|
static private InvalidTag ( ) : |
||
| return | ||
/// <summary>
/// Reads a field tag, returning the tag of 0 for "end of stream".
/// </summary>
/// <remarks>
/// If this method returns 0, it doesn't necessarily mean the end of all
/// the data in this CodedInputStream; it may be the end of the logical stream
/// for an embedded message, for example.
/// </remarks>
/// <returns>The next field tag, or 0 for end of stream. (0 is never a valid tag.)</returns>
public uint ReadTag()
{
if (hasNextTag)
{
lastTag = nextTag;
hasNextTag = false;
return(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 (bufferPos + 2 <= bufferSize)
{
int tmp = buffer[bufferPos++];
if (tmp < 128)
{
lastTag = (uint)tmp;
}
else
{
int result = tmp & 0x7f;
if ((tmp = buffer[bufferPos++]) < 128)
{
result |= tmp << 7;
lastTag = (uint)result;
}
else
{
// Nope, rewind and go the potentially slow route.
bufferPos -= 2;
lastTag = ReadRawVarint32();
}
}
}
else
{
if (IsAtEnd)
{
lastTag = 0;
return(0);
}
lastTag = ReadRawVarint32();
}
if (WireFormat.GetTagFieldNumber(lastTag) == 0)
{
// If we actually read a tag with a field of 0, that's not a valid tag.
throw InvalidProtocolBufferException.InvalidTag();
}
if (ReachedLimit)
{
return(0);
}
return(lastTag);
}
/// <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);
}
/// <summary>
/// Attempts to read a field tag, returning false if we have reached the end
/// of the input data.
/// </summary>
/// <param name="fieldTag">The 'tag' of the field (id * 8 + wire-format)</param>
/// <returns>true if the next fieldTag was read</returns>
public bool ReadTag(out uint fieldTag)
{
if (hasNextTag)
{
fieldTag = nextTag;
lastTag = fieldTag;
hasNextTag = false;
return(true);
}
// 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 (bufferPos + 2 <= bufferSize)
{
int tmp = buffer[bufferPos++];
if (tmp < 128)
{
fieldTag = (uint)tmp;
}
else
{
int result = tmp & 0x7f;
if ((tmp = buffer[bufferPos++]) < 128)
{
result |= tmp << 7;
fieldTag = (uint)result;
}
else
{
// Nope, rewind and go the potentially slow route.
bufferPos -= 2;
fieldTag = ReadRawVarint32();
}
}
}
else
{
if (IsAtEnd)
{
fieldTag = 0;
lastTag = fieldTag;
return(false);
}
fieldTag = ReadRawVarint32();
}
lastTag = fieldTag;
if (lastTag == 0)
{
// If we actually read zero, that's not a valid tag.
throw InvalidProtocolBufferException.InvalidTag();
}
return(true);
}
