serialization.py

   1 # This file is part of jack_mixer
   2 #
   3 # Copyright (C) 2006 Nedko Arnaudov <nedko@arnaudov.name>
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation; version 2 of the License
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License
  15 # along with this program; if not, write to the Free Software
  16 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17
  18 import logging
  19
  20
  21 log = logging.getLogger(__name__)
  22
  23
  24 class SerializationBackend:
  25     '''Base class for serialization backends'''
  26     def get_root_serialization_object(self, name):
  27         '''Returns serialization object where properties of root object
  28            will be serialized to'''
  29         # this method should never be called for the base class
  30         raise NotImplementedError
  31
  32     def get_child_serialization_object(self, name, backend_object):
  33         # this method should never be called for the base class
  34         raise NotImplementedError
  35
  36
  37 class SerializationObjectBackend:
  38     '''Base class for serialization backend objects where real object
  39        properties will be serialized to or unserialized from.'''
  40     def add_property(self, name, value):
  41         '''Serialize particular property'''
  42         pass
  43
  44     def get_childs(self):
  45         pass
  46
  47     def get_properties(self):
  48         pass
  49
  50     def serialization_name(self):
  51         return None
  52
  53
  54 class SerializedObject:
  55     '''Base class for object supporting serialization'''
  56     def serialization_name(self):
  57         return None
  58
  59     def serialize(self, object_backend):
  60         '''Serialize properties of called object into supplied serialization_object_backend'''
  61         pass
  62
  63     def serialization_get_childs(self):
  64         '''Get child objects tha required and support serialization'''
  65         return []
  66
  67     def unserialize_property(self, name, value):
  68         pass
  69
  70     def unserialize_child(self, name):
  71         return None
  72
  73
  74 class Serializator:
  75     def __init__(self):
  76         pass
  77
  78     def serialize(self, root, backend):
  79         self.serialize_one(backend, root, backend.get_root_serialization_object(root.serialization_name()))
  80
  81     def unserialize(self, root, backend):
  82         backend_object = backend.get_root_unserialization_object(root.serialization_name())
  83         if backend_object == None:
  84             return False
  85
  86         return self.unserialize_one(backend, root, backend_object)
  87
  88     def unserialize_one(self, backend, object, backend_object):
  89         log.debug("Unserializing %r.", object)
  90         properties = backend_object.get_properties()
  91         for name, value in properties.items():
  92             log.debug("%s = %s", name, value)
  93             if not object.unserialize_property(name, value):
  94                 return False
  95
  96         backend_childs = backend_object.get_childs()
  97         for backend_child in backend_childs:
  98             name = backend_child.serialization_name()
  99             child = object.unserialize_child(name)
 100             if not child:
 101                 return False
 102             if not self.unserialize_one(backend, child, backend_child):
 103                 return False
 104
 105         return True
 106
 107     def serialize_one(self, backend, object, backend_object):
 108         object.serialize(backend_object)
 109         childs = object.serialization_get_childs()
 110         for child in childs:
 111             log.debug("Serializing child %r.", child)
 112             self.serialize_one(backend, child,
 113                                backend.get_child_serialization_object(
 114                                        child.serialization_name(), backend_object))