internal static T Read <T>(ref ParseContext ctx, FieldCodec <T> codec)
{
int length = ctx.ReadLength();
int oldLimit = SegmentedBufferHelper.PushLimit(ref ctx.state, length);
uint tag;
T value = codec.DefaultValue;
while ((tag = ctx.ReadTag()) != 0)
{
if (tag == codec.Tag)
{
value = codec.Read(ref ctx);
}
else
{
ParsingPrimitivesMessages.SkipLastField(ref ctx.buffer, ref ctx.state);
}
}
ParsingPrimitivesMessages.CheckReadEndOfStreamTag(ref ctx.state);
SegmentedBufferHelper.PopLimit(ref ctx.state, oldLimit);
return(value);
}
/// <summary>
/// Discards the current limit, returning the previous limit.
/// </summary>
internal void PopLimit(int oldLimit)
{
SegmentedBufferHelper.PopLimit(ref state, oldLimit);
}
public static KeyValuePair <TKey, TValue> ReadMapEntry <TKey, TValue>(ref ParseContext ctx, MapField <TKey, TValue> .Codec codec)
{
int length = ParsingPrimitives.ParseLength(ref ctx.buffer, ref ctx.state);
if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
{
throw InvalidProtocolBufferException.RecursionLimitExceeded();
}
int oldLimit = SegmentedBufferHelper.PushLimit(ref ctx.state, length);
++ctx.state.recursionDepth;
TKey key = codec.KeyCodec.DefaultValue;
TValue value = codec.ValueCodec.DefaultValue;
uint tag;
while ((tag = ctx.ReadTag()) != 0)
{
if (tag == codec.KeyCodec.Tag)
{
key = codec.KeyCodec.Read(ref ctx);
}
else if (tag == codec.ValueCodec.Tag)
{
value = codec.ValueCodec.Read(ref ctx);
}
else
{
SkipLastField(ref ctx.buffer, ref ctx.state);
}
}
// Corner case: a map entry with a key but no value, where the value type is a message.
// Read it as if we'd seen input with no data (i.e. create a "default" message).
if (value == null)
{
if (ctx.state.CodedInputStream != null)
{
// the decoded message might not support parsing from ParseContext, so
// we need to allow fallback to the legacy MergeFrom(CodedInputStream) parsing.
value = codec.ValueCodec.Read(new CodedInputStream(ZeroLengthMessageStreamData));
}
else
{
ParseContext.Initialize(new ReadOnlySequence <byte>(ZeroLengthMessageStreamData), out ParseContext zeroLengthCtx);
value = codec.ValueCodec.Read(ref zeroLengthCtx);
}
}
CheckReadEndOfStreamTag(ref ctx.state);
// Check that we've read exactly as much data as expected.
if (!SegmentedBufferHelper.IsReachedLimit(ref ctx.state))
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
--ctx.state.recursionDepth;
SegmentedBufferHelper.PopLimit(ref ctx.state, oldLimit);
return(new KeyValuePair <TKey, TValue>(key, value));
}
