Initial Contribution
diff --git a/froofle/protobuf/internal/decoder.py b/froofle/protobuf/internal/decoder.py
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+# 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.
+
+"""Class for decoding protocol buffer primitives.
+
+Contains the logic for decoding every logical protocol field type
+from one of the 5 physical wire types.
+"""
+
+__author__ = 'robinson@google.com (Will Robinson)'
+
+import struct
+from froofle.protobuf import message
+from froofle.protobuf.internal import input_stream
+from froofle.protobuf.internal import wire_format
+
+
+
+# Note that much of this code is ported from //net/proto/ProtocolBuffer, and
+# that the interface is strongly inspired by WireFormat from the C++ proto2
+# implementation.
+
+
+class Decoder(object):
+
+ """Decodes logical protocol buffer fields from the wire."""
+
+ def __init__(self, s):
+ """Initializes the decoder to read from s.
+
+ Args:
+ s: An immutable sequence of bytes, which must be accessible
+ via the Python buffer() primitive (i.e., buffer(s)).
+ """
+ self._stream = input_stream.InputStream(s)
+
+ def EndOfStream(self):
+ """Returns true iff we've reached the end of the bytes we're reading."""
+ return self._stream.EndOfStream()
+
+ def Position(self):
+ """Returns the 0-indexed position in |s|."""
+ return self._stream.Position()
+
+ def ReadFieldNumberAndWireType(self):
+ """Reads a tag from the wire. Returns a (field_number, wire_type) pair."""
+ tag_and_type = self.ReadUInt32()
+ return wire_format.UnpackTag(tag_and_type)
+
+ def SkipBytes(self, bytes):
+ """Skips the specified number of bytes on the wire."""
+ self._stream.SkipBytes(bytes)
+
+ # Note that the Read*() methods below are not exactly symmetrical with the
+ # corresponding Encoder.Append*() methods. Those Encoder methods first
+ # encode a tag, but the Read*() methods below assume that the tag has already
+ # been read, and that the client wishes to read a field of the specified type
+ # starting at the current position.
+
+ def ReadInt32(self):
+ """Reads and returns a signed, varint-encoded, 32-bit integer."""
+ return self._stream.ReadVarint32()
+
+ def ReadInt64(self):
+ """Reads and returns a signed, varint-encoded, 64-bit integer."""
+ return self._stream.ReadVarint64()
+
+ def ReadUInt32(self):
+ """Reads and returns an signed, varint-encoded, 32-bit integer."""
+ return self._stream.ReadVarUInt32()
+
+ def ReadUInt64(self):
+ """Reads and returns an signed, varint-encoded,64-bit integer."""
+ return self._stream.ReadVarUInt64()
+
+ def ReadSInt32(self):
+ """Reads and returns a signed, zigzag-encoded, varint-encoded,
+ 32-bit integer."""
+ return wire_format.ZigZagDecode(self._stream.ReadVarUInt32())
+
+ def ReadSInt64(self):
+ """Reads and returns a signed, zigzag-encoded, varint-encoded,
+ 64-bit integer."""
+ return wire_format.ZigZagDecode(self._stream.ReadVarUInt64())
+
+ def ReadFixed32(self):
+ """Reads and returns an unsigned, fixed-width, 32-bit integer."""
+ return self._stream.ReadLittleEndian32()
+
+ def ReadFixed64(self):
+ """Reads and returns an unsigned, fixed-width, 64-bit integer."""
+ return self._stream.ReadLittleEndian64()
+
+ def ReadSFixed32(self):
+ """Reads and returns a signed, fixed-width, 32-bit integer."""
+ value = self._stream.ReadLittleEndian32()
+ if value >= (1 << 31):
+ value -= (1 << 32)
+ return value
+
+ def ReadSFixed64(self):
+ """Reads and returns a signed, fixed-width, 64-bit integer."""
+ value = self._stream.ReadLittleEndian64()
+ if value >= (1 << 63):
+ value -= (1 << 64)
+ return value
+
+ def ReadFloat(self):
+ """Reads and returns a 4-byte floating-point number."""
+ serialized = self._stream.ReadBytes(4)
+ return struct.unpack('f', serialized)[0]
+
+ def ReadDouble(self):
+ """Reads and returns an 8-byte floating-point number."""
+ serialized = self._stream.ReadBytes(8)
+ return struct.unpack('d', serialized)[0]
+
+ def ReadBool(self):
+ """Reads and returns a bool."""
+ i = self._stream.ReadVarUInt32()
+ return bool(i)
+
+ def ReadEnum(self):
+ """Reads and returns an enum value."""
+ return self._stream.ReadVarUInt32()
+
+ def ReadString(self):
+ """Reads and returns a length-delimited string."""
+ bytes = self.ReadBytes()
+ return unicode(bytes, 'utf-8')
+
+ def ReadBytes(self):
+ """Reads and returns a length-delimited byte sequence."""
+ length = self._stream.ReadVarUInt32()
+ return self._stream.ReadBytes(length)
+
+ def ReadMessageInto(self, msg):
+ """Calls msg.MergeFromString() to merge
+ length-delimited serialized message data into |msg|.
+
+ REQUIRES: The decoder must be positioned at the serialized "length"
+ prefix to a length-delmiited serialized message.
+
+ POSTCONDITION: The decoder is positioned just after the
+ serialized message, and we have merged those serialized
+ contents into |msg|.
+ """
+ length = self._stream.ReadVarUInt32()
+ sub_buffer = self._stream.GetSubBuffer(length)
+ num_bytes_used = msg.MergeFromString(sub_buffer)
+ if num_bytes_used != length:
+ raise message.DecodeError(
+ 'Submessage told to deserialize from %d-byte encoding, '
+ 'but used only %d bytes' % (length, num_bytes_used))
+ self._stream.SkipBytes(num_bytes_used)
+
+ def ReadGroupInto(self, expected_field_number, group):
+ """Calls group.MergeFromString() to merge
+ END_GROUP-delimited serialized message data into |group|.
+ We'll raise an exception if we don't find an END_GROUP
+ tag immediately after the serialized message contents.
+
+ REQUIRES: The decoder is positioned just after the START_GROUP
+ tag for this group.
+
+ POSTCONDITION: The decoder is positioned just after the
+ END_GROUP tag for this group, and we have merged
+ the contents of the group into |group|.
+ """
+ sub_buffer = self._stream.GetSubBuffer() # No a priori length limit.
+ num_bytes_used = group.MergeFromString(sub_buffer)
+ if num_bytes_used < 0:
+ raise message.DecodeError('Group message reported negative bytes read.')
+ self._stream.SkipBytes(num_bytes_used)
+ field_number, field_type = self.ReadFieldNumberAndWireType()
+ if field_type != wire_format.WIRETYPE_END_GROUP:
+ raise message.DecodeError('Group message did not end with an END_GROUP.')
+ if field_number != expected_field_number:
+ raise message.DecodeError('END_GROUP tag had field '
+ 'number %d, was expecting field number %d' % (
+ field_number, expected_field_number))
+ # We're now positioned just after the END_GROUP tag. Perfect.