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      1 # Protocol Buffers - Google's data interchange format
      2 # Copyright 2008 Google Inc.  All rights reserved.
      3 # http://code.google.com/p/protobuf/
      4 #
      5 # Redistribution and use in source and binary forms, with or without
      6 # modification, are permitted provided that the following conditions are
      7 # met:
      8 #
      9 #     * Redistributions of source code must retain the above copyright
     10 # notice, this list of conditions and the following disclaimer.
     11 #     * Redistributions in binary form must reproduce the above
     12 # copyright notice, this list of conditions and the following disclaimer
     13 # in the documentation and/or other materials provided with the
     14 # distribution.
     15 #     * Neither the name of Google Inc. nor the names of its
     16 # contributors may be used to endorse or promote products derived from
     17 # this software without specific prior written permission.
     18 #
     19 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     20 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     21 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     22 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     23 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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     25 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     26 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     27 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     28 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     29 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30 
     31 """Provides a factory class for generating dynamic messages."""
     32 
     33 __author__ = 'matthewtoia (at] google.com (Matt Toia)'
     34 
     35 from google.protobuf import descriptor_database
     36 from google.protobuf import descriptor_pool
     37 from google.protobuf import message
     38 from google.protobuf import reflection
     39 
     40 
     41 class MessageFactory(object):
     42   """Factory for creating Proto2 messages from descriptors in a pool."""
     43 
     44   def __init__(self):
     45     """Initializes a new factory."""
     46     self._classes = {}
     47 
     48   def GetPrototype(self, descriptor):
     49     """Builds a proto2 message class based on the passed in descriptor.
     50 
     51     Passing a descriptor with a fully qualified name matching a previous
     52     invocation will cause the same class to be returned.
     53 
     54     Args:
     55       descriptor: The descriptor to build from.
     56 
     57     Returns:
     58       A class describing the passed in descriptor.
     59     """
     60 
     61     if descriptor.full_name not in self._classes:
     62       result_class = reflection.GeneratedProtocolMessageType(
     63           descriptor.name.encode('ascii', 'ignore'),
     64           (message.Message,),
     65           {'DESCRIPTOR': descriptor})
     66       self._classes[descriptor.full_name] = result_class
     67       for field in descriptor.fields:
     68         if field.message_type:
     69           self.GetPrototype(field.message_type)
     70     return self._classes[descriptor.full_name]
     71 
     72 
     73 _DB = descriptor_database.DescriptorDatabase()
     74 _POOL = descriptor_pool.DescriptorPool(_DB)
     75 _FACTORY = MessageFactory()
     76 
     77 
     78 def GetMessages(file_protos):
     79   """Builds a dictionary of all the messages available in a set of files.
     80 
     81   Args:
     82     file_protos: A sequence of file protos to build messages out of.
     83 
     84   Returns:
     85     A dictionary containing all the message types in the files mapping the
     86     fully qualified name to a Message subclass for the descriptor.
     87   """
     88 
     89   result = {}
     90   for file_proto in file_protos:
     91     _DB.Add(file_proto)
     92   for file_proto in file_protos:
     93     for desc in _GetAllDescriptors(file_proto.message_type, file_proto.package):
     94       result[desc.full_name] = _FACTORY.GetPrototype(desc)
     95   return result
     96 
     97 
     98 def _GetAllDescriptors(desc_protos, package):
     99   """Gets all levels of nested message types as a flattened list of descriptors.
    100 
    101   Args:
    102     desc_protos: The descriptor protos to process.
    103     package: The package where the protos are defined.
    104 
    105   Yields:
    106     Each message descriptor for each nested type.
    107   """
    108 
    109   for desc_proto in desc_protos:
    110     name = '.'.join((package, desc_proto.name))
    111     yield _POOL.FindMessageTypeByName(name)
    112     for nested_desc in _GetAllDescriptors(desc_proto.nested_type, name):
    113       yield nested_desc
    114