/usr/share/pyshared/google/protobuf/internal/decoder.py is in python-protobuf 2.4.1-1ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 | # Protocol Buffers - Google's data interchange format
# Copyright 2008 Google Inc. All rights reserved.
# http://code.google.com/p/protobuf/
#
# 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
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):
"""Return an encoder for a basic varint value (does not include tag).
Decoded values will be bitwise-anded with the given mask before being
returned, e.g. to limit them to 32 bits. The returned decoder does not
take the usual "end" parameter -- the caller is expected to do bounds checking
after the fact (often the caller can defer such checking until later). The
decoder returns a (value, new_pos) pair.
"""
local_ord = ord
def DecodeVarint(buffer, pos):
result = 0
shift = 0
while 1:
b = local_ord(buffer[pos])
result |= ((b & 0x7f) << shift)
pos += 1
if not (b & 0x80):
result &= mask
return (result, pos)
shift += 7
if shift >= 64:
raise _DecodeError('Too many bytes when decoding varint.')
return DecodeVarint
def _SignedVarintDecoder(mask):
"""Like _VarintDecoder() but decodes signed values."""
local_ord = ord
def DecodeVarint(buffer, pos):
result = 0
shift = 0
while 1:
b = local_ord(buffer[pos])
result |= ((b & 0x7f) << shift)
pos += 1
if not (b & 0x80):
if result > 0x7fffffffffffffff:
result -= (1 << 64)
result |= ~mask
else:
result &= mask
return (result, pos)
shift += 7
if shift >= 64:
raise _DecodeError('Too many bytes when decoding varint.')
return DecodeVarint
_DecodeVarint = _VarintDecoder((1 << 64) - 1)
_DecodeSignedVarint = _SignedVarintDecoder((1 << 64) - 1)
# Use these versions for values which must be limited to 32 bits.
_DecodeVarint32 = _VarintDecoder((1 << 32) - 1)
_DecodeSignedVarint32 = _SignedVarintDecoder((1 << 32) - 1)
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 ord(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] in '\x7F\xFF')
and (float_bytes[2] >= '\x80')):
# If at least one significand bit is set...
if float_bytes[0:3] != '\x00\x00\x80':
return (_NAN, new_pos)
# If sign bit is set...
if float_bytes[3] == '\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] in '\x7F\xFF')
and (double_bytes[6] >= '\xF0')
and (double_bytes[0:7] != '\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)
# --------------------------------------------------------------------
Int32Decoder = EnumDecoder = _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 = unicode
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(local_unicode(buffer[pos:new_pos], 'utf-8'))
# 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] = local_unicode(buffer[pos:new_pos], 'utf-8')
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:
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.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):
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.')
return pos
return DecodeItem
# --------------------------------------------------------------------
# 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."""
while ord(buffer[pos]) & 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
local_ord = ord
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 = local_ord(tag_bytes[0]) & wiretype_mask
return WIRETYPE_TO_SKIPPER[wire_type](buffer, pos, end)
return SkipField
SkipField = _FieldSkipper()
|