/// <summary>
/// Parses the next <see cref="BString"/> from the reader.
/// </summary>
/// <param name="reader">The reader to parse from.</param>
/// <param name="cancellationToken"></param>
/// <returns>The parsed <see cref="BString"/>.</returns>
/// <exception cref="InvalidBencodeException{BString}">Invalid bencode.</exception>
/// <exception cref="UnsupportedBencodeException{BString}">The bencode is unsupported by this library.</exception>
public override async ValueTask <BString> ParseAsync(PipeBencodeReader reader, CancellationToken cancellationToken = default)
{
if (reader == null)
{
throw new ArgumentNullException(nameof(reader));
}
var startPosition = reader.Position;
using (var memoryOwner = MemoryPool <char> .Shared.Rent(BString.LengthMaxDigits))
{
var lengthString = memoryOwner.Memory;
var lengthStringCount = 0;
for (var c = await reader.ReadCharAsync(cancellationToken).ConfigureAwait(false);
c != default && c.IsDigit();
c = await reader.ReadCharAsync(cancellationToken).ConfigureAwait(false))
{
EnsureLengthStringBelowMaxLength(lengthStringCount, startPosition);
lengthString.Span[lengthStringCount++] = c;
}
EnsurePreviousCharIsColon(reader.PreviousChar, reader.Position);
var stringLength = ParseStringLength(lengthString.Span, lengthStringCount, startPosition);
var bytes = new byte[stringLength];
var bytesRead = await reader.ReadAsync(bytes, cancellationToken).ConfigureAwait(false);
EnsureExpectedBytesRead(bytesRead, stringLength, startPosition);
return(new BString(bytes, Encoding));
}
}
public async Task CanReadLessThanRequested()
{
var bytes = Encoding.UTF8.GetBytes("abc").AsMemory();
var(reader, writer) = new Pipe();
var bencodeReader = new PipeBencodeReader(reader);
await writer.WriteAsync(bytes.Slice(0, 1));
var buffer = new byte[bytes.Length];
var readTask = bencodeReader.ReadAsync(buffer);
await writer.WriteAsync(bytes.Slice(1, 1));
writer.Complete();
var bytesRead = await readTask;
bytesRead.Should().Be(2);
buffer[0].Should().Be((byte)'a');
buffer[1].Should().Be((byte)'b');
buffer[2].Should().Be(default);
internal static Task SkipBytesAsync(this PipeBencodeReader reader, int length)
{
return(reader.ReadAsync(new byte[length]).AsTask());
}