150 lines
4.8 KiB
Python
150 lines
4.8 KiB
Python
#
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# Gramps - a GTK+/GNOME based genealogy program
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#
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# Copyright (C) 2000-2007 Donald N. Allingham
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#
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#-------------------------------------------------------------------------
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#
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# Standard python modules
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#
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#-------------------------------------------------------------------------
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import cPickle as pickle
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#-------------------------------------------------------------------------
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#
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# GrampsCursor class
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#
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#-------------------------------------------------------------------------
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class GrampsCursor(object):
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"""
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Provide a basic iterator that allows the user to cycle through
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the elements in a particular map.
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A cursor should never be directly instantiated. Instead, in should be
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created by the database class.
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A cursor should only be used for a single pass through the
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database. If multiple passes are needed, multiple cursors
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should be used.
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"""
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def __init__(self):
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"""
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Instantiate the object. Note, this method should be overridden in
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derived classes that properly set self.cursor and self.source
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"""
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self.cursor = self.source = None
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def __getattr__(self, name):
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"""
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Return a method from the underlying cursor object, if it exists
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"""
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return getattr(self.cursor, name)
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def __enter__(self):
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"""
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Context manager enter method
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"""
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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"""
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Context manager exit method
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"""
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self.close()
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return exc_type is None
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def __iter__(self):
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"""
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Iterator
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"""
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data = self.first()
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while data:
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yield data
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data = self.next()
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def first(self, *args, **kwargs):
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"""
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Return the first (index, data) pair in the database.
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This should be called before the first call to next(). Note that the
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data return is in the format of the serialized format stored in the
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database, not in the more usable class object. The data should be
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converted to a class using the class's unserialize method.
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If no data is available, None is returned.
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"""
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data = self.cursor.first(*args, **kwargs)
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if data:
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return (data[0], pickle.loads(data[1]))
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return None
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def next(self, *args, **kwargs):
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"""
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Return the next (index, data) pair in the database.
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Like the first() method, the data return is in the format of the
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serialized format stored in the database, not in the more usable class
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object. The data should be converted to a class using the class's
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unserialize method.
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None is returned when no more data is available.
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"""
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data = self.cursor.next(*args, **kwargs)
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if data:
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return (data[0], pickle.loads(data[1]))
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return None
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def prev(self, *args, **kwargs):
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"""
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Return the previous (index, data) pair in the database.
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Like the first() method, the data return is in the format of the
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serialized format stored in the database, not in the more usable class
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object. The data should be converted to a class using the class's
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unserialize method.
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If no data is available, None is returned.
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"""
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data = self.cursor.prev(*args, **kwargs)
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if data:
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return (data[0], pickle.loads(data[1]))
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return None
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def last(self, *args, **kwargs):
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"""
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Return the last (index, data) pair in the database.
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Like the first() method, the data return is in the format of the
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serialized format stored in the database, not in the more usable class
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object. The data should be converted to a class using the class's
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unserialize method.
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None is returned when no more data is available.
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"""
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data = self.cursor.last(*args, **kwargs)
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if data:
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return (data[0], pickle.loads(data[1]))
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return None
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