private static void AssertReadFromParseContext(ReadOnlySequence <byte> input, ParseContextAssertAction assertAction, bool assertIsAtEnd)
{
ParseContext.Initialize(input, out ParseContext parseCtx);
assertAction(ref parseCtx);
if (assertIsAtEnd)
{
Assert.IsTrue(SegmentedBufferHelper.IsAtEnd(ref parseCtx.buffer, ref parseCtx.state));
}
}
/// <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);
}
private static void AssertReadFromParseContext(ReadOnlySequence <byte> input, ParseContextAssertAction assertAction, bool assertIsAtEnd)
{
// Check as ReadOnlySequence<byte>
ParseContext.Initialize(input, out ParseContext parseCtx);
assertAction(ref parseCtx);
if (assertIsAtEnd)
{
Assert.IsTrue(SegmentedBufferHelper.IsAtEnd(ref parseCtx.buffer, ref parseCtx.state));
}
// Check as ReadOnlySpan<byte>
ParseContext.Initialize(input.ToArray().AsSpan(), out ParseContext spanParseContext);
assertAction(ref spanParseContext);
if (assertIsAtEnd)
{
Assert.IsTrue(SegmentedBufferHelper.IsAtEnd(ref spanParseContext.buffer, ref spanParseContext.state));
}
}