Source code for waeup.kofa.sourcefactory

## $Id: 12110 2014-12-02 06:43:10Z henrik $
## Copyright (C) 2012 Uli Fouquet & Henrik Bettermann
## 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
## 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
"""Smarter contextual sources, that can do faster containment checks.
import zc.sourcefactory.policies
from zc.sourcefactory.factories import ContextualSourceFactory
from zc.sourcefactory.source import FactoredContextualSource

[docs]class SmartFactoredContextualSource(FactoredContextualSource): """A contextual source that can be faster. Regular ContextualSources from zc.sourcefactory suffer from very expensive and slow containment checks. __contains__ is executed as a lookup over the complete set of possible values. If, however, a source could do this lookup faster, it had no chance to do that with regular ContextualSources. This source instead looks for a `contains()` method of a contextual source first and if it has one, this method is called with `value` and `context` as arguments. If a source does not provide `contains()`, the expensive default lookup method is done instead. """
[docs] def __contains__(self, value): """Check whether `value` is part of the source. If the factored source provides a `contains(value, context)` method, this method is called for faster containment checks. If not, then the getValues() method of a factored source is used to examine each single item contained in the source. """ if hasattr(self.factory, 'contains'): return self.factory.contains(self.context, value) # This is potentially expensive! return super(SmartFactoredContextualSource, self).__contains__( value)
[docs]class SmartContextualSourceFactory(ContextualSourceFactory): source_class = SmartFactoredContextualSource
[docs]class SmartBasicContextualSourceFactory( SmartContextualSourceFactory, zc.sourcefactory.policies.BasicContextualSourcePolicy): """Abstract base implementation for a basic but smart contextual source factory. These factories use any `contains(value, context)` method of factored sources to speed up containment checks. Instances of this class can be used as replacement for `zc.sourcefactory.BasicContextualSourceFactory`. If your implementation derived from :class:`SmartBasicContextualFactory` additionally provides a smart `contains()` method, you only get benefits from using this class. The basic requirements for a working `SmartBasicContextualSourceFactory` are the same as for regular ones: you have to implement a `getValues(context)` method. You can (optionally) implements a `contains(value, context)` method. """