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"""
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 <http://www.gnu.org/licenses/>.
Copyright 2010 Sebastian Spaeth <Sebastian@SSpaeth.de>'
"""
from ctypes import c_char_p
from notmuch.globals import nmlib, STATUS, NotmuchError
class Tags(object):
"""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:`NotmuchError`
STATUS.NOT_INITIALIZED. 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.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:`NotmuchError`
(STATUS.NULL_POINTER) 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 tags_p is None:
raise NotmuchError(STATUS.NULL_POINTER)
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
def next(self):
if self._tags is None:
raise NotmuchError(STATUS.NOT_INITIALIZED)
if not nmlib.notmuch_tags_valid(self._tags):
self._tags = None
raise StopIteration
tag = Tags._get(self._tags).decode('UTF-8')
nmlib.notmuch_tags_move_to_next(self._tags)
return tag
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 nmlib.notmuch_tags_valid(self._tags) > 0
def __str__(self):
"""The str() representation of Tags() is 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:`NotmuchError` STATUS.NOT_INITIALIZED on
subsequent attempts.
"""
return " ".join(self)
def __del__(self):
"""Close and free the notmuch tags"""
if self._tags is not None:
nmlib.notmuch_tags_destroy(self._tags)
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