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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, | |
24 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
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 """A database of Python protocol buffer generated symbols. | |
32 | |
33 SymbolDatabase makes it easy to create new instances of a registered type, given | |
34 only the type's protocol buffer symbol name. Once all symbols are registered, | |
35 they can be accessed using either the MessageFactory interface which | |
36 SymbolDatabase exposes, or the DescriptorPool interface of the underlying | |
37 pool. | |
38 | |
39 Example usage: | |
40 | |
41 db = symbol_database.SymbolDatabase() | |
42 | |
43 # Register symbols of interest, from one or multiple files. | |
44 db.RegisterFileDescriptor(my_proto_pb2.DESCRIPTOR) | |
45 db.RegisterMessage(my_proto_pb2.MyMessage) | |
46 db.RegisterEnumDescriptor(my_proto_pb2.MyEnum.DESCRIPTOR) | |
47 | |
48 # The database can be used as a MessageFactory, to generate types based on | |
49 # their name: | |
50 types = db.GetMessages(['my_proto.proto']) | |
51 my_message_instance = types['MyMessage']() | |
52 | |
53 # The database's underlying descriptor pool can be queried, so it's not | |
54 # necessary to know a type's filename to be able to generate it: | |
55 filename = db.pool.FindFileContainingSymbol('MyMessage') | |
56 my_message_instance = db.GetMessages([filename])['MyMessage']() | |
57 | |
58 # This functionality is also provided directly via a convenience method: | |
59 my_message_instance = db.GetSymbol('MyMessage')() | |
60 """ | |
61 | |
62 | |
63 from google.protobuf import descriptor_pool | |
64 | |
65 | |
66 class SymbolDatabase(object): | |
67 """A database of Python generated symbols. | |
68 | |
69 SymbolDatabase also models message_factory.MessageFactory. | |
70 | |
71 The symbol database can be used to keep a global registry of all protocol | |
72 buffer types used within a program. | |
73 """ | |
74 | |
75 def __init__(self): | |
76 """Constructor.""" | |
77 | |
78 self._symbols = {} | |
79 self._symbols_by_file = {} | |
80 self.pool = descriptor_pool.DescriptorPool() | |
81 | |
82 def RegisterMessage(self, message): | |
83 """Registers the given message type in the local database. | |
84 | |
85 Args: | |
86 message: a message.Message, to be registered. | |
87 | |
88 Returns: | |
89 The provided message. | |
90 """ | |
91 | |
92 desc = message.DESCRIPTOR | |
93 self._symbols[desc.full_name] = message | |
94 if desc.file.name not in self._symbols_by_file: | |
95 self._symbols_by_file[desc.file.name] = {} | |
96 self._symbols_by_file[desc.file.name][desc.full_name] = message | |
97 self.pool.AddDescriptor(desc) | |
98 return message | |
99 | |
100 def RegisterEnumDescriptor(self, enum_descriptor): | |
101 """Registers the given enum descriptor in the local database. | |
102 | |
103 Args: | |
104 enum_descriptor: a descriptor.EnumDescriptor. | |
105 | |
106 Returns: | |
107 The provided descriptor. | |
108 """ | |
109 self.pool.AddEnumDescriptor(enum_descriptor) | |
110 return enum_descriptor | |
111 | |
112 def RegisterFileDescriptor(self, file_descriptor): | |
113 """Registers the given file descriptor in the local database. | |
114 | |
115 Args: | |
116 file_descriptor: a descriptor.FileDescriptor. | |
117 | |
118 Returns: | |
119 The provided descriptor. | |
120 """ | |
121 self.pool.AddFileDescriptor(file_descriptor) | |
122 | |
123 def GetSymbol(self, symbol): | |
124 """Tries to find a symbol in the local database. | |
125 | |
126 Currently, this method only returns message.Message instances, however, if | |
127 may be extended in future to support other symbol types. | |
128 | |
129 Args: | |
130 symbol: A str, a protocol buffer symbol. | |
131 | |
132 Returns: | |
133 A Python class corresponding to the symbol. | |
134 | |
135 Raises: | |
136 KeyError: if the symbol could not be found. | |
137 """ | |
138 | |
139 return self._symbols[symbol] | |
140 | |
141 def GetPrototype(self, descriptor): | |
142 """Builds a proto2 message class based on the passed in descriptor. | |
143 | |
144 Passing a descriptor with a fully qualified name matching a previous | |
145 invocation will cause the same class to be returned. | |
146 | |
147 Args: | |
148 descriptor: The descriptor to build from. | |
149 | |
150 Returns: | |
151 A class describing the passed in descriptor. | |
152 """ | |
153 | |
154 return self.GetSymbol(descriptor.full_name) | |
155 | |
156 def GetMessages(self, files): | |
157 """Gets all the messages from a specified file. | |
158 | |
159 This will find and resolve dependencies, failing if they are not registered | |
160 in the symbol database. | |
161 | |
162 | |
163 Args: | |
164 files: The file names to extract messages from. | |
165 | |
166 Returns: | |
167 A dictionary mapping proto names to the message classes. This will include | |
168 any dependent messages as well as any messages defined in the same file as | |
169 a specified message. | |
170 | |
171 Raises: | |
172 KeyError: if a file could not be found. | |
173 """ | |
174 | |
175 result = {} | |
176 for f in files: | |
177 result.update(self._symbols_by_file[f]) | |
178 return result | |
179 | |
180 _DEFAULT = SymbolDatabase() | |
181 | |
182 | |
183 def Default(): | |
184 """Returns the default SymbolDatabase.""" | |
185 return _DEFAULT | |
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