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Diffstat (limited to 'generator/google/protobuf/internal/decoder.py')
| -rw-r--r-- | generator/google/protobuf/internal/decoder.py | 854 |
1 files changed, 0 insertions, 854 deletions
diff --git a/generator/google/protobuf/internal/decoder.py b/generator/google/protobuf/internal/decoder.py deleted file mode 100644 index 31869e4..0000000 --- a/generator/google/protobuf/internal/decoder.py +++ /dev/null @@ -1,854 +0,0 @@ -# Protocol Buffers - Google's data interchange format -# Copyright 2008 Google Inc. All rights reserved. -# https://developers.google.com/protocol-buffers/ -# -# Redistribution and use in source and binary forms, with or without -# modification, are permitted provided that the following conditions are -# met: -# -# * Redistributions of source code must retain the above copyright -# notice, this list of conditions and the following disclaimer. -# * Redistributions in binary form must reproduce the above -# copyright notice, this list of conditions and the following disclaimer -# in the documentation and/or other materials provided with the -# distribution. -# * Neither the name of Google Inc. nor the names of its -# contributors may be used to endorse or promote products derived from -# this software without specific prior written permission. -# -# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS -# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT -# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR -# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT -# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, -# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT -# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, -# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY -# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT -# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE -# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. - -"""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. -""" - -__author__ = 'kenton@google.com (Kenton Varda)' - -import struct - -import six - -if six.PY3: - long = int - -from google.protobuf.internal import encoder -from google.protobuf.internal import wire_format -from google.protobuf import message - - -# This will overflow and thus become IEEE-754 "infinity". We would use -# "float('inf')" but it doesn't work on Windows pre-Python-2.6. -_POS_INF = 1e10000 -_NEG_INF = -_POS_INF -_NAN = _POS_INF * 0 - - -# This is not for optimization, but rather to avoid conflicts with local -# variables named "message". -_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. - """ - - def DecodeVarint(buffer, pos): - result = 0 - shift = 0 - while 1: - b = six.indexbytes(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.""" - - def DecodeVarint(buffer, pos): - result = 0 - shift = 0 - while 1: - b = six.indexbytes(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 - -# We force 32-bit values to int and 64-bit values to long to make -# alternate implementations where the distinction is more significant -# (e.g. the C++ implementation) simpler. - -_DecodeVarint = _VarintDecoder((1 << 64) - 1, long) -_DecodeSignedVarint = _SignedVarintDecoder((1 << 64) - 1, long) - -# Use these versions for values which must be limited to 32 bits. -_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. - """ - - start = pos - while six.indexbytes(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] # Discard corrupt value. - 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) - # 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. - 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] # Discard corrupt value. - 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. - """ - - # Reusing _SimpleDecoder is slightly slower than copying a bunch of code, but - # not enough to make a significant difference. - - 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 - - # Reusing _SimpleDecoder is slightly slower than copying a bunch of code, but - # not enough to make a significant difference. - - # Note that we expect someone up-stack to catch struct.error and convert - # it to _DecodeError -- this way we don't have to set up exception- - # handling blocks every time we parse one value. - - 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 - - def InnerDecode(buffer, pos): - # We expect a 32-bit value in little-endian byte order. Bit 1 is the sign - # bit, bits 2-9 represent the exponent, and bits 10-32 are the significand. - new_pos = pos + 4 - float_bytes = buffer[pos:new_pos] - - # If this value has all its exponent bits set, then it's non-finite. - # In Python 2.4, struct.unpack will convert it to a finite 64-bit value. - # To avoid that, we parse it specially. - if (float_bytes[3:4] in b'\x7F\xFF' and float_bytes[2:3] >= b'\x80'): - # If at least one significand bit is set... - if float_bytes[0:3] != b'\x00\x00\x80': - return (_NAN, new_pos) - # If sign bit is set... - if float_bytes[3:4] == b'\xFF': - return (_NEG_INF, new_pos) - return (_POS_INF, new_pos) - - # Note that we expect someone up-stack to catch struct.error and convert - # it to _DecodeError -- this way we don't have to set up exception- - # handling blocks every time we parse one value. - 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 - - def InnerDecode(buffer, pos): - # We expect a 64-bit value in little-endian byte order. Bit 1 is the sign - # bit, bits 2-12 represent the exponent, and bits 13-64 are the significand. - new_pos = pos + 8 - double_bytes = buffer[pos:new_pos] - - # If this value has all its exponent bits set and at least one significand - # bit set, it's not a number. In Python 2.4, struct.unpack will treat it - # as inf or -inf. To avoid that, we treat it specially. - 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) - - # Note that we expect someone up-stack to catch struct.error and convert - # it to _DecodeError -- this way we don't have to set up exception- - # handling blocks every time we parse one value. - 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] # Discard corrupt value. - 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])) - # 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. - 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) - -# Note that Python conveniently guarantees that when using the '<' prefix on -# formats, they will also have the same size across all platforms (as opposed -# to without the prefix, where their sizes depend on the C compiler's basic -# type sizes). -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 = six.text_type - - def _ConvertToUnicode(byte_str): - try: - return local_unicode(byte_str, 'utf-8') - except UnicodeDecodeError as e: - # add more information to the error message and re-raise it. - 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])) - # 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 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]) - # 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 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)) - # Read sub-message. - pos = value.add()._InternalParse(buffer, pos, end) - # Read end tag. - new_pos = pos+end_tag_len - if buffer[pos:new_pos] != end_tag_bytes or new_pos > end: - raise _DecodeError('Missing group end tag.') - # 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 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)) - # Read sub-message. - pos = value._InternalParse(buffer, pos, end) - # Read end tag. - 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: - # Read length. - (size, pos) = local_DecodeVarint(buffer, pos) - new_pos = pos + size - if new_pos > end: - raise _DecodeError('Truncated message.') - # Read sub-message. - if value.add()._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.') - # 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 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)) - # Read length. - (size, pos) = local_DecodeVarint(buffer, pos) - new_pos = pos + size - if new_pos > end: - raise _DecodeError('Truncated message.') - # Read sub-message. - if value._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.') - 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 - - # Technically, type_id and message can appear in any order, so we need - # a little loop here. - 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: - # The only reason _InternalParse would return early is if it encountered - # an end-group tag. - 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 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. - -def _SkipVarint(buffer, pos, end): - """Skip a varint value. Returns the new position.""" - # Previously ord(buffer[pos]) raised IndexError when pos is out of range. - # With this code, ord(b'') raises TypeError. Both are handled in - # python_message.py to generate a 'Truncated message' error. - 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). - """ - - # The wire type is always in the first byte since varints are little-endian. - wire_type = ord(tag_bytes[0:1]) & wiretype_mask - return WIRETYPE_TO_SKIPPER[wire_type](buffer, pos, end) - - return SkipField - -SkipField = _FieldSkipper() |