| #!/usr/bin/env python |
| # |
| # Copyright 2007 Google Inc. |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| # |
| |
| |
| |
| |
| """Code for decoding protocol buffer primitives. |
| |
| This code is very similar to encoder.py -- read the docs for that module first. |
| |
| A "decoder" is a function with the signature: |
| Decode(buffer, pos, end, message, field_dict) |
| The arguments are: |
| buffer: The string containing the encoded message. |
| pos: The current position in the string. |
| end: The position in the string where the current message ends. May be |
| less than len(buffer) if we're reading a sub-message. |
| message: The message object into which we're parsing. |
| field_dict: message._fields (avoids a hashtable lookup). |
| The decoder reads the field and stores it into field_dict, returning the new |
| buffer position. A decoder for a repeated field may proactively decode all of |
| the elements of that field, if they appear consecutively. |
| |
| Note that decoders may throw any of the following: |
| IndexError: Indicates a truncated message. |
| struct.error: Unpacking of a fixed-width field failed. |
| message.DecodeError: Other errors. |
| |
| Decoders are expected to raise an exception if they are called with pos > end. |
| This allows callers to be lax about bounds checking: it's fineto read past |
| "end" as long as you are sure that someone else will notice and throw an |
| exception later on. |
| |
| Something up the call stack is expected to catch IndexError and struct.error |
| and convert them to message.DecodeError. |
| |
| Decoders are constructed using decoder constructors with the signature: |
| MakeDecoder(field_number, is_repeated, is_packed, key, new_default) |
| The arguments are: |
| field_number: The field number of the field we want to decode. |
| is_repeated: Is the field a repeated field? (bool) |
| is_packed: Is the field a packed field? (bool) |
| key: The key to use when looking up the field within field_dict. |
| (This is actually the FieldDescriptor but nothing in this |
| file should depend on that.) |
| new_default: A function which takes a message object as a parameter and |
| returns a new instance of the default value for this field. |
| (This is called for repeated fields and sub-messages, when an |
| instance does not already exist.) |
| |
| As with encoders, we define a decoder constructor for every type of field. |
| Then, for every field of every message class we construct an actual decoder. |
| That decoder goes into a dict indexed by tag, so when we decode a message |
| we repeatedly read a tag, look up the corresponding decoder, and invoke it. |
| """ |
| |
| |
| import struct |
| import sys |
| _PY2 = sys.version_info[0] < 3 |
| from google.net.proto2.python.internal import encoder |
| from google.net.proto2.python.internal import wire_format |
| from google.net.proto2.python.public import message |
| |
| |
| |
| |
| _POS_INF = 1e10000 |
| _NEG_INF = -_POS_INF |
| _NAN = _POS_INF * 0 |
| |
| |
| |
| |
| _DecodeError = message.DecodeError |
| |
| |
| def _VarintDecoder(mask, result_type): |
| """Return an encoder for a basic varint value (does not include tag). |
| |
| Decoded values will be bitwise-anded with the given mask before being |
| returned, e.g. to limit them to 32 bits. The returned decoder does not |
| take the usual "end" parameter -- the caller is expected to do bounds checking |
| after the fact (often the caller can defer such checking until later). The |
| decoder returns a (value, new_pos) pair. |
| """ |
| |
| local_ord = ord |
| py2 = _PY2 |
| |
| def DecodeVarint(buffer, pos): |
| result = 0 |
| shift = 0 |
| while 1: |
| b = local_ord(buffer[pos]) if py2 else buffer[pos] |
| result |= ((b & 0x7f) << shift) |
| pos += 1 |
| if not (b & 0x80): |
| result &= mask |
| result = result_type(result) |
| return (result, pos) |
| shift += 7 |
| if shift >= 64: |
| raise _DecodeError('Too many bytes when decoding varint.') |
| return DecodeVarint |
| |
| |
| def _SignedVarintDecoder(mask, result_type): |
| """Like _VarintDecoder() but decodes signed values.""" |
| |
| local_ord = ord |
| py2 = _PY2 |
| |
| def DecodeVarint(buffer, pos): |
| result = 0 |
| shift = 0 |
| while 1: |
| b = local_ord(buffer[pos]) if py2 else buffer[pos] |
| result |= ((b & 0x7f) << shift) |
| pos += 1 |
| if not (b & 0x80): |
| if result > 0x7fffffffffffffff: |
| result -= (1 << 64) |
| result |= ~mask |
| else: |
| result &= mask |
| result = result_type(result) |
| return (result, pos) |
| shift += 7 |
| if shift >= 64: |
| raise _DecodeError('Too many bytes when decoding varint.') |
| return DecodeVarint |
| |
| |
| |
| |
| |
| _DecodeVarint = _VarintDecoder((1 << 64) - 1, long) |
| _DecodeSignedVarint = _SignedVarintDecoder((1 << 64) - 1, long) |
| |
| |
| _DecodeVarint32 = _VarintDecoder((1 << 32) - 1, int) |
| _DecodeSignedVarint32 = _SignedVarintDecoder((1 << 32) - 1, int) |
| |
| |
| def ReadTag(buffer, pos): |
| """Read a tag from the buffer, and return a (tag_bytes, new_pos) tuple. |
| |
| We return the raw bytes of the tag rather than decoding them. The raw |
| bytes can then be used to look up the proper decoder. This effectively allows |
| us to trade some work that would be done in pure-python (decoding a varint) |
| for work that is done in C (searching for a byte string in a hash table). |
| In a low-level language it would be much cheaper to decode the varint and |
| use that, but not in Python. |
| """ |
| |
| py2 = _PY2 |
| |
| start = pos |
| while (ord(buffer[pos]) if py2 else buffer[pos]) & 0x80: |
| pos += 1 |
| pos += 1 |
| return (buffer[start:pos], pos) |
| |
| |
| |
| |
| |
| def _SimpleDecoder(wire_type, decode_value): |
| """Return a constructor for a decoder for fields of a particular type. |
| |
| Args: |
| wire_type: The field's wire type. |
| decode_value: A function which decodes an individual value, e.g. |
| _DecodeVarint() |
| """ |
| |
| def SpecificDecoder(field_number, is_repeated, is_packed, key, new_default): |
| if is_packed: |
| local_DecodeVarint = _DecodeVarint |
| def DecodePackedField(buffer, pos, end, message, field_dict): |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| (endpoint, pos) = local_DecodeVarint(buffer, pos) |
| endpoint += pos |
| if endpoint > end: |
| raise _DecodeError('Truncated message.') |
| while pos < endpoint: |
| (element, pos) = decode_value(buffer, pos) |
| value.append(element) |
| if pos > endpoint: |
| del value[-1] |
| raise _DecodeError('Packed element was truncated.') |
| return pos |
| return DecodePackedField |
| elif is_repeated: |
| tag_bytes = encoder.TagBytes(field_number, wire_type) |
| tag_len = len(tag_bytes) |
| def DecodeRepeatedField(buffer, pos, end, message, field_dict): |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| while 1: |
| (element, new_pos) = decode_value(buffer, pos) |
| value.append(element) |
| |
| |
| pos = new_pos + tag_len |
| if buffer[new_pos:pos] != tag_bytes or new_pos >= end: |
| |
| if new_pos > end: |
| raise _DecodeError('Truncated message.') |
| return new_pos |
| return DecodeRepeatedField |
| else: |
| def DecodeField(buffer, pos, end, message, field_dict): |
| (field_dict[key], pos) = decode_value(buffer, pos) |
| if pos > end: |
| del field_dict[key] |
| raise _DecodeError('Truncated message.') |
| return pos |
| return DecodeField |
| |
| return SpecificDecoder |
| |
| |
| def _ModifiedDecoder(wire_type, decode_value, modify_value): |
| """Like SimpleDecoder but additionally invokes modify_value on every value |
| before storing it. Usually modify_value is ZigZagDecode. |
| """ |
| |
| |
| |
| |
| def InnerDecode(buffer, pos): |
| (result, new_pos) = decode_value(buffer, pos) |
| return (modify_value(result), new_pos) |
| return _SimpleDecoder(wire_type, InnerDecode) |
| |
| |
| def _StructPackDecoder(wire_type, format): |
| """Return a constructor for a decoder for a fixed-width field. |
| |
| Args: |
| wire_type: The field's wire type. |
| format: The format string to pass to struct.unpack(). |
| """ |
| |
| value_size = struct.calcsize(format) |
| local_unpack = struct.unpack |
| |
| |
| |
| |
| |
| |
| |
| |
| def InnerDecode(buffer, pos): |
| new_pos = pos + value_size |
| result = local_unpack(format, buffer[pos:new_pos])[0] |
| return (result, new_pos) |
| return _SimpleDecoder(wire_type, InnerDecode) |
| |
| |
| def _FloatDecoder(): |
| """Returns a decoder for a float field. |
| |
| This code works around a bug in struct.unpack for non-finite 32-bit |
| floating-point values. |
| """ |
| |
| local_unpack = struct.unpack |
| b = (lambda x:x) if _PY2 else lambda x:x.encode('latin1') |
| |
| def InnerDecode(buffer, pos): |
| |
| |
| new_pos = pos + 4 |
| float_bytes = buffer[pos:new_pos] |
| |
| |
| |
| |
| if ((float_bytes[3:4] in b('\x7F\xFF')) |
| |
| and (float_bytes[2:3] >= b('\x80'))): |
| |
| |
| if float_bytes[0:3] != b('\x00\x00\x80'): |
| |
| return (_NAN, new_pos) |
| |
| if float_bytes[3:4] == b('\xFF'): |
| |
| return (_NEG_INF, new_pos) |
| return (_POS_INF, new_pos) |
| |
| |
| |
| |
| result = local_unpack('<f', float_bytes)[0] |
| return (result, new_pos) |
| return _SimpleDecoder(wire_format.WIRETYPE_FIXED32, InnerDecode) |
| |
| |
| def _DoubleDecoder(): |
| """Returns a decoder for a double field. |
| |
| This code works around a bug in struct.unpack for not-a-number. |
| """ |
| |
| local_unpack = struct.unpack |
| b = (lambda x:x) if _PY2 else lambda x:x.encode('latin1') |
| |
| def InnerDecode(buffer, pos): |
| |
| |
| new_pos = pos + 8 |
| double_bytes = buffer[pos:new_pos] |
| |
| |
| |
| |
| |
| |
| |
| if ((double_bytes[7:8] in b('\x7F\xFF')) |
| and (double_bytes[6:7] >= b('\xF0')) |
| and (double_bytes[0:7] != b('\x00\x00\x00\x00\x00\x00\xF0'))): |
| return (_NAN, new_pos) |
| |
| |
| |
| |
| result = local_unpack('<d', double_bytes)[0] |
| return (result, new_pos) |
| return _SimpleDecoder(wire_format.WIRETYPE_FIXED64, InnerDecode) |
| |
| |
| def EnumDecoder(field_number, is_repeated, is_packed, key, new_default): |
| enum_type = key.enum_type |
| if is_packed: |
| local_DecodeVarint = _DecodeVarint |
| def DecodePackedField(buffer, pos, end, message, field_dict): |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| (endpoint, pos) = local_DecodeVarint(buffer, pos) |
| endpoint += pos |
| if endpoint > end: |
| raise _DecodeError('Truncated message.') |
| while pos < endpoint: |
| value_start_pos = pos |
| (element, pos) = _DecodeSignedVarint32(buffer, pos) |
| if element in enum_type.values_by_number: |
| value.append(element) |
| else: |
| if not message._unknown_fields: |
| message._unknown_fields = [] |
| tag_bytes = encoder.TagBytes(field_number, |
| wire_format.WIRETYPE_VARINT) |
| message._unknown_fields.append( |
| (tag_bytes, buffer[value_start_pos:pos])) |
| if pos > endpoint: |
| if element in enum_type.values_by_number: |
| del value[-1] |
| else: |
| del message._unknown_fields[-1] |
| raise _DecodeError('Packed element was truncated.') |
| return pos |
| return DecodePackedField |
| elif is_repeated: |
| tag_bytes = encoder.TagBytes(field_number, wire_format.WIRETYPE_VARINT) |
| tag_len = len(tag_bytes) |
| def DecodeRepeatedField(buffer, pos, end, message, field_dict): |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| while 1: |
| (element, new_pos) = _DecodeSignedVarint32(buffer, pos) |
| if element in enum_type.values_by_number: |
| value.append(element) |
| else: |
| if not message._unknown_fields: |
| message._unknown_fields = [] |
| message._unknown_fields.append( |
| (tag_bytes, buffer[pos:new_pos])) |
| |
| |
| pos = new_pos + tag_len |
| if buffer[new_pos:pos] != tag_bytes or new_pos >= end: |
| |
| if new_pos > end: |
| raise _DecodeError('Truncated message.') |
| return new_pos |
| return DecodeRepeatedField |
| else: |
| def DecodeField(buffer, pos, end, message, field_dict): |
| value_start_pos = pos |
| (enum_value, pos) = _DecodeSignedVarint32(buffer, pos) |
| if pos > end: |
| raise _DecodeError('Truncated message.') |
| if enum_value in enum_type.values_by_number: |
| field_dict[key] = enum_value |
| else: |
| if not message._unknown_fields: |
| message._unknown_fields = [] |
| tag_bytes = encoder.TagBytes(field_number, |
| wire_format.WIRETYPE_VARINT) |
| message._unknown_fields.append( |
| (tag_bytes, buffer[value_start_pos:pos])) |
| return pos |
| return DecodeField |
| |
| |
| |
| |
| |
| Int32Decoder = _SimpleDecoder( |
| wire_format.WIRETYPE_VARINT, _DecodeSignedVarint32) |
| |
| Int64Decoder = _SimpleDecoder( |
| wire_format.WIRETYPE_VARINT, _DecodeSignedVarint) |
| |
| UInt32Decoder = _SimpleDecoder(wire_format.WIRETYPE_VARINT, _DecodeVarint32) |
| UInt64Decoder = _SimpleDecoder(wire_format.WIRETYPE_VARINT, _DecodeVarint) |
| |
| SInt32Decoder = _ModifiedDecoder( |
| wire_format.WIRETYPE_VARINT, _DecodeVarint32, wire_format.ZigZagDecode) |
| SInt64Decoder = _ModifiedDecoder( |
| wire_format.WIRETYPE_VARINT, _DecodeVarint, wire_format.ZigZagDecode) |
| |
| |
| |
| |
| |
| Fixed32Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED32, '<I') |
| Fixed64Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED64, '<Q') |
| SFixed32Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED32, '<i') |
| SFixed64Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED64, '<q') |
| FloatDecoder = _FloatDecoder() |
| DoubleDecoder = _DoubleDecoder() |
| |
| BoolDecoder = _ModifiedDecoder( |
| wire_format.WIRETYPE_VARINT, _DecodeVarint, bool) |
| |
| |
| def StringDecoder(field_number, is_repeated, is_packed, key, new_default): |
| """Returns a decoder for a string field.""" |
| |
| local_DecodeVarint = _DecodeVarint |
| local_unicode = unicode |
| |
| def _ConvertToUnicode(byte_str): |
| try: |
| return local_unicode(byte_str, 'utf-8') |
| except UnicodeDecodeError, e: |
| |
| e.reason = '%s in field: %s' % (e, key.full_name) |
| raise |
| |
| assert not is_packed |
| if is_repeated: |
| tag_bytes = encoder.TagBytes(field_number, |
| wire_format.WIRETYPE_LENGTH_DELIMITED) |
| tag_len = len(tag_bytes) |
| def DecodeRepeatedField(buffer, pos, end, message, field_dict): |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| while 1: |
| (size, pos) = local_DecodeVarint(buffer, pos) |
| new_pos = pos + size |
| if new_pos > end: |
| raise _DecodeError('Truncated string.') |
| value.append(_ConvertToUnicode(buffer[pos:new_pos])) |
| |
| pos = new_pos + tag_len |
| if buffer[new_pos:pos] != tag_bytes or new_pos == end: |
| |
| return new_pos |
| return DecodeRepeatedField |
| else: |
| def DecodeField(buffer, pos, end, message, field_dict): |
| (size, pos) = local_DecodeVarint(buffer, pos) |
| new_pos = pos + size |
| if new_pos > end: |
| raise _DecodeError('Truncated string.') |
| field_dict[key] = _ConvertToUnicode(buffer[pos:new_pos]) |
| return new_pos |
| return DecodeField |
| |
| |
| def BytesDecoder(field_number, is_repeated, is_packed, key, new_default): |
| """Returns a decoder for a bytes field.""" |
| |
| local_DecodeVarint = _DecodeVarint |
| |
| assert not is_packed |
| if is_repeated: |
| tag_bytes = encoder.TagBytes(field_number, |
| wire_format.WIRETYPE_LENGTH_DELIMITED) |
| tag_len = len(tag_bytes) |
| def DecodeRepeatedField(buffer, pos, end, message, field_dict): |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| while 1: |
| (size, pos) = local_DecodeVarint(buffer, pos) |
| new_pos = pos + size |
| if new_pos > end: |
| raise _DecodeError('Truncated string.') |
| value.append(buffer[pos:new_pos]) |
| |
| pos = new_pos + tag_len |
| if buffer[new_pos:pos] != tag_bytes or new_pos == end: |
| |
| return new_pos |
| return DecodeRepeatedField |
| else: |
| def DecodeField(buffer, pos, end, message, field_dict): |
| (size, pos) = local_DecodeVarint(buffer, pos) |
| new_pos = pos + size |
| if new_pos > end: |
| raise _DecodeError('Truncated string.') |
| field_dict[key] = buffer[pos:new_pos] |
| return new_pos |
| return DecodeField |
| |
| |
| def GroupDecoder(field_number, is_repeated, is_packed, key, new_default): |
| """Returns a decoder for a group field.""" |
| |
| end_tag_bytes = encoder.TagBytes(field_number, |
| wire_format.WIRETYPE_END_GROUP) |
| end_tag_len = len(end_tag_bytes) |
| |
| assert not is_packed |
| if is_repeated: |
| tag_bytes = encoder.TagBytes(field_number, |
| wire_format.WIRETYPE_START_GROUP) |
| tag_len = len(tag_bytes) |
| def DecodeRepeatedField(buffer, pos, end, message, field_dict): |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| while 1: |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| |
| pos = value.add()._InternalParse(buffer, pos, end) |
| |
| new_pos = pos+end_tag_len |
| if buffer[pos:new_pos] != end_tag_bytes or new_pos > end: |
| raise _DecodeError('Missing group end tag.') |
| |
| pos = new_pos + tag_len |
| if buffer[new_pos:pos] != tag_bytes or new_pos == end: |
| |
| return new_pos |
| return DecodeRepeatedField |
| else: |
| def DecodeField(buffer, pos, end, message, field_dict): |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| |
| pos = value._InternalParse(buffer, pos, end) |
| |
| new_pos = pos+end_tag_len |
| if buffer[pos:new_pos] != end_tag_bytes or new_pos > end: |
| raise _DecodeError('Missing group end tag.') |
| return new_pos |
| return DecodeField |
| |
| |
| def MessageDecoder(field_number, is_repeated, is_packed, key, new_default): |
| """Returns a decoder for a message field.""" |
| |
| local_DecodeVarint = _DecodeVarint |
| |
| assert not is_packed |
| if is_repeated: |
| tag_bytes = encoder.TagBytes(field_number, |
| wire_format.WIRETYPE_LENGTH_DELIMITED) |
| tag_len = len(tag_bytes) |
| def DecodeRepeatedField(buffer, pos, end, message, field_dict): |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| while 1: |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| |
| (size, pos) = local_DecodeVarint(buffer, pos) |
| new_pos = pos + size |
| if new_pos > end: |
| raise _DecodeError('Truncated message.') |
| |
| if value.add()._InternalParse(buffer, pos, new_pos) != new_pos: |
| |
| |
| raise _DecodeError('Unexpected end-group tag.') |
| |
| pos = new_pos + tag_len |
| if buffer[new_pos:pos] != tag_bytes or new_pos == end: |
| |
| return new_pos |
| return DecodeRepeatedField |
| else: |
| def DecodeField(buffer, pos, end, message, field_dict): |
| value = field_dict.get(key) |
| if value is None: |
| value = field_dict.setdefault(key, new_default(message)) |
| |
| (size, pos) = local_DecodeVarint(buffer, pos) |
| new_pos = pos + size |
| if new_pos > end: |
| raise _DecodeError('Truncated message.') |
| |
| if value._InternalParse(buffer, pos, new_pos) != new_pos: |
| |
| |
| raise _DecodeError('Unexpected end-group tag.') |
| return new_pos |
| return DecodeField |
| |
| |
| |
| |
| MESSAGE_SET_ITEM_TAG = encoder.TagBytes(1, wire_format.WIRETYPE_START_GROUP) |
| |
| def MessageSetItemDecoder(extensions_by_number): |
| """Returns a decoder for a MessageSet item. |
| |
| The parameter is the _extensions_by_number map for the message class. |
| |
| The message set message looks like this: |
| message MessageSet { |
| repeated group Item = 1 { |
| required int32 type_id = 2; |
| required string message = 3; |
| } |
| } |
| """ |
| |
| type_id_tag_bytes = encoder.TagBytes(2, wire_format.WIRETYPE_VARINT) |
| message_tag_bytes = encoder.TagBytes(3, wire_format.WIRETYPE_LENGTH_DELIMITED) |
| item_end_tag_bytes = encoder.TagBytes(1, wire_format.WIRETYPE_END_GROUP) |
| |
| local_ReadTag = ReadTag |
| local_DecodeVarint = _DecodeVarint |
| local_SkipField = SkipField |
| |
| def DecodeItem(buffer, pos, end, message, field_dict): |
| message_set_item_start = pos |
| type_id = -1 |
| message_start = -1 |
| message_end = -1 |
| |
| |
| |
| while 1: |
| (tag_bytes, pos) = local_ReadTag(buffer, pos) |
| if tag_bytes == type_id_tag_bytes: |
| (type_id, pos) = local_DecodeVarint(buffer, pos) |
| elif tag_bytes == message_tag_bytes: |
| (size, message_start) = local_DecodeVarint(buffer, pos) |
| pos = message_end = message_start + size |
| elif tag_bytes == item_end_tag_bytes: |
| break |
| else: |
| pos = SkipField(buffer, pos, end, tag_bytes) |
| if pos == -1: |
| raise _DecodeError('Missing group end tag.') |
| |
| if pos > end: |
| raise _DecodeError('Truncated message.') |
| |
| if type_id == -1: |
| raise _DecodeError('MessageSet item missing type_id.') |
| if message_start == -1: |
| raise _DecodeError('MessageSet item missing message.') |
| |
| extension = extensions_by_number.get(type_id) |
| if extension is not None: |
| value = field_dict.get(extension) |
| if value is None: |
| value = field_dict.setdefault( |
| extension, extension.message_type._concrete_class()) |
| if value._InternalParse(buffer, message_start,message_end) != message_end: |
| |
| |
| raise _DecodeError('Unexpected end-group tag.') |
| else: |
| if not message._unknown_fields: |
| message._unknown_fields = [] |
| message._unknown_fields.append((MESSAGE_SET_ITEM_TAG, |
| buffer[message_set_item_start:pos])) |
| |
| return pos |
| |
| return DecodeItem |
| |
| |
| |
| |
| |
| def _SkipVarint(buffer, pos, end): |
| """Skip a varint value. Returns the new position.""" |
| |
| |
| |
| while ord(buffer[pos:pos+1]) & 0x80: |
| pos += 1 |
| pos += 1 |
| if pos > end: |
| raise _DecodeError('Truncated message.') |
| return pos |
| |
| def _SkipFixed64(buffer, pos, end): |
| """Skip a fixed64 value. Returns the new position.""" |
| |
| pos += 8 |
| if pos > end: |
| raise _DecodeError('Truncated message.') |
| return pos |
| |
| def _SkipLengthDelimited(buffer, pos, end): |
| """Skip a length-delimited value. Returns the new position.""" |
| |
| (size, pos) = _DecodeVarint(buffer, pos) |
| pos += size |
| if pos > end: |
| raise _DecodeError('Truncated message.') |
| return pos |
| |
| def _SkipGroup(buffer, pos, end): |
| """Skip sub-group. Returns the new position.""" |
| |
| while 1: |
| (tag_bytes, pos) = ReadTag(buffer, pos) |
| new_pos = SkipField(buffer, pos, end, tag_bytes) |
| if new_pos == -1: |
| return pos |
| pos = new_pos |
| |
| def _EndGroup(buffer, pos, end): |
| """Skipping an END_GROUP tag returns -1 to tell the parent loop to break.""" |
| |
| return -1 |
| |
| def _SkipFixed32(buffer, pos, end): |
| """Skip a fixed32 value. Returns the new position.""" |
| |
| pos += 4 |
| if pos > end: |
| raise _DecodeError('Truncated message.') |
| return pos |
| |
| def _RaiseInvalidWireType(buffer, pos, end): |
| """Skip function for unknown wire types. Raises an exception.""" |
| |
| raise _DecodeError('Tag had invalid wire type.') |
| |
| def _FieldSkipper(): |
| """Constructs the SkipField function.""" |
| |
| WIRETYPE_TO_SKIPPER = [ |
| _SkipVarint, |
| _SkipFixed64, |
| _SkipLengthDelimited, |
| _SkipGroup, |
| _EndGroup, |
| _SkipFixed32, |
| _RaiseInvalidWireType, |
| _RaiseInvalidWireType, |
| ] |
| |
| wiretype_mask = wire_format.TAG_TYPE_MASK |
| |
| def SkipField(buffer, pos, end, tag_bytes): |
| """Skips a field with the specified tag. |
| |
| |pos| should point to the byte immediately after the tag. |
| |
| Returns: |
| The new position (after the tag value), or -1 if the tag is an end-group |
| tag (in which case the calling loop should break). |
| """ |
| |
| |
| wire_type = ord(tag_bytes[0:1]) & wiretype_mask |
| return WIRETYPE_TO_SKIPPER[wire_type](buffer, pos, end) |
| |
| return SkipField |
| |
| SkipField = _FieldSkipper() |
