1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
# Copyright (c) 2011-2012 OpenStack, LLC.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Filter support
"""
import inspect
from stevedore import extension
class BaseFilter(object):
"""Base class for all filter classes."""
def _filter_one(self, obj, filter_properties):
"""Return True if it passes the filter, False otherwise.
Override this in a subclass.
"""
return True
def filter_all(self, filter_obj_list, filter_properties):
"""Yield objects that pass the filter.
Can be overriden in a subclass, if you need to base filtering
decisions on all objects. Otherwise, one can just override
_filter_one() to filter a single object.
"""
for obj in filter_obj_list:
if self._filter_one(obj, filter_properties):
yield obj
class BaseFilterHandler(object):
""" Base class to handle loading filter classes.
This class should be subclassed where one needs to use filters.
"""
def __init__(self, filter_class_type, filter_namespace):
self.namespace = filter_namespace
self.filter_class_type = filter_class_type
self.filter_manager = extension.ExtensionManager(filter_namespace)
def _is_correct_class(self, obj):
"""Return whether an object is a class of the correct type and
is not prefixed with an underscore.
"""
return (inspect.isclass(obj) and
not obj.__name__.startswith('_') and
issubclass(obj, self.filter_class_type))
def get_all_classes(self):
return [x.plugin for x in self.filter_manager
if self._is_correct_class(x.plugin)]
def get_filtered_objects(self, filter_classes, objs,
filter_properties):
for filter_cls in filter_classes:
objs = filter_cls().filter_all(objs, filter_properties)
return list(objs)
|
