diff src/parpg/serializers.py @ 0:1fd2201f5c36

Initial commit of parpg-core.
author M. George Hansen <technopolitica@gmail.com>
date Sat, 14 May 2011 01:12:35 -0700
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/parpg/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_