1# Protocol Buffers - Google's data interchange format
2# Copyright 2008 Google Inc.  All rights reserved.
3# https://developers.google.com/protocol-buffers/
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30
31"""Provides a container for DescriptorProtos."""
32
33__author__ = 'matthewtoia@google.com (Matt Toia)'
34
35
36class Error(Exception):
37  pass
38
39
40class DescriptorDatabaseConflictingDefinitionError(Error):
41  """Raised when a proto is added with the same name & different descriptor."""
42
43
44class DescriptorDatabase(object):
45  """A container accepting FileDescriptorProtos and maps DescriptorProtos."""
46
47  def __init__(self):
48    self._file_desc_protos_by_file = {}
49    self._file_desc_protos_by_symbol = {}
50
51  def Add(self, file_desc_proto):
52    """Adds the FileDescriptorProto and its types to this database.
53
54    Args:
55      file_desc_proto: The FileDescriptorProto to add.
56    Raises:
57      DescriptorDatabaseException: if an attempt is made to add a proto
58        with the same name but different definition than an exisiting
59        proto in the database.
60    """
61    proto_name = file_desc_proto.name
62    if proto_name not in self._file_desc_protos_by_file:
63      self._file_desc_protos_by_file[proto_name] = file_desc_proto
64    elif self._file_desc_protos_by_file[proto_name] != file_desc_proto:
65      raise DescriptorDatabaseConflictingDefinitionError(
66          '%s already added, but with different descriptor.' % proto_name)
67
68    # Add the top-level Message, Enum and Extension descriptors to the index.
69    package = file_desc_proto.package
70    for message in file_desc_proto.message_type:
71      self._file_desc_protos_by_symbol.update(
72          (name, file_desc_proto) for name in _ExtractSymbols(message, package))
73    for enum in file_desc_proto.enum_type:
74      self._file_desc_protos_by_symbol[
75          '.'.join((package, enum.name))] = file_desc_proto
76    for extension in file_desc_proto.extension:
77      self._file_desc_protos_by_symbol[
78          '.'.join((package, extension.name))] = file_desc_proto
79
80  def FindFileByName(self, name):
81    """Finds the file descriptor proto by file name.
82
83    Typically the file name is a relative path ending to a .proto file. The
84    proto with the given name will have to have been added to this database
85    using the Add method or else an error will be raised.
86
87    Args:
88      name: The file name to find.
89
90    Returns:
91      The file descriptor proto matching the name.
92
93    Raises:
94      KeyError if no file by the given name was added.
95    """
96
97    return self._file_desc_protos_by_file[name]
98
99  def FindFileContainingSymbol(self, symbol):
100    """Finds the file descriptor proto containing the specified symbol.
101
102    The symbol should be a fully qualified name including the file descriptor's
103    package and any containing messages. Some examples:
104
105    'some.package.name.Message'
106    'some.package.name.Message.NestedEnum'
107
108    The file descriptor proto containing the specified symbol must be added to
109    this database using the Add method or else an error will be raised.
110
111    Args:
112      symbol: The fully qualified symbol name.
113
114    Returns:
115      The file descriptor proto containing the symbol.
116
117    Raises:
118      KeyError if no file contains the specified symbol.
119    """
120
121    return self._file_desc_protos_by_symbol[symbol]
122
123
124def _ExtractSymbols(desc_proto, package):
125  """Pulls out all the symbols from a descriptor proto.
126
127  Args:
128    desc_proto: The proto to extract symbols from.
129    package: The package containing the descriptor type.
130
131  Yields:
132    The fully qualified name found in the descriptor.
133  """
134
135  message_name = '.'.join((package, desc_proto.name))
136  yield message_name
137  for nested_type in desc_proto.nested_type:
138    for symbol in _ExtractSymbols(nested_type, message_name):
139      yield symbol
140  for enum_type in desc_proto.enum_type:
141    yield '.'.join((message_name, enum_type.name))
142