/// <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));
}
}
/// <summary>
/// Parses the next <see cref="BList"/> from the reader.
/// </summary>
/// <param name="reader">The reader to parse from.</param>
/// <param name="cancellationToken"></param>
/// <returns>The parsed <see cref="BList"/>.</returns>
/// <exception cref="InvalidBencodeException{BList}">Invalid bencode.</exception>
public override async ValueTask <BList> ParseAsync(PipeBencodeReader reader, CancellationToken cancellationToken = default)
{
if (reader == null)
{
throw new ArgumentNullException(nameof(reader));
}
var startPosition = reader.Position;
// Lists must start with 'l'
if (await reader.ReadCharAsync(cancellationToken).ConfigureAwait(false) != 'l')
{
throw InvalidBencodeException <BList> .UnexpectedChar('l', reader.PreviousChar, startPosition);
}
var list = new BList();
// Loop until next character is the end character 'e' or end of stream
while (await reader.PeekCharAsync(cancellationToken).ConfigureAwait(false) != 'e' &&
await reader.PeekCharAsync(cancellationToken).ConfigureAwait(false) != default)
{
// Decode next object in stream
var bObject = await BencodeParser.ParseAsync(reader, cancellationToken).ConfigureAwait(false);
list.Add(bObject);
}
if (await reader.ReadCharAsync(cancellationToken).ConfigureAwait(false) != 'e')
{
throw InvalidBencodeException <BList> .MissingEndChar(startPosition);
}
return(list);
}
/// <summary>
/// Parses the next <see cref="BDictionary"/> and its contained keys and values from the reader.
/// </summary>
/// <param name="reader">The reader to parse from.</param>
/// <param name="cancellationToken"></param>
/// <returns>The parsed <see cref="BDictionary"/>.</returns>
/// <exception cref="InvalidBencodeException{BDictionary}">Invalid bencode.</exception>
public override async ValueTask <BDictionary> ParseAsync(PipeBencodeReader reader, CancellationToken cancellationToken = default)
{
if (reader == null)
{
throw new ArgumentNullException(nameof(reader));
}
var startPosition = reader.Position;
// Dictionaries must start with 'd'
if (await reader.ReadCharAsync(cancellationToken).ConfigureAwait(false) != 'd')
{
throw InvalidBencodeException <BDictionary> .UnexpectedChar('d', reader.PreviousChar, startPosition);
}
var dictionary = new BDictionary();
// Loop until next character is the end character 'e' or end of stream
while (await reader.PeekCharAsync(cancellationToken).ConfigureAwait(false) != 'e' &&
await reader.PeekCharAsync(cancellationToken).ConfigureAwait(false) != default)
{
BString key;
try
{
// Decode next string in stream as the key
key = await BencodeParser.ParseAsync <BString>(reader, cancellationToken).ConfigureAwait(false);
}
catch (BencodeException ex)
{
throw InvalidException("Could not parse dictionary key. Keys must be strings.", ex, startPosition);
}
IBObject value;
try
{
// Decode next object in stream as the value
value = await BencodeParser.ParseAsync(reader, cancellationToken).ConfigureAwait(false);
}
catch (BencodeException ex)
{
throw InvalidException($"Could not parse dictionary value for the key '{key}'. There needs to be a value for each key.", ex, startPosition);
}
if (dictionary.ContainsKey(key))
{
throw InvalidException($"The dictionary already contains the key '{key}'. Duplicate keys are not supported.", startPosition);
}
dictionary.Add(key, value);
}
if (await reader.ReadCharAsync(cancellationToken).ConfigureAwait(false) != 'e')
{
throw InvalidBencodeException <BDictionary> .MissingEndChar(startPosition);
}
return(dictionary);
}
/// <summary>
/// Parses the next <see cref="BNumber"/> from the reader.
/// </summary>
/// <param name="reader">The reader to parse from.</param>
/// <param name="cancellationToken"></param>
/// <returns>The parsed <see cref="BNumber"/>.</returns>
/// <exception cref="InvalidBencodeException{BNumber}">Invalid bencode.</exception>
/// <exception cref="UnsupportedBencodeException{BNumber}">The bencode is unsupported by this library.</exception>
public override async ValueTask <BNumber> ParseAsync(PipeBencodeReader reader, CancellationToken cancellationToken = default)
{
if (reader == null)
{
throw new ArgumentNullException(nameof(reader));
}
var startPosition = reader.Position;
// Numbers must start with 'i'
if (await reader.ReadCharAsync(cancellationToken).ConfigureAwait(false) != 'i')
{
throw InvalidBencodeException <BNumber> .UnexpectedChar('i', reader.PreviousChar, startPosition);
}
using var memoryOwner = MemoryPool <char> .Shared.Rent(BNumber.MaxDigits);
var digits = memoryOwner.Memory;
var digitCount = 0;
for (var c = await reader.ReadCharAsync(cancellationToken).ConfigureAwait(false);
c != default && c != 'e';
c = await reader.ReadCharAsync(cancellationToken).ConfigureAwait(false))
{
digits.Span[digitCount++] = c;
}
if (digitCount == 0)
{
throw NoDigitsException(startPosition);
}
// Last read character should be 'e'
if (reader.PreviousChar != 'e')
{
throw InvalidBencodeException <BNumber> .MissingEndChar(startPosition);
}
return(ParseNumber(digits.Span.Slice(0, digitCount), startPosition));
}
public async Task CanReadAsyncBeforeWrite()
{
var bytes = Encoding.UTF8.GetBytes("abc").AsMemory();
var(reader, writer) = new Pipe();
var bencodeReader = new PipeBencodeReader(reader);
var readTask = bencodeReader.ReadCharAsync();
await writer.WriteAsync(bytes.Slice(0, 2));
writer.Complete();
var c = await readTask;
c.Should().Be('a');
}
