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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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