diff options
Diffstat (limited to 'python/google/protobuf/internal/decoder.py')
-rwxr-xr-x | python/google/protobuf/internal/decoder.py | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/python/google/protobuf/internal/decoder.py b/python/google/protobuf/internal/decoder.py index 0f500606..3837eaea 100755 --- a/python/google/protobuf/internal/decoder.py +++ b/python/google/protobuf/internal/decoder.py @@ -733,6 +733,50 @@ def MessageSetItemDecoder(extensions_by_number): return DecodeItem # -------------------------------------------------------------------- + +def MapDecoder(field_descriptor, new_default, is_message_map): + """Returns a decoder for a map field.""" + + key = field_descriptor + tag_bytes = encoder.TagBytes(field_descriptor.number, + wire_format.WIRETYPE_LENGTH_DELIMITED) + tag_len = len(tag_bytes) + local_DecodeVarint = _DecodeVarint + # Can't read _concrete_class yet; might not be initialized. + message_type = field_descriptor.message_type + + def DecodeMap(buffer, pos, end, message, field_dict): + submsg = message_type._concrete_class() + value = field_dict.get(key) + if value is None: + value = field_dict.setdefault(key, new_default(message)) + while 1: + # Read length. + (size, pos) = local_DecodeVarint(buffer, pos) + new_pos = pos + size + if new_pos > end: + raise _DecodeError('Truncated message.') + # Read sub-message. + submsg.Clear() + if submsg._InternalParse(buffer, pos, new_pos) != new_pos: + # The only reason _InternalParse would return early is if it + # encountered an end-group tag. + raise _DecodeError('Unexpected end-group tag.') + + if is_message_map: + value[submsg.key].MergeFrom(submsg.value) + else: + value[submsg.key] = submsg.value + + # Predict that the next tag is another copy of the same repeated field. + pos = new_pos + tag_len + if buffer[new_pos:pos] != tag_bytes or new_pos == end: + # Prediction failed. Return. + return new_pos + + return DecodeMap + +# -------------------------------------------------------------------- # Optimization is not as heavy here because calls to SkipField() are rare, # except for handling end-group tags. |