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Diffstat (limited to 'python/google/protobuf/internal/wire_format.py')
-rwxr-xr-x | python/google/protobuf/internal/wire_format.py | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/python/google/protobuf/internal/wire_format.py b/python/google/protobuf/internal/wire_format.py new file mode 100755 index 00000000..883f5255 --- /dev/null +++ b/python/google/protobuf/internal/wire_format.py @@ -0,0 +1,268 @@ +# 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 |