
+ obj.__dict__[k] = copy.deepcopy(v, memo)
+ return obj
+
+ def __repr__(self):
+ data = list(self[:REPR_OUTPUT_SIZE + 1])
+ if len(data) > REPR_OUTPUT_SIZE:
+ data[-1] = "...(remaining elements truncated)..."
+ return repr(data)
+
+ def __len__(self):
+ if self._result_cache is None:
+ self._result_cache = list(self)
+ return len(self._result_cache)
+
+ def __iter__(self):
+ if self._result_cache is None:
+ self._result_cache = self._execute()
+ return iter(self._result_cache)
+
+ def __getitem__(self, k):
+ if self._result_cache is None:
+ self._result_cache = list(self)
+ return self._result_cache.__getitem__(k)
+
+ def __bool__(self):
+ if self._result_cache is not None:
+ return bool(self._result_cache)
+ try:
+ next(iter(self))
+ except StopIteration:
+ return False
+ return True
+
+ def __nonzero__(self):
+ return type(self).__bool__(self)
+
+ def _clone(self, klass=None, **kwargs):
+ if klass is None:
+ klass = self.__class__
+ filter_obj = self.filter_obj.clone()
+ c = klass(warrior=self.warrior, filter_obj=filter_obj)
+ c.__dict__.update(kwargs)
+ return c
+
+ def _execute(self):
+ """
+ Fetch the tasks which match the current filters.
+ """
+ return self.warrior.filter_tasks(self.filter_obj)
+
+ def all(self):
+ """
+ Returns a new TaskQuerySet that is a copy of the current one.
+ """
+ return self._clone()