public static void SkipLastField(ref ReadOnlySpan <byte> buffer, ref ParserInternalState state)
{
if (state.lastTag == 0)
{
throw new InvalidOperationException("SkipLastField cannot be called at the end of a stream");
}
switch (WireFormat.GetTagWireType(state.lastTag))
{
case WireFormat.WireType.StartGroup:
SkipGroup(ref buffer, ref state, state.lastTag);
break;
case WireFormat.WireType.EndGroup:
throw new InvalidProtocolBufferException(
"SkipLastField called on an end-group tag, indicating that the corresponding start-group was missing");
case WireFormat.WireType.Fixed32:
ParsingPrimitives.ParseRawLittleEndian32(ref buffer, ref state);
break;
case WireFormat.WireType.Fixed64:
ParsingPrimitives.ParseRawLittleEndian64(ref buffer, ref state);
break;
case WireFormat.WireType.LengthDelimited:
var length = ParsingPrimitives.ParseLength(ref buffer, ref state);
ParsingPrimitives.SkipRawBytes(ref buffer, ref state, length);
break;
case WireFormat.WireType.Varint:
ParsingPrimitives.ParseRawVarint32(ref buffer, ref state);
break;
}
}
internal static uint?ReadUInt32WrapperSlow(ref ReadOnlySpan <byte> buffer, ref ParserInternalState state)
{
int length = ParsingPrimitives.ParseLength(ref buffer, ref state);
if (length == 0)
{
return(0);
}
int finalBufferPos = state.totalBytesRetired + state.bufferPos + length;
uint result = 0;
do
{
// field=1, type=varint = tag of 8
if (ParsingPrimitives.ParseTag(ref buffer, ref state) == 8)
{
result = ParsingPrimitives.ParseRawVarint32(ref buffer, ref state);
}
else
{
ParsingPrimitivesMessages.SkipLastField(ref buffer, ref state);
}
}while (state.totalBytesRetired + state.bufferPos < finalBufferPos);
return(result);
}
/// <summary>
/// Parses the next tag.
/// If the end of logical stream was reached, an invalid tag of 0 is returned.
/// </summary>
public static uint ParseTag(ref ReadOnlySpan <byte> buffer, ref ParserInternalState state)
{
// The "nextTag" logic is there only as an optimization for reading non-packed repeated / map
// fields and is strictly speaking not necessary.
// TODO(jtattermusch): look into simplifying the ParseTag logic.
if (state.hasNextTag)
{
state.lastTag = state.nextTag;
state.hasNextTag = false;
return(state.lastTag);
}
// Optimize for the incredibly common case of having at least two bytes left in the buffer,
// and those two bytes being enough to get the tag. This will be true for fields up to 4095.
if (state.bufferPos + 2 <= state.bufferSize)
{
int tmp = buffer[state.bufferPos++];
if (tmp < 128)
{
state.lastTag = (uint)tmp;
}
else
{
int result = tmp & 0x7f;
if ((tmp = buffer[state.bufferPos++]) < 128)
{
result |= tmp << 7;
state.lastTag = (uint)result;
}
else
{
// Nope, rewind and go the potentially slow route.
state.bufferPos -= 2;
state.lastTag = ParsingPrimitives.ParseRawVarint32(ref buffer, ref state);
}
}
}
else
{
if (SegmentedBufferHelper.IsAtEnd(ref buffer, ref state))
{
state.lastTag = 0;
return(0);
}
state.lastTag = ParsingPrimitives.ParseRawVarint32(ref buffer, ref state);
}
if (WireFormat.GetTagFieldNumber(state.lastTag) == 0)
{
// If we actually read a tag with a field of 0, that's not a valid tag.
throw InvalidProtocolBufferException.InvalidTag();
}
return(state.lastTag);
}
internal static uint?ReadUInt32Wrapper(ref ReadOnlySpan <byte> buffer, ref ParserInternalState state)
{
// field=1, type=varint = tag of 8
const int expectedTag = 8;
// length:1 + tag:1 + value:10(varint64-max) = 12 bytes
// Value can be 64 bits for negative integers
if (state.bufferPos + 12 <= state.bufferSize)
{
// The entire wrapper message is already contained in `buffer`.
int pos0 = state.bufferPos;
int length = buffer[state.bufferPos++];
if (length == 0)
{
return(0);
}
// Length will always fit in a single byte.
if (length >= 128)
{
state.bufferPos = pos0;
return(ReadUInt32WrapperSlow(ref buffer, ref state));
}
int finalBufferPos = state.bufferPos + length;
if (buffer[state.bufferPos++] != expectedTag)
{
state.bufferPos = pos0;
return(ReadUInt32WrapperSlow(ref buffer, ref state));
}
var result = ParsingPrimitives.ParseRawVarint32(ref buffer, ref state);
// Verify this message only contained a single field.
if (state.bufferPos != finalBufferPos)
{
state.bufferPos = pos0;
return(ReadUInt32WrapperSlow(ref buffer, ref state));
}
return(result);
}
else
{
return(ReadUInt32WrapperSlow(ref buffer, ref state));
}
}
public int ReadLength()
{
return((int)ParsingPrimitives.ParseRawVarint32(ref buffer, ref state));
}
public int ReadSInt32()
{
return(ParsingPrimitives.DecodeZigZag32(ParsingPrimitives.ParseRawVarint32(ref buffer, ref state)));
}
public int ReadEnum()
{
// Currently just a pass-through, but it's nice to separate it logically from WriteInt32.
return((int)ParsingPrimitives.ParseRawVarint32(ref buffer, ref state));
}
public uint ReadUInt32()
{
return(ParsingPrimitives.ParseRawVarint32(ref buffer, ref state));
}