519 lines
19 KiB
Python
519 lines
19 KiB
Python
# File: convert.py
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# Library: DOPAL - DO Python Azureus Library
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; version 2 of the License.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details ( see the COPYING file ).
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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'''
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Contains classes used to convert an XML structure back into an object
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structure.
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'''
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# We disable the override checks (subclasses of mixins are allowed to have
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# different signatures - arguments they want can be explicitly named, arguments
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# they don't want can be left unnamed in kwargs).
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#
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# We also disable the class attribute checks - converter calls a lot of methods
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# which are only defined in mixin classes.
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__pychecker__ = 'unusednames=attributes,kwargs,object_id,value,self no-override no-classattr no-objattr'
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import types
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from dopal.aztypes import is_array_type, get_component_type, \
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is_java_argument_type, is_java_return_type
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from dopal.classes import is_azureus_argument_class, is_azureus_return_class
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from dopal.errors import AbortConversion, DelayConversion, SkipConversion
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from dopal.utils import Sentinel
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ATOM_TYPE = Sentinel('atom')
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SEQUENCE_TYPE = Sentinel('sequence')
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MAPPING_TYPE = Sentinel('mapping')
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OBJECT_TYPE = Sentinel('object')
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NULL_TYPE = Sentinel('null')
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del Sentinel
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class Converter(object):
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def __call__(self, value, result_type=None):
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return self.convert(value, source_parent=None, target_parent=None,
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attribute=None, sequence_index=None, suggested_type=result_type)
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def convert(self, value, **kwargs):
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# The keyword arguments we have here include data for the reader and
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# the writer. We separate kwargs into three parts -
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# 1) Reader-only values.
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# 2) Writer-only values.
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# 3) All keyword arguments.
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reader_kwargs = kwargs.copy()
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writer_kwargs = kwargs.copy()
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convert_kwargs = kwargs
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del kwargs
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writer_kwargs['parent'] = writer_kwargs['target_parent']
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reader_kwargs['parent'] = reader_kwargs['source_parent']
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del reader_kwargs['target_parent']
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del reader_kwargs['source_parent']
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del writer_kwargs['target_parent']
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del writer_kwargs['source_parent']
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# Keyword arguments:
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# attribute
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# mapping_key
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# sequence_index
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# suggested_type
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#
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# parent (reader_kwargs and writer_kwargs, not in standard kwargs)
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# source_parent (not in reader_kwargs, not in writer_kwargs)
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# target_parent (not in reader_kwargs, not in writer_kwargs)
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conversion_type = self.categorise_object(value, **reader_kwargs)
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if conversion_type is NULL_TYPE:
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return None
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elif conversion_type is ATOM_TYPE:
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atomic_value = self.get_atomic_value(value, **reader_kwargs)
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return self.convert_atom(atomic_value, **writer_kwargs)
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elif conversion_type is SEQUENCE_TYPE:
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accepted_seq = []
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rejected_seq = []
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# The item we are currently looking at (value) is ignored.
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# It is a normal sequence which doesn't contain any useful
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# data, so we act as if each item in the sequence is
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# actually an attribute of the source object (where the
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# attribute name is taken from the attribute name of the
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# list).
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# Note - I would use enumerate, but I'm trying to leave this
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# Python 2.2 compatible.
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sequence_items = self.get_sequence_items(value, **reader_kwargs)
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for i in range(len(sequence_items)):
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item = sequence_items[i]
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this_kwargs = convert_kwargs.copy()
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this_kwargs['sequence_index'] = i
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this_kwargs['suggested_type'] = self.get_suggested_type_for_sequence_component(value, **writer_kwargs)
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try:
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sub_element = self.convert(item, **this_kwargs)
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except SkipConversion, error:
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pass
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except AbortConversion, error:
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import sys
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self.handle_error(item, error, sys.exc_info()[2])
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rejected_seq.append((item, error, sys.exc_info()[2]))
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else:
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accepted_seq.append(sub_element)
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del this_kwargs
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if rejected_seq:
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self.handle_errors(rejected_seq, accepted_seq, conversion_type)
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return self.make_sequence(accepted_seq, **writer_kwargs)
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elif conversion_type is MAPPING_TYPE:
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accepted_dict = {}
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rejected_dict = {}
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for map_key, map_value in self.get_mapping_items(value, **reader_kwargs):
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this_kwargs = convert_kwargs.copy()
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this_kwargs['mapping_key'] = map_key
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this_kwargs['suggested_type'] = self.get_suggested_type_for_mapping_component(value, **this_kwargs)
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try:
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converted_value = self.convert(map_value, **this_kwargs)
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except SkipConversion, error:
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pass
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except AbortConversion, error:
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import sys
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self.handle_error(map_value, error, sys.exc_info()[2])
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rejected_dict[map_key] = (map_value, error, sys.exc_info()[2])
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else:
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accepted_dict[map_key] = converted_value
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del this_kwargs
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if rejected_dict:
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self.handle_errors(rejected_dict, accepted_dict, conversion_type)
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return self.make_mapping(accepted_dict, **writer_kwargs)
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elif conversion_type is OBJECT_TYPE:
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object_id = self.get_object_id(value, **reader_kwargs)
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source_attributes = self.get_object_attributes(value, **reader_kwargs)
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# Try and convert the object attributes first.
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#
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# If we can't, because the parent object is requested, then
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# we'll convert that first instead.
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#
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# If the code which converts the parent object requests that
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# the attributes should be defined first, then we just exit
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# with an error - we can't have attributes requesting that the
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# object is converted first, and the object requesting attributes
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# are converted first.
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try:
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attributes = self._get_object_attributes(value, None, source_attributes)
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except DelayConversion:
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# We will allow DelayConversions which arise from this block
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# to propogate.
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new_object = self.make_object(object_id, attributes=None, **writer_kwargs)
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attributes = self._get_object_attributes(value, new_object, source_attributes)
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self.add_attributes_to_object(attributes, new_object, **writer_kwargs)
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else:
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new_object = self.make_object(object_id, attributes, **writer_kwargs)
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return new_object
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else:
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raise ValueError, "bad result from categorise_object: %s" % conversion_type
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def _get_object_attributes(self, value, parent, source_attributes):
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accepted = {}
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rejected = {}
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for attribute_name, attribute_value in source_attributes.items():
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this_kwargs = {}
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this_kwargs['source_parent'] = value
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this_kwargs['target_parent'] = parent
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this_kwargs['attribute'] = attribute_name
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this_kwargs['mapping_key'] = None
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this_kwargs['sequence_index'] = None
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this_kwargs['suggested_type'] = self.get_suggested_type_for_attribute(value=attribute_value, parent=parent,
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attribute=attribute_name,
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mapping_key=None)
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try:
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converted_value = self.convert(attribute_value, **this_kwargs)
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except SkipConversion, error:
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pass
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except AbortConversion, error:
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import sys
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self.handle_error(attribute_value, error, sys.exc_info()[2])
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rejected[attribute_name] = (attribute_value, error, sys.exc_info()[2])
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else:
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accepted[attribute_name] = converted_value
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if rejected:
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self.handle_errors(rejected, accepted, OBJECT_TYPE)
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return accepted
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def handle_errors(self, rejected, accepted, conversion_type):
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if isinstance(rejected, dict):
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error_seq = rejected.itervalues()
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else:
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error_seq = iter(rejected)
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attribute, error, traceback = error_seq.next()
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raise error, None, traceback
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def handle_error(self, object_, error, traceback):
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raise error, None, traceback
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class ReaderMixin(object):
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# Need to be implemented by subclasses:
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#
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# def categorise_object(self, value, suggested_type, **kwargs):
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# def get_object_id(self, value, **kwargs):
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# def get_object_attributes(self, value, **kwargs):
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# You can raise DelayConversion here.
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def get_atomic_value(self, value, **kwargs):
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return value
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def get_sequence_items(self, value, **kwargs):
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return value
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def get_mapping_items(self, value, **kwargs):
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return value
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class WriterMixin(object):
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# Need to be implemented by subclasses:
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#
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# def make_object(self, object_id, attributes, **kwargs):
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# You can raise DelayConversion here.
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def convert_atom(self, atomic_value, suggested_type, **kwargs):
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if suggested_type is None:
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return atomic_value
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else:
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from dopal.aztypes import unwrap_value
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return unwrap_value(atomic_value, suggested_type)
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def make_sequence(self, sequence, **kwargs):
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return sequence
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def make_mapping(self, mapping, **kwargs):
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return mapping
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def add_attributes_to_object(self, attributes, new_object, **kwargs):
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new_object.update_remote_data(attributes)
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def get_suggested_type_for_sequence_component(self, value, **kwargs):
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return None
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def get_suggested_type_for_mapping_component(self, value, **kwargs):
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return None
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def get_suggested_type_for_attribute(self, value, **kwargs):
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return None
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class XMLStructureReader(ReaderMixin):
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def categorise_object(self, node, suggested_type, **kwargs):
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from xml.dom import Node
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if node is None:
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number_of_nodes = 0
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null_value = True
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elif isinstance(node, types.StringTypes):
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number_of_nodes = -1 # Means "no-node type".
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null_value = not node
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else:
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number_of_nodes = len(node.childNodes)
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null_value = not number_of_nodes
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# This is a bit ambiguous - how on earth are we meant to determine
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# this? We'll see whether an explicit type is given here, otherwise
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# we'll have to just guess.
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if null_value:
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if suggested_type == 'mapping':
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return MAPPING_TYPE
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elif is_array_type(suggested_type):
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return SEQUENCE_TYPE
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# If the suggested type is atomic, then we inform them that
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# it is an atomic object. Some atomic types make sense with
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# no nodes (like an empty string). Some don't, of course
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# (like an integer), but never mind. It's better to inform
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# the caller code that it is an atom if the desired type is
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# an atom - otherwise for empty strings, we will get None
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# instead.
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elif is_java_return_type(suggested_type):
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# We'll assume it is just an atom. It can't be an object
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# without an object ID.
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return ATOM_TYPE
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# Oh well, let's just say it's null then.
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else:
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return NULL_TYPE
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if number_of_nodes == -1:
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return ATOM_TYPE
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if number_of_nodes == 1 and node.firstChild.nodeType == Node.TEXT_NODE:
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return ATOM_TYPE
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if number_of_nodes and node.firstChild.nodeName == 'ENTRY':
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return SEQUENCE_TYPE
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if suggested_type == 'mapping':
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return MAPPING_TYPE
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return OBJECT_TYPE
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def get_atomic_value(self, node, **kwargs):
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if node is None:
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# The only atomic type which provides an empty response are
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# string types, so we will return an empty string.
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return ''
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elif isinstance(node, types.StringTypes):
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return node
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else:
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from dopal.xmlutils import get_text_content
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return get_text_content(node)
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def get_sequence_items(self, node, **kwargs):
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if node is None:
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return []
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return node.childNodes
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def get_mapping_items(self, node, **kwargs):
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if node is None:
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return {}
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# Not actually used, but just in case...
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result_dict = {}
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for child_node in node.childNodes:
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if result_dict.has_key(child_node.nodeName):
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raise AbortConversion("duplicate attribute - " + child_node.nodeName, child_node)
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result_dict[child_node.nodeName] = child_node
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return result_dict
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def get_object_id(node, **kwargs):
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if node is None:
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return None
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for child_node in node.childNodes:
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if child_node.nodeName == '_object_id':
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from dopal.xmlutils import get_text_content
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return long(get_text_content(child_node))
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else:
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return None
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# Used by StructuredResponse.get_object_id, so we make it static.
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get_object_id = staticmethod(get_object_id)
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def get_object_attributes(self, node, **kwargs):
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result_dict = self.get_mapping_items(node, **kwargs)
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for key in result_dict.keys():
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if key.startswith('azureus_'):
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del result_dict[key]
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elif key in ['_connection_id', '_object_id']:
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del result_dict[key]
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return result_dict
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class ObjectWriterMixin(WriterMixin):
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connection = None
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# attributes may be None if not defined at this point.
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#
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# You can raise DelayConversion here.
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def make_object(self, object_id, attributes, suggested_type=None, parent=None, attribute=None, **kwargs):
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class_to_use = None
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if suggested_type is not None:
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class_to_use = self.get_class_for_object(suggested_type, attributes, parent, attribute)
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if class_to_use is None:
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class_to_use = self.get_default_class_for_object()
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if class_to_use is None:
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# - Drop the attribute.
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# - Put the attribute as is (convert it into a typeless
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# object)
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# - Raise an error.
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#
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# For now, we'll avoid creating the attribute altogether.
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#
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# Note - if the object has no parent, then that's a more
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# serious situation. We may actually be returning a blank
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# value instead of a representive object - in my opinion,
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# it is better to fail in these cases.
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#
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# A broken object (missing attributes) is more desirable than
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# having an object missing entirely if it is the actual object
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# being returned.
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if parent is None:
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cls_to_use = AbortConversion
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else:
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cls_to_use = SkipConversion
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raise cls_to_use(text="no default class defined by converter", obj=(parent, attribute, suggested_type))
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# Alternative error-based code to use:
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#
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# err_kwargs = {}
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# err_kwargs['obj'] = suggested_type
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# if parent is None:
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# if attribute is None:
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# pass
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# else:
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# err_kwargs['text'] = 'attr=' + attribute
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# else:
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# err_kwargs['text'] = "%(parent)r.%(attribute)s" %
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# locals()
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# raise InvalidRemoteClassTypeError(**err_kwargs)
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result = class_to_use(self.connection, object_id)
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if attributes is not None:
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self.add_attributes_to_object(attributes, result)
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return result
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def get_class_for_object(self, suggested_type, attributes=None, parent=None, attribute=None):
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return None
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def get_default_class_for_object(self):
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return None
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class RemoteObjectWriterMixin(ObjectWriterMixin):
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class_map = {}
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# XXX: This will need to be changed to something which will:
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# - If true, raise an error if the parent does not return an appropriate
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# type for any given attribute.
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# - If false, will never complain.
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# - If none (default), complain only when debug mode is on.
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force_attribute_types = False
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def get_class_for_object(self, suggested_type, attributes=None, parent=None, attribute=None):
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if suggested_type is None:
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return None
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return self.class_map.get(suggested_type, None)
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def get_default_class_for_object(self):
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if self.class_map.has_key(None):
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return self.class_map[None]
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_super = super(RemoteObjectWriterMixin, self)
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return _super.get_default_class_for_object()
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def get_suggested_type_for_sequence_component(self, value, suggested_type, **kwargs):
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if suggested_type is None:
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return None
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if is_array_type(suggested_type):
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return get_component_type(suggested_type)
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else:
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raise AbortConversion("parent of value is a sequence, but the suggested type is not an array type",
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obj=value)
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def _get_suggested_type_for_named_item(self, value, parent, attribute, mapping_key=None, **kwargs):
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if parent is None:
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raise DelayConversion
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result_type = None
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if hasattr(parent, '_get_type_for_attribute'):
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result_type = parent._get_type_for_attribute(attribute, mapping_key)
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if self.force_attribute_types and result_type is None:
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txt = "%(parent)r could not provide type for '%(attribute)s'"
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if mapping_key is not None:
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txt += ", [%(mapping_key)s]"
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raise AbortConversion(txt % locals())
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return result_type
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get_suggested_type_for_mapping_component = \
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get_suggested_type_for_attribute = _get_suggested_type_for_named_item
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class RemoteObjectConverter(Converter,
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XMLStructureReader, RemoteObjectWriterMixin):
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def __init__(self, connection=None):
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super(Converter, self).__init__()
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self.connection = connection
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def is_azureus_argument_type(java_type):
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return is_java_argument_type(java_type) or \
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is_azureus_argument_class(java_type)
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def is_azureus_return_type(java_type):
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return is_java_return_type(java_type) or \
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is_azureus_return_class(java_type)
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