268 lines
8.2 KiB
Python
268 lines
8.2 KiB
Python
# 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.
|
|
|
|
"""Constants and static functions to support protocol buffer wire format."""
|
|
|
|
__author__ = 'robinson@google.com (Will Robinson)'
|
|
|
|
import struct
|
|
from google.protobuf import descriptor
|
|
from google.protobuf import message
|
|
|
|
|
|
TAG_TYPE_BITS = 3 # Number of bits used to hold type info in a proto tag.
|
|
TAG_TYPE_MASK = (1 << TAG_TYPE_BITS) - 1 # 0x7
|
|
|
|
# These numbers identify the wire type of a protocol buffer value.
|
|
# We use the least-significant TAG_TYPE_BITS bits of the varint-encoded
|
|
# tag-and-type to store one of these WIRETYPE_* constants.
|
|
# These values must match WireType enum in google/protobuf/wire_format.h.
|
|
WIRETYPE_VARINT = 0
|
|
WIRETYPE_FIXED64 = 1
|
|
WIRETYPE_LENGTH_DELIMITED = 2
|
|
WIRETYPE_START_GROUP = 3
|
|
WIRETYPE_END_GROUP = 4
|
|
WIRETYPE_FIXED32 = 5
|
|
_WIRETYPE_MAX = 5
|
|
|
|
|
|
# Bounds for various integer types.
|
|
INT32_MAX = int((1 << 31) - 1)
|
|
INT32_MIN = int(-(1 << 31))
|
|
UINT32_MAX = (1 << 32) - 1
|
|
|
|
INT64_MAX = (1 << 63) - 1
|
|
INT64_MIN = -(1 << 63)
|
|
UINT64_MAX = (1 << 64) - 1
|
|
|
|
# "struct" format strings that will encode/decode the specified formats.
|
|
FORMAT_UINT32_LITTLE_ENDIAN = '<I'
|
|
FORMAT_UINT64_LITTLE_ENDIAN = '<Q'
|
|
FORMAT_FLOAT_LITTLE_ENDIAN = '<f'
|
|
FORMAT_DOUBLE_LITTLE_ENDIAN = '<d'
|
|
|
|
|
|
# We'll have to provide alternate implementations of AppendLittleEndian*() on
|
|
# any architectures where these checks fail.
|
|
if struct.calcsize(FORMAT_UINT32_LITTLE_ENDIAN) != 4:
|
|
raise AssertionError('Format "I" is not a 32-bit number.')
|
|
if struct.calcsize(FORMAT_UINT64_LITTLE_ENDIAN) != 8:
|
|
raise AssertionError('Format "Q" is not a 64-bit number.')
|
|
|
|
|
|
def PackTag(field_number, wire_type):
|
|
"""Returns an unsigned 32-bit integer that encodes the field number and
|
|
wire type information in standard protocol message wire format.
|
|
|
|
Args:
|
|
field_number: Expected to be an integer in the range [1, 1 << 29)
|
|
wire_type: One of the WIRETYPE_* constants.
|
|
"""
|
|
if not 0 <= wire_type <= _WIRETYPE_MAX:
|
|
raise message.EncodeError('Unknown wire type: %d' % wire_type)
|
|
return (field_number << TAG_TYPE_BITS) | wire_type
|
|
|
|
|
|
def UnpackTag(tag):
|
|
"""The inverse of PackTag(). Given an unsigned 32-bit number,
|
|
returns a (field_number, wire_type) tuple.
|
|
"""
|
|
return (tag >> TAG_TYPE_BITS), (tag & TAG_TYPE_MASK)
|
|
|
|
|
|
def ZigZagEncode(value):
|
|
"""ZigZag Transform: Encodes signed integers so that they can be
|
|
effectively used with varint encoding. See wire_format.h for
|
|
more details.
|
|
"""
|
|
if value >= 0:
|
|
return value << 1
|
|
return (value << 1) ^ (~0)
|
|
|
|
|
|
def ZigZagDecode(value):
|
|
"""Inverse of ZigZagEncode()."""
|
|
if not value & 0x1:
|
|
return value >> 1
|
|
return (value >> 1) ^ (~0)
|
|
|
|
|
|
|
|
# The *ByteSize() functions below return the number of bytes required to
|
|
# serialize "field number + type" information and then serialize the value.
|
|
|
|
|
|
def Int32ByteSize(field_number, int32):
|
|
return Int64ByteSize(field_number, int32)
|
|
|
|
|
|
def Int32ByteSizeNoTag(int32):
|
|
return _VarUInt64ByteSizeNoTag(0xffffffffffffffff & int32)
|
|
|
|
|
|
def Int64ByteSize(field_number, int64):
|
|
# Have to convert to uint before calling UInt64ByteSize().
|
|
return UInt64ByteSize(field_number, 0xffffffffffffffff & int64)
|
|
|
|
|
|
def UInt32ByteSize(field_number, uint32):
|
|
return UInt64ByteSize(field_number, uint32)
|
|
|
|
|
|
def UInt64ByteSize(field_number, uint64):
|
|
return TagByteSize(field_number) + _VarUInt64ByteSizeNoTag(uint64)
|
|
|
|
|
|
def SInt32ByteSize(field_number, int32):
|
|
return UInt32ByteSize(field_number, ZigZagEncode(int32))
|
|
|
|
|
|
def SInt64ByteSize(field_number, int64):
|
|
return UInt64ByteSize(field_number, ZigZagEncode(int64))
|
|
|
|
|
|
def Fixed32ByteSize(field_number, fixed32):
|
|
return TagByteSize(field_number) + 4
|
|
|
|
|
|
def Fixed64ByteSize(field_number, fixed64):
|
|
return TagByteSize(field_number) + 8
|
|
|
|
|
|
def SFixed32ByteSize(field_number, sfixed32):
|
|
return TagByteSize(field_number) + 4
|
|
|
|
|
|
def SFixed64ByteSize(field_number, sfixed64):
|
|
return TagByteSize(field_number) + 8
|
|
|
|
|
|
def FloatByteSize(field_number, flt):
|
|
return TagByteSize(field_number) + 4
|
|
|
|
|
|
def DoubleByteSize(field_number, double):
|
|
return TagByteSize(field_number) + 8
|
|
|
|
|
|
def BoolByteSize(field_number, b):
|
|
return TagByteSize(field_number) + 1
|
|
|
|
|
|
def EnumByteSize(field_number, enum):
|
|
return UInt32ByteSize(field_number, enum)
|
|
|
|
|
|
def StringByteSize(field_number, string):
|
|
return BytesByteSize(field_number, string.encode('utf-8'))
|
|
|
|
|
|
def BytesByteSize(field_number, b):
|
|
return (TagByteSize(field_number)
|
|
+ _VarUInt64ByteSizeNoTag(len(b))
|
|
+ len(b))
|
|
|
|
|
|
def GroupByteSize(field_number, message):
|
|
return (2 * TagByteSize(field_number) # START and END group.
|
|
+ message.ByteSize())
|
|
|
|
|
|
def MessageByteSize(field_number, message):
|
|
return (TagByteSize(field_number)
|
|
+ _VarUInt64ByteSizeNoTag(message.ByteSize())
|
|
+ message.ByteSize())
|
|
|
|
|
|
def MessageSetItemByteSize(field_number, msg):
|
|
# First compute the sizes of the tags.
|
|
# There are 2 tags for the beginning and ending of the repeated group, that
|
|
# is field number 1, one with field number 2 (type_id) and one with field
|
|
# number 3 (message).
|
|
total_size = (2 * TagByteSize(1) + TagByteSize(2) + TagByteSize(3))
|
|
|
|
# Add the number of bytes for type_id.
|
|
total_size += _VarUInt64ByteSizeNoTag(field_number)
|
|
|
|
message_size = msg.ByteSize()
|
|
|
|
# The number of bytes for encoding the length of the message.
|
|
total_size += _VarUInt64ByteSizeNoTag(message_size)
|
|
|
|
# The size of the message.
|
|
total_size += message_size
|
|
return total_size
|
|
|
|
|
|
def TagByteSize(field_number):
|
|
"""Returns the bytes required to serialize a tag with this field number."""
|
|
# Just pass in type 0, since the type won't affect the tag+type size.
|
|
return _VarUInt64ByteSizeNoTag(PackTag(field_number, 0))
|
|
|
|
|
|
# Private helper function for the *ByteSize() functions above.
|
|
|
|
def _VarUInt64ByteSizeNoTag(uint64):
|
|
"""Returns the number of bytes required to serialize a single varint
|
|
using boundary value comparisons. (unrolled loop optimization -WPierce)
|
|
uint64 must be unsigned.
|
|
"""
|
|
if uint64 <= 0x7f: return 1
|
|
if uint64 <= 0x3fff: return 2
|
|
if uint64 <= 0x1fffff: return 3
|
|
if uint64 <= 0xfffffff: return 4
|
|
if uint64 <= 0x7ffffffff: return 5
|
|
if uint64 <= 0x3ffffffffff: return 6
|
|
if uint64 <= 0x1ffffffffffff: return 7
|
|
if uint64 <= 0xffffffffffffff: return 8
|
|
if uint64 <= 0x7fffffffffffffff: return 9
|
|
if uint64 > UINT64_MAX:
|
|
raise message.EncodeError('Value out of range: %d' % uint64)
|
|
return 10
|
|
|
|
|
|
NON_PACKABLE_TYPES = (
|
|
descriptor.FieldDescriptor.TYPE_STRING,
|
|
descriptor.FieldDescriptor.TYPE_GROUP,
|
|
descriptor.FieldDescriptor.TYPE_MESSAGE,
|
|
descriptor.FieldDescriptor.TYPE_BYTES
|
|
)
|
|
|
|
|
|
def IsTypePackable(field_type):
|
|
"""Return true iff packable = true is valid for fields of this type.
|
|
|
|
Args:
|
|
field_type: a FieldDescriptor::Type value.
|
|
|
|
Returns:
|
|
True iff fields of this type are packable.
|
|
"""
|
|
return field_type not in NON_PACKABLE_TYPES
|