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R3596/Pyblio/Stores/resultset.py
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resultset.py
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# This file is part of pybliographer
#
# Copyright (C) 1998-2006 Frederic GOBRY
# Email : gobry@pybliographer.org
#
# This program 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 2
# of the License, or (at your option) any later version.
#
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
"""
Common implementation of in-memory result sets and views.
The result sets use a Pyblio.Arrays.KeyArray to store their
content. Views are implemented with plain lists of keys.
"""
from Pyblio import Store, Callback, Arrays, Sort
class ResultSet(Store.ResultSet, Callback.Publisher):
def __init__(self, rsid, db, contents=None):
Callback.Publisher.__init__ (self)
if contents is None:
self._contents = Arrays.KeyArray()
else:
self._contents = contents
self.id = rsid
self.name = None
self._db = db
self._db.register('delete-item', self._on_db_delete)
self._db.register('update-item', self._on_db_update)
def view (self, criterion):
return View(self, criterion)
def add(self, k):
self._contents.add(k)
self.emit('add-item', k)
return
def __delitem__(self, k):
del self._contents[k]
self.emit ('delete-item', k)
return
def itervalues (self):
for k in self._contents:
yield self._db[k]
def iteritems (self):
for k in self._contents:
yield (k, self._db[k])
def iterkeys(self):
return iter(self._contents)
__iter__ = iterkeys
def __len__(self):
return len(self._contents)
def destroy(self):
for k in list(self._contents):
del self._db[k]
def _from_array(self, contents):
self._contents = contents
def _on_db_delete (self, k):
""" invoked when the database removes an item """
try:
del self[k]
except IndexError:
pass
def _on_db_update(self, k):
if k in self._contents:
self.emit('update-item', k)
# This class could certainly benefit from optimisations: when changing
# a single value, the full list of results is recomputed every time.
class View(Callback.Publisher):
def __init__ (self, src, crit):
Callback.Publisher.__init__(self)
self._crit = crit
self._src = src
self._update(None, '')
self._src.register('add-item', self._update, 'add-item')
self._src.register('delete-item', self._update, 'delete-item')
self._src.register('update-item', self._update, 'update-item')
return
def _update(self, key, signal):
view = [(self._crit.cmp_key(e), e.key) for e in self._src.itervalues()]
view.sort(lambda a, b: Sort.compare(a[0], b[0]))
self._view = [x[1] for x in view]
self.emit(signal, key)
return
def __len__ (self):
return len(self._view)
def __getitem__ (self, i):
return self._view[i]
def __iter__ (self):
return iter (self._view)
def iterkeys (self):
return iter(self._view)
def iteritems(self):
for i in self._view:
yield (i, self._src._db[i])
def itervalues(self):
for i in self._view:
yield self._src._db[i]
def index(self, key):
try:
return self._view.index(key)
except ValueError:
raise KeyError(key)
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