def tags(self):
"""Return an immutable set with all tags used in this database.
This returns an immutable set-like object implementing the
collections.abc.Set Abstract Base Class. Due to the
underlying libnotmuch implementation some operations have
different performance characteristics then plain set objects.
Mainly any lookup operation is O(n) rather then O(1).
Normal usage treats tags as UTF-8 encoded unicode strings so
they are exposed to Python as normal unicode string objects.
If you need to handle tags stored in libnotmuch which are not
valid unicode do check the :class:`ImmutableTagSet` docs for
how to handle this.
:rtype: ImmutableTagSet
:raises ObjectDestroyedError: if used after destroyed.
"""
try:
ref = self._cached_tagset
except AttributeError:
tagset = None
else:
tagset = ref()
if tagset is None:
tagset = tags.ImmutableTagSet(
self, '_db_p', capi.lib.notmuch_database_get_all_tags)
self._cached_tagset = weakref.ref(tagset)
return tagset
def collect_tags(self):
"""Return the tags of messages matching this query."""
msgs_pp = capi.ffi.new('notmuch_messages_t**')
ret = capi.lib.notmuch_query_search_messages(self._query_p, msgs_pp)
if ret != capi.lib.NOTMUCH_STATUS_SUCCESS:
raise errors.NotmuchError(ret)
self._msgs_p = msgs_pp[0]
tagset = tags.ImmutableTagSet(self, '_msgs_p',
capi.lib.notmuch_messages_collect_tags)
return tags.ImmutableTagSet._from_iterable(tagset)