paula.proputil/trunk/src/paula/proputil/utils.py

   1 # Copyright (c) 2008 by Florian Friesdorf
   2 #
   3 # GNU Affero General Public License (AGPL)
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU Affero General Public License as
   7 # published by the Free Software Foundation; either version 3 of the
   8 # License, or (at your option) any later version.
   9 #
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13 # GNU Affero General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU Affero General Public
  16 # License along with this program.  If not, see
  17 # <http://www.gnu.org/licenses/>.
  18 """
  19 """
  20 __author__ = "Florian Friesdorf <flo@chaoflow.net>"
  21 __docformat__ = "plaintext"
  22
  23 from BTrees import OOBTree
  24
  25 from persistent import Persistent
  26 from persistent.list import PersistentList
  27
  28 from zope.app.container.contained import Contained
  29
  30 from zope.component import queryUtility
  31 from zope.component.interfaces import IFactory
  32
  33 from zope.interface import implements
  34
  35 from paula.properties.interfaces import IPropertyProvider
  36 from paula.proputil.interfaces import IRWPropertyProviders
  37
  38
  39 class RWPropertyProviders(Persistent, Contained):
  40     """Utility delivering IPropertyProviders for principal ids
  41
  42     IPropertyProvider objects are generated by dynamic adapter lookup from
  43     IPropertyProviderAdaptable objects, which are retrieved from an internal
  44     mapping. Objects enter/leave the mapping through register/unregister.
  45
  46     Currently we do not support modification of principal id for registered
  47     objects; before doing anything that modifies the prinicipal id of an object,
  48     you need to unregister and reregister the object.
  49
  50     This utility could be registered globally and works outside of an
  51     application server. However, the adapter lookup for IPropertyProvider
  52     needs to be supported.
  53
  54
  55     Mappings are empty, for a new utility
  56
  57         >>> ppu = RWPropertyProviders()
  58         >>> len(ppu._objs)
  59         0
  60
  61     Suitable objects end up in the mapping, strings work as id
  62
  63         >>> a = Mock(id = '1')
  64         >>> alsoProvides(a, IPropertyProvider)
  65         >>> ppu.register(a)
  66         >>> len(ppu._objs['1'])
  67         1
  68         >>> ppu._objs['1'][0] is a
  69         True
  70
  71     Object with same id is appended to the same list
  72
  73         >>> b = Mock(id = '1')
  74         >>> alsoProvides(b, IPropertyProvider)
  75         >>> ppu.register(b)
  76         >>> len(ppu._objs['1'])
  77         2
  78         >>> ppu._objs['1'][0] is a
  79         True
  80         >>> ppu._objs['1'][1] is b
  81         True
  82
  83     Unsuitable object triggers TypeError
  84
  85         >>> c = Mock(id = '2')
  86         >>> ppu.register(c) # doctest: +IGNORE_EXCEPTION_DETAIL
  87         Traceback (most recent call last):
  88             blah
  89         TypeError: blah
  90
  91     Object with different id enters new list
  92
  93         >>> c = Mock(id = '2')
  94         >>> alsoProvides(c, IPropertyProvider)
  95         >>> ppu.register(c)
  96         >>> len(ppu._objs['2'])
  97         1
  98         >>> ppu._objs['2'][0] is c
  99         True
 100
 101     Objects are retrieved correctly
 102
 103         >>> ppu['1'][0] is a
 104         True
 105         >>> ppu['1'][1] is b
 106         True
 107         >>> ppu['2'][0] is c
 108         True
 109
 110     has_key is working
 111
 112         >>> ppu.has_key('1')
 113         True
 114         >>> ppu.has_key('0')
 115         False
 116
 117     in operator is working
 118
 119         >>> '1' in ppu
 120         True
 121         >>> '0' in ppu
 122         False
 123
 124     list of all keys can be given
 125
 126         >>> ppu.keys()
 127         ['1', '2']
 128
 129     len() is working and contains the number of ids, we have providers for
 130
 131         >>> len(ppu)
 132         2
 133     """
 134     implements(IRWPropertyProviders)
 135
 136     def __init__(self):
 137         """
 138         """
 139         self._objs = queryUtility(IFactory, 'OOBTree', OOBTree.OOBTree)()
 140
 141     def __contains__(self, id):
 142         return self.has_key(id)
 143
 144     def __getitem__(self, id):
 145         """retrieve IPropertyProvider list for principal id
 146         """
 147         pps = [IPropertyProvider(x) for x in self._objs[id]]
 148         return pps
 149
 150     def __len__(self):
 151         return self._objs.__len__()
 152
 153     def has_key(self, id):
 154         # I currently consider this a broken BTree
 155         return bool(self._objs.has_key(id))
 156
 157     def keys(self):
 158         # I currently consider this a broken BTree
 159         return list(self._objs.keys())
 160
 161     def register(self, obj):
 162         """Register an object.
 163
 164         It is assumed that an adapter lookup for IPropertyProvider succeeds.
 165         """
 166         id = IPropertyProvider(obj).id
 167         try:
 168             objs = self._objs[id]
 169         except KeyError:
 170             self._objs[id] = PersistentList()
 171             objs = self._objs[id]
 172         else:
 173             if obj in objs:
 174                 return
 175         self._objs[id].append(obj)
 176
 177     def unregister(self, obj):
 178         """Unregister an object.
 179
 180         Fails with ValueError, if the object is not registered.
 181         """
 182         id = IPropertyProvider(obj).id
 183         self._objs[id].remove(obj)