Mercurial > parpg-source
diff serializers.py @ 0:7a89ea5404b1
Initial commit of parpg-core.
author | M. George Hansen <technopolitica@gmail.com> |
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date | Sat, 14 May 2011 01:12:35 -0700 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/serializers.py Sat May 14 01:12:35 2011 -0700 @@ -0,0 +1,156 @@ +# This file is part of PARPG. + +# PARPG 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 3 of the License, or +# (at your option) any later version. + +# PARPG 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 PARPG. If not, see <http://www.gnu.org/licenses/>. +""" +Provides classes used to serialize and deserialize Python classes. +""" + +from abc import ABCMeta, abstractmethod +try: + from xml.etree import cElementTree as ElementTree +except ImportError: + from xml.etree import ElementTree +try: + from collections import OrderedDict +except ImportError: + from .common.ordereddict import OrderedDict + +from .common.utils import dedent_chomp + +import logging + +logger = logging.getLogger('serializers') + +class Serializable(object): + def __init__(self, class_, init_args=None, attributes=None): + self.class_ = class_ + if init_args is not None: + self.init_args = OrderedDict(init_args) + else: + self.init_args = OrderedDict() + if attributes is not None: + self.attributes = OrderedDict(attributes) + else: + self.attributes = OrderedDict() + + +class SerializableRegistry(object): + """ + Class holding the data used to serialize and deserialize a particular + Python object. + """ + registered_classes = {} + + @classmethod + def registerClass(cls, name, class_, init_args=None, attributes=None): + serializable = Serializable(class_, init_args, attributes) + cls.registered_classes[name] = serializable + + +class AbstractSerializer(object): + __metaclass__ = ABCMeta + + @abstractmethod + def serialize(self, object_, stream): + pass + + @abstractmethod + def deserialize(self, stream): + pass + + +class XmlSerializer(AbstractSerializer): + def serialize(self, statistic, stream): + pass + + @classmethod + def deserialize(cls, stream): + element_tree = ElementTree.parse(stream) + root_element = element_tree.getroot() + object_ = cls.construct_object(root_element) + return object_ + + @classmethod + def construct_object(cls, element): + element_name = element.tag + if element_name in SerializableRegistry.registered_classes.keys(): + object_ = cls.construct_registered_class(element) + elif len(element) > 0: + # Element contains subelements, so we'll treat it as an + # OrderedDict. + if element_name == 'list': + object_ = cls.construct_list(element) + else: + object_ = cls.construct_ordered_dict(element) + else: + object_ = cls.construct_primitive(element) + return object_ + + @classmethod + def construct_registered_class(cls, element): + element_name = element.tag + serializable = SerializableRegistry.registered_classes[element_name] + class_ = serializable.class_ + init_args = OrderedDict() + for subelement in element: + arg = cls.construct_object(subelement) + subelement_name = subelement.tag + init_args[subelement_name] = arg + try: + object_ = class_(**init_args) + except (TypeError, ValueError) as exception: + logger.error(init_args) + error_message = \ + 'unable to deserialize tag {0}: {1}'.format(element_name, + exception) + raise ValueError(error_message) + return object_ + + @classmethod + def construct_ordered_dict(cls, element): + object_ = OrderedDict() + for subelement in element: + child = cls.construct_object(subelement) + name = subelement.tag + object_[name] = child + return object_ + + @classmethod + def construct_list(cls, element): + object_ = [] + for subelement in element: + child = cls.construct_object(subelement) + object_.append(child) + return object_ + + @classmethod + def construct_primitive(cls, element): + text = element.text + # Interpret the element's text as unicode by default. + element_type = element.attrib.get('type', 'unicode') + if element_type == 'unicode': + formatted_text = dedent_chomp(text) + object_ = unicode(formatted_text) + elif element_type == 'str': + formatted_text = dedent_chomp(text) + object_ = str(formatted_text) + elif element_type == 'int': + object_ = int(text) + elif element_type == 'float': + object_ = float(text) + else: + error_message = '{0!r} is not a recognized primitive type' + error_message.format(element_type) + raise ValueError(error_message) + return object_