854 lines
31 KiB
Python
854 lines
31 KiB
Python
# Protocol Buffers - Google's data interchange format
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# Copyright 2008 Google Inc. All rights reserved.
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# https://developers.google.com/protocol-buffers/
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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#
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# * Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above
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# copyright notice, this list of conditions and the following disclaimer
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# in the documentation and/or other materials provided with the
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# distribution.
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# * Neither the name of Google Inc. nor the names of its
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# contributors may be used to endorse or promote products derived from
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# this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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"""Code for decoding protocol buffer primitives.
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This code is very similar to encoder.py -- read the docs for that module first.
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A "decoder" is a function with the signature:
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Decode(buffer, pos, end, message, field_dict)
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The arguments are:
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buffer: The string containing the encoded message.
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pos: The current position in the string.
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end: The position in the string where the current message ends. May be
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less than len(buffer) if we're reading a sub-message.
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message: The message object into which we're parsing.
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field_dict: message._fields (avoids a hashtable lookup).
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The decoder reads the field and stores it into field_dict, returning the new
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buffer position. A decoder for a repeated field may proactively decode all of
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the elements of that field, if they appear consecutively.
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Note that decoders may throw any of the following:
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IndexError: Indicates a truncated message.
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struct.error: Unpacking of a fixed-width field failed.
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message.DecodeError: Other errors.
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Decoders are expected to raise an exception if they are called with pos > end.
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This allows callers to be lax about bounds checking: it's fineto read past
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"end" as long as you are sure that someone else will notice and throw an
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exception later on.
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Something up the call stack is expected to catch IndexError and struct.error
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and convert them to message.DecodeError.
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Decoders are constructed using decoder constructors with the signature:
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MakeDecoder(field_number, is_repeated, is_packed, key, new_default)
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The arguments are:
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field_number: The field number of the field we want to decode.
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is_repeated: Is the field a repeated field? (bool)
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is_packed: Is the field a packed field? (bool)
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key: The key to use when looking up the field within field_dict.
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(This is actually the FieldDescriptor but nothing in this
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file should depend on that.)
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new_default: A function which takes a message object as a parameter and
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returns a new instance of the default value for this field.
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(This is called for repeated fields and sub-messages, when an
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instance does not already exist.)
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As with encoders, we define a decoder constructor for every type of field.
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Then, for every field of every message class we construct an actual decoder.
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That decoder goes into a dict indexed by tag, so when we decode a message
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we repeatedly read a tag, look up the corresponding decoder, and invoke it.
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"""
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__author__ = 'kenton@google.com (Kenton Varda)'
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import struct
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import six
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if six.PY3:
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long = int
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from google.protobuf.internal import encoder
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from google.protobuf.internal import wire_format
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from google.protobuf import message
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# This will overflow and thus become IEEE-754 "infinity". We would use
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# "float('inf')" but it doesn't work on Windows pre-Python-2.6.
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_POS_INF = 1e10000
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_NEG_INF = -_POS_INF
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_NAN = _POS_INF * 0
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# This is not for optimization, but rather to avoid conflicts with local
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# variables named "message".
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_DecodeError = message.DecodeError
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def _VarintDecoder(mask, result_type):
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"""Return an encoder for a basic varint value (does not include tag).
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Decoded values will be bitwise-anded with the given mask before being
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returned, e.g. to limit them to 32 bits. The returned decoder does not
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take the usual "end" parameter -- the caller is expected to do bounds checking
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after the fact (often the caller can defer such checking until later). The
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decoder returns a (value, new_pos) pair.
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"""
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def DecodeVarint(buffer, pos):
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result = 0
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shift = 0
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while 1:
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b = six.indexbytes(buffer, pos)
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result |= ((b & 0x7f) << shift)
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pos += 1
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if not (b & 0x80):
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result &= mask
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result = result_type(result)
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return (result, pos)
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shift += 7
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if shift >= 64:
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raise _DecodeError('Too many bytes when decoding varint.')
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return DecodeVarint
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def _SignedVarintDecoder(bits, result_type):
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"""Like _VarintDecoder() but decodes signed values."""
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signbit = 1 << (bits - 1)
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mask = (1 << bits) - 1
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def DecodeVarint(buffer, pos):
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result = 0
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shift = 0
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while 1:
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b = six.indexbytes(buffer, pos)
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result |= ((b & 0x7f) << shift)
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pos += 1
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if not (b & 0x80):
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result &= mask
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result = (result ^ signbit) - signbit
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result = result_type(result)
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return (result, pos)
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shift += 7
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if shift >= 64:
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raise _DecodeError('Too many bytes when decoding varint.')
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return DecodeVarint
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# We force 32-bit values to int and 64-bit values to long to make
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# alternate implementations where the distinction is more significant
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# (e.g. the C++ implementation) simpler.
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_DecodeVarint = _VarintDecoder((1 << 64) - 1, int)
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_DecodeSignedVarint = _SignedVarintDecoder(64, int)
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# Use these versions for values which must be limited to 32 bits.
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_DecodeVarint32 = _VarintDecoder((1 << 32) - 1, int)
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_DecodeSignedVarint32 = _SignedVarintDecoder(32, int)
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def ReadTag(buffer, pos):
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"""Read a tag from the buffer, and return a (tag_bytes, new_pos) tuple.
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We return the raw bytes of the tag rather than decoding them. The raw
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bytes can then be used to look up the proper decoder. This effectively allows
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us to trade some work that would be done in pure-python (decoding a varint)
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for work that is done in C (searching for a byte string in a hash table).
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In a low-level language it would be much cheaper to decode the varint and
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use that, but not in Python.
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"""
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start = pos
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while six.indexbytes(buffer, pos) & 0x80:
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pos += 1
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pos += 1
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return (six.binary_type(buffer[start:pos]), pos)
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# --------------------------------------------------------------------
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def _SimpleDecoder(wire_type, decode_value):
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"""Return a constructor for a decoder for fields of a particular type.
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Args:
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wire_type: The field's wire type.
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decode_value: A function which decodes an individual value, e.g.
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_DecodeVarint()
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"""
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def SpecificDecoder(field_number, is_repeated, is_packed, key, new_default):
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if is_packed:
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local_DecodeVarint = _DecodeVarint
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def DecodePackedField(buffer, pos, end, message, field_dict):
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value = field_dict.get(key)
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if value is None:
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value = field_dict.setdefault(key, new_default(message))
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(endpoint, pos) = local_DecodeVarint(buffer, pos)
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endpoint += pos
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if endpoint > end:
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raise _DecodeError('Truncated message.')
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while pos < endpoint:
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(element, pos) = decode_value(buffer, pos)
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value.append(element)
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if pos > endpoint:
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del value[-1] # Discard corrupt value.
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raise _DecodeError('Packed element was truncated.')
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return pos
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return DecodePackedField
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elif is_repeated:
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tag_bytes = encoder.TagBytes(field_number, wire_type)
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tag_len = len(tag_bytes)
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def DecodeRepeatedField(buffer, pos, end, message, field_dict):
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value = field_dict.get(key)
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if value is None:
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value = field_dict.setdefault(key, new_default(message))
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while 1:
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(element, new_pos) = decode_value(buffer, pos)
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value.append(element)
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# Predict that the next tag is another copy of the same repeated
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# field.
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pos = new_pos + tag_len
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if buffer[new_pos:pos] != tag_bytes or new_pos >= end:
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# Prediction failed. Return.
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if new_pos > end:
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raise _DecodeError('Truncated message.')
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return new_pos
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return DecodeRepeatedField
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else:
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def DecodeField(buffer, pos, end, message, field_dict):
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(field_dict[key], pos) = decode_value(buffer, pos)
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if pos > end:
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del field_dict[key] # Discard corrupt value.
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raise _DecodeError('Truncated message.')
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return pos
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return DecodeField
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return SpecificDecoder
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def _ModifiedDecoder(wire_type, decode_value, modify_value):
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"""Like SimpleDecoder but additionally invokes modify_value on every value
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before storing it. Usually modify_value is ZigZagDecode.
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"""
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# Reusing _SimpleDecoder is slightly slower than copying a bunch of code, but
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# not enough to make a significant difference.
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def InnerDecode(buffer, pos):
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(result, new_pos) = decode_value(buffer, pos)
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return (modify_value(result), new_pos)
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return _SimpleDecoder(wire_type, InnerDecode)
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def _StructPackDecoder(wire_type, format):
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"""Return a constructor for a decoder for a fixed-width field.
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Args:
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wire_type: The field's wire type.
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format: The format string to pass to struct.unpack().
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"""
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value_size = struct.calcsize(format)
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local_unpack = struct.unpack
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# Reusing _SimpleDecoder is slightly slower than copying a bunch of code, but
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# not enough to make a significant difference.
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# Note that we expect someone up-stack to catch struct.error and convert
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# it to _DecodeError -- this way we don't have to set up exception-
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# handling blocks every time we parse one value.
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def InnerDecode(buffer, pos):
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new_pos = pos + value_size
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result = local_unpack(format, buffer[pos:new_pos])[0]
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return (result, new_pos)
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return _SimpleDecoder(wire_type, InnerDecode)
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def _FloatDecoder():
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"""Returns a decoder for a float field.
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This code works around a bug in struct.unpack for non-finite 32-bit
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floating-point values.
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"""
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local_unpack = struct.unpack
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def InnerDecode(buffer, pos):
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# We expect a 32-bit value in little-endian byte order. Bit 1 is the sign
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# bit, bits 2-9 represent the exponent, and bits 10-32 are the significand.
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new_pos = pos + 4
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float_bytes = buffer[pos:new_pos]
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# If this value has all its exponent bits set, then it's non-finite.
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# In Python 2.4, struct.unpack will convert it to a finite 64-bit value.
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# To avoid that, we parse it specially.
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if (float_bytes[3:4] in b'\x7F\xFF' and float_bytes[2:3] >= b'\x80'):
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# If at least one significand bit is set...
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if float_bytes[0:3] != b'\x00\x00\x80':
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return (_NAN, new_pos)
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# If sign bit is set...
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if float_bytes[3:4] == b'\xFF':
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return (_NEG_INF, new_pos)
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return (_POS_INF, new_pos)
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# Note that we expect someone up-stack to catch struct.error and convert
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# it to _DecodeError -- this way we don't have to set up exception-
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# handling blocks every time we parse one value.
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result = local_unpack('<f', float_bytes)[0]
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return (result, new_pos)
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return _SimpleDecoder(wire_format.WIRETYPE_FIXED32, InnerDecode)
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def _DoubleDecoder():
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"""Returns a decoder for a double field.
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This code works around a bug in struct.unpack for not-a-number.
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"""
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local_unpack = struct.unpack
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def InnerDecode(buffer, pos):
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# We expect a 64-bit value in little-endian byte order. Bit 1 is the sign
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# bit, bits 2-12 represent the exponent, and bits 13-64 are the significand.
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new_pos = pos + 8
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double_bytes = buffer[pos:new_pos]
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# If this value has all its exponent bits set and at least one significand
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# bit set, it's not a number. In Python 2.4, struct.unpack will treat it
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# as inf or -inf. To avoid that, we treat it specially.
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if ((double_bytes[7:8] in b'\x7F\xFF')
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and (double_bytes[6:7] >= b'\xF0')
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and (double_bytes[0:7] != b'\x00\x00\x00\x00\x00\x00\xF0')):
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return (_NAN, new_pos)
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# Note that we expect someone up-stack to catch struct.error and convert
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# it to _DecodeError -- this way we don't have to set up exception-
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# handling blocks every time we parse one value.
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result = local_unpack('<d', double_bytes)[0]
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return (result, new_pos)
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return _SimpleDecoder(wire_format.WIRETYPE_FIXED64, InnerDecode)
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def EnumDecoder(field_number, is_repeated, is_packed, key, new_default):
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enum_type = key.enum_type
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if is_packed:
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local_DecodeVarint = _DecodeVarint
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def DecodePackedField(buffer, pos, end, message, field_dict):
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value = field_dict.get(key)
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if value is None:
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value = field_dict.setdefault(key, new_default(message))
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(endpoint, pos) = local_DecodeVarint(buffer, pos)
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endpoint += pos
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if endpoint > end:
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raise _DecodeError('Truncated message.')
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while pos < endpoint:
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value_start_pos = pos
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(element, pos) = _DecodeSignedVarint32(buffer, pos)
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if element in enum_type.values_by_number:
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value.append(element)
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else:
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if not message._unknown_fields:
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message._unknown_fields = []
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tag_bytes = encoder.TagBytes(field_number,
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wire_format.WIRETYPE_VARINT)
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message._unknown_fields.append(
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(tag_bytes, buffer[value_start_pos:pos]))
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if pos > endpoint:
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if element in enum_type.values_by_number:
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del value[-1] # Discard corrupt value.
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else:
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del message._unknown_fields[-1]
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raise _DecodeError('Packed element was truncated.')
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return pos
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return DecodePackedField
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elif is_repeated:
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tag_bytes = encoder.TagBytes(field_number, wire_format.WIRETYPE_VARINT)
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tag_len = len(tag_bytes)
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def DecodeRepeatedField(buffer, pos, end, message, field_dict):
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value = field_dict.get(key)
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if value is None:
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value = field_dict.setdefault(key, new_default(message))
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while 1:
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(element, new_pos) = _DecodeSignedVarint32(buffer, pos)
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if element in enum_type.values_by_number:
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value.append(element)
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else:
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if not message._unknown_fields:
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message._unknown_fields = []
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message._unknown_fields.append(
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(tag_bytes, buffer[pos:new_pos]))
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# Predict that the next tag is another copy of the same repeated
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# field.
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pos = new_pos + tag_len
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if buffer[new_pos:pos] != tag_bytes or new_pos >= end:
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# Prediction failed. Return.
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if new_pos > end:
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raise _DecodeError('Truncated message.')
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return new_pos
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return DecodeRepeatedField
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else:
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def DecodeField(buffer, pos, end, message, field_dict):
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value_start_pos = pos
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(enum_value, pos) = _DecodeSignedVarint32(buffer, pos)
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if pos > end:
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raise _DecodeError('Truncated message.')
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if enum_value in enum_type.values_by_number:
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field_dict[key] = enum_value
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else:
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if not message._unknown_fields:
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message._unknown_fields = []
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tag_bytes = encoder.TagBytes(field_number,
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wire_format.WIRETYPE_VARINT)
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message._unknown_fields.append(
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(tag_bytes, buffer[value_start_pos:pos]))
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return pos
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return DecodeField
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# --------------------------------------------------------------------
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Int32Decoder = _SimpleDecoder(
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wire_format.WIRETYPE_VARINT, _DecodeSignedVarint32)
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Int64Decoder = _SimpleDecoder(
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wire_format.WIRETYPE_VARINT, _DecodeSignedVarint)
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UInt32Decoder = _SimpleDecoder(wire_format.WIRETYPE_VARINT, _DecodeVarint32)
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UInt64Decoder = _SimpleDecoder(wire_format.WIRETYPE_VARINT, _DecodeVarint)
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SInt32Decoder = _ModifiedDecoder(
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wire_format.WIRETYPE_VARINT, _DecodeVarint32, wire_format.ZigZagDecode)
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SInt64Decoder = _ModifiedDecoder(
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wire_format.WIRETYPE_VARINT, _DecodeVarint, wire_format.ZigZagDecode)
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# Note that Python conveniently guarantees that when using the '<' prefix on
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# formats, they will also have the same size across all platforms (as opposed
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# to without the prefix, where their sizes depend on the C compiler's basic
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# type sizes).
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Fixed32Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED32, '<I')
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Fixed64Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED64, '<Q')
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SFixed32Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED32, '<i')
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SFixed64Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED64, '<q')
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FloatDecoder = _FloatDecoder()
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DoubleDecoder = _DoubleDecoder()
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BoolDecoder = _ModifiedDecoder(
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wire_format.WIRETYPE_VARINT, _DecodeVarint, bool)
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def StringDecoder(field_number, is_repeated, is_packed, key, new_default):
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"""Returns a decoder for a string field."""
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local_DecodeVarint = _DecodeVarint
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local_unicode = six.text_type
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def _ConvertToUnicode(byte_str):
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try:
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return local_unicode(byte_str, 'utf-8')
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except UnicodeDecodeError as e:
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# add more information to the error message and re-raise it.
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e.reason = '%s in field: %s' % (e, key.full_name)
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raise
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assert not is_packed
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if is_repeated:
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tag_bytes = encoder.TagBytes(field_number,
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wire_format.WIRETYPE_LENGTH_DELIMITED)
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tag_len = len(tag_bytes)
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def DecodeRepeatedField(buffer, pos, end, message, field_dict):
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value = field_dict.get(key)
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|
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(descriptor):
|
|
"""Returns a decoder for a MessageSet item.
|
|
|
|
The parameter is the message Descriptor.
|
|
|
|
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 = message.Extensions._FindExtensionByNumber(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()
|