""" This file is part of notmuch. Notmuch is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. Notmuch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with notmuch. If not, see . Copyright 2010 Sebastian Spaeth """ from ctypes import c_char_p from notmuch.globals import ( nmlib, Python3StringMixIn, NotmuchTagsP, ) from .errors import ( NullPointerError, NotInitializedError, ) class Tags(Python3StringMixIn): """Represents a list of notmuch tags This object provides an iterator over a list of notmuch tags (which are unicode instances). Do note that the underlying library only provides a one-time iterator (it cannot reset the iterator to the start). Thus iterating over the function will "exhaust" the list of tags, and a subsequent iteration attempt will raise a :exc:`NotInitializedError`. Also note, that any function that uses iteration (nearly all) will also exhaust the tags. So both:: for tag in tags: print tag as well as:: number_of_tags = len(tags) and even a simple:: #str() iterates over all tags to construct a space separated list print(str(tags)) will "exhaust" the Tags. If you need to re-iterate over a list of tags you will need to retrieve a new :class:`Tags` object. """ #notmuch_tags_get _get = nmlib.notmuch_tags_get _get.argtypes = [NotmuchTagsP] _get.restype = c_char_p def __init__(self, tags_p, parent=None): """ :param tags_p: A pointer to an underlying *notmuch_tags_t* structure. These are not publically exposed, so a user will almost never instantiate a :class:`Tags` object herself. They are usually handed back as a result, e.g. in :meth:`Database.get_all_tags`. *tags_p* must be valid, we will raise an :exc:`NullPointerError` if it is `None`. :type tags_p: :class:`ctypes.c_void_p` :param parent: The parent object (ie :class:`Database` or :class:`Message` these tags are derived from, and saves a reference to it, so we can automatically delete the db object once all derived objects are dead. :TODO: Make the iterator optionally work more than once by cache the tags in the Python object(?) """ if not tags_p: raise NullPointerError() self._tags = tags_p #save reference to parent object so we keep it alive self._parent = parent def __iter__(self): """ Make Tags an iterator """ return self _valid = nmlib.notmuch_tags_valid _valid.argtypes = [NotmuchTagsP] _valid.restype = bool _move_to_next = nmlib.notmuch_tags_move_to_next _move_to_next.argtypes = [NotmuchTagsP] _move_to_next.restype = None def __next__(self): if not self._tags: raise NotInitializedError() if not self._valid(self._tags): self._tags = None raise StopIteration tag = Tags._get(self._tags).decode('UTF-8') self._move_to_next(self._tags) return tag next = __next__ # python2.x iterator protocol compatibility def __nonzero__(self): """Implement bool(Tags) check that can be repeatedly used If __nonzero__ is not implemented, "if Tags()" will implicitly call __len__, using up our iterator, so it is important that this function is defined. :returns: True if the Tags() iterator has at least one more Tag left.""" return self._valid(self._tags) > 0 def __unicode__(self): """string representation of :class:`Tags`: a space separated list of tags .. note:: As this iterates over the tags, we will not be able to iterate over them again (as in retrieve them)! If the tags have been exhausted already, this will raise a :exc:`NotInitializedError`on subsequent attempts. """ return " ".join(self) _destroy = nmlib.notmuch_tags_destroy _destroy.argtypes = [NotmuchTagsP] _destroy.restype = None def __del__(self): """Close and free the notmuch tags""" if self._tags is not None: self._destroy(self._tags)