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207 lines
8.4 KiB
Python
207 lines
8.4 KiB
Python
# Protocol Buffers - Google's data interchange format
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# Copyright 2008 Google Inc. All rights reserved.
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# http://code.google.com/p/protobuf/
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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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"""Class for encoding protocol message primitives.
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Contains the logic for encoding every logical protocol field type
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into one of the 5 physical wire types.
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"""
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__author__ = 'robinson@google.com (Will Robinson)'
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import struct
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from froofle.protobuf import message
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from froofle.protobuf.internal import wire_format
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from froofle.protobuf.internal import output_stream
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# Note that much of this code is ported from //net/proto/ProtocolBuffer, and
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# that the interface is strongly inspired by WireFormat from the C++ proto2
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# implementation.
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class Encoder(object):
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"""Encodes logical protocol buffer fields to the wire format."""
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def __init__(self):
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self._stream = output_stream.OutputStream()
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def ToString(self):
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"""Returns all values encoded in this object as a string."""
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return self._stream.ToString()
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# All the Append*() methods below first append a tag+type pair to the buffer
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# before appending the specified value.
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def AppendInt32(self, field_number, value):
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"""Appends a 32-bit integer to our buffer, varint-encoded."""
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self._AppendTag(field_number, wire_format.WIRETYPE_VARINT)
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self._stream.AppendVarint32(value)
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def AppendInt64(self, field_number, value):
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"""Appends a 64-bit integer to our buffer, varint-encoded."""
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self._AppendTag(field_number, wire_format.WIRETYPE_VARINT)
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self._stream.AppendVarint64(value)
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def AppendUInt32(self, field_number, unsigned_value):
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"""Appends an unsigned 32-bit integer to our buffer, varint-encoded."""
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self._AppendTag(field_number, wire_format.WIRETYPE_VARINT)
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self._stream.AppendVarUInt32(unsigned_value)
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def AppendUInt64(self, field_number, unsigned_value):
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"""Appends an unsigned 64-bit integer to our buffer, varint-encoded."""
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self._AppendTag(field_number, wire_format.WIRETYPE_VARINT)
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self._stream.AppendVarUInt64(unsigned_value)
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def AppendSInt32(self, field_number, value):
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"""Appends a 32-bit integer to our buffer, zigzag-encoded and then
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varint-encoded.
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"""
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self._AppendTag(field_number, wire_format.WIRETYPE_VARINT)
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zigzag_value = wire_format.ZigZagEncode(value)
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self._stream.AppendVarUInt32(zigzag_value)
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def AppendSInt64(self, field_number, value):
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"""Appends a 64-bit integer to our buffer, zigzag-encoded and then
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varint-encoded.
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"""
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self._AppendTag(field_number, wire_format.WIRETYPE_VARINT)
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zigzag_value = wire_format.ZigZagEncode(value)
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self._stream.AppendVarUInt64(zigzag_value)
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def AppendFixed32(self, field_number, unsigned_value):
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"""Appends an unsigned 32-bit integer to our buffer, in little-endian
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byte-order.
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"""
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self._AppendTag(field_number, wire_format.WIRETYPE_FIXED32)
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self._stream.AppendLittleEndian32(unsigned_value)
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def AppendFixed64(self, field_number, unsigned_value):
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"""Appends an unsigned 64-bit integer to our buffer, in little-endian
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byte-order.
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"""
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self._AppendTag(field_number, wire_format.WIRETYPE_FIXED64)
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self._stream.AppendLittleEndian64(unsigned_value)
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def AppendSFixed32(self, field_number, value):
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"""Appends a signed 32-bit integer to our buffer, in little-endian
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byte-order.
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"""
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sign = (value & 0x80000000) and -1 or 0
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if value >> 32 != sign:
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raise message.EncodeError('SFixed32 out of range: %d' % value)
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self._AppendTag(field_number, wire_format.WIRETYPE_FIXED32)
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self._stream.AppendLittleEndian32(value & 0xffffffff)
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def AppendSFixed64(self, field_number, value):
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"""Appends a signed 64-bit integer to our buffer, in little-endian
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byte-order.
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"""
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sign = (value & 0x8000000000000000) and -1 or 0
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if value >> 64 != sign:
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raise message.EncodeError('SFixed64 out of range: %d' % value)
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self._AppendTag(field_number, wire_format.WIRETYPE_FIXED64)
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self._stream.AppendLittleEndian64(value & 0xffffffffffffffff)
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def AppendFloat(self, field_number, value):
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"""Appends a floating-point number to our buffer."""
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self._AppendTag(field_number, wire_format.WIRETYPE_FIXED32)
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self._stream.AppendRawBytes(struct.pack('f', value))
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def AppendDouble(self, field_number, value):
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"""Appends a double-precision floating-point number to our buffer."""
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self._AppendTag(field_number, wire_format.WIRETYPE_FIXED64)
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self._stream.AppendRawBytes(struct.pack('d', value))
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def AppendBool(self, field_number, value):
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"""Appends a boolean to our buffer."""
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self.AppendInt32(field_number, value)
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def AppendEnum(self, field_number, value):
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"""Appends an enum value to our buffer."""
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self.AppendInt32(field_number, value)
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def AppendString(self, field_number, value):
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"""Appends a length-prefixed unicode string, encoded as UTF-8 to our buffer,
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with the length varint-encoded.
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"""
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self.AppendBytes(field_number, value.encode('utf-8'))
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def AppendBytes(self, field_number, value):
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"""Appends a length-prefixed sequence of bytes to our buffer, with the
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length varint-encoded.
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"""
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self._AppendTag(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
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self._stream.AppendVarUInt32(len(value))
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self._stream.AppendRawBytes(value)
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# TODO(robinson): For AppendGroup() and AppendMessage(), we'd really like to
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# avoid the extra string copy here. We can do so if we widen the Message
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# interface to be able to serialize to a stream in addition to a string. The
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# challenge when thinking ahead to the Python/C API implementation of Message
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# is finding a stream-like Python thing to which we can write raw bytes
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# from C. I'm not sure such a thing exists(?). (array.array is pretty much
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# what we want, but it's not directly exposed in the Python/C API).
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def AppendGroup(self, field_number, group):
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"""Appends a group to our buffer.
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"""
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self._AppendTag(field_number, wire_format.WIRETYPE_START_GROUP)
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self._stream.AppendRawBytes(group.SerializeToString())
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self._AppendTag(field_number, wire_format.WIRETYPE_END_GROUP)
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def AppendMessage(self, field_number, msg):
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"""Appends a nested message to our buffer.
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"""
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self._AppendTag(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
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self._stream.AppendVarUInt32(msg.ByteSize())
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self._stream.AppendRawBytes(msg.SerializeToString())
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def AppendMessageSetItem(self, field_number, msg):
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"""Appends an item using the message set wire format.
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The message set message looks like this:
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message MessageSet {
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repeated group Item = 1 {
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required int32 type_id = 2;
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required string message = 3;
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}
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}
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"""
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self._AppendTag(1, wire_format.WIRETYPE_START_GROUP)
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self.AppendInt32(2, field_number)
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self.AppendMessage(3, msg)
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self._AppendTag(1, wire_format.WIRETYPE_END_GROUP)
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def _AppendTag(self, field_number, wire_type):
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"""Appends a tag containing field number and wire type information."""
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self._stream.AppendVarUInt32(wire_format.PackTag(field_number, wire_type))
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