/// <summary>
/// Helper method to try to read next character from bound <see cref="PotentiallyAsyncReader{TValue}"/>, or throw if no more characters can be read.
/// </summary>
/// <typeparam name="TValue">The type of values that this reader produces.</typeparam>
/// <param name="reader">This <see cref="PotentiallyAsyncReader{TValue}"/>.</param>
/// <returns>A task which will return character read.</returns>
/// <exception cref="NullReferenceException">If this <see cref="PotentiallyAsyncReader{TValue}"/> is <c>null</c>.</exception>
/// <exception cref="EndOfStreamException">If no more characters could be read from the source.</exception>
public static async ValueTask <TValue> ReadNextAsync <TValue>(
this PotentiallyAsyncReader <TValue?> reader
)
where TValue : struct
{
return(await ArgumentValidator.ValidateNotNullReference(reader).TryReadNextAsync() ?? throw new EndOfStreamException());
}
/// <summary>
/// Helper method to try to read next value from this <see cref="PotentiallyAsyncReader{TValue}"/>, or throw if no more values can be read.
/// </summary>
/// <typeparam name="TValue">The type of values that this reader produces.</typeparam>
/// <param name="reader">This <see cref="PotentiallyAsyncReader{TValue}"/>.</param>
/// <param name="checker">Optional callback to check value. If it is supplied, this method will keep reading values until this callback returns <c>true</c>.</param>
/// <returns>A task which will return last value read.</returns>
/// <exception cref="NullReferenceException">If this <see cref="PotentiallyAsyncReader{TValue}"/> is <c>null</c>.</exception>
/// <exception cref="EndOfStreamException">If no more values could be read from the source.</exception>
public static async ValueTask <TValue> ReadUntilAsync <TValue>(
this PotentiallyAsyncReader <TValue?> reader,
Func <TValue, Boolean> checker
)
where TValue : struct
{
return(await reader.TryReadUntilAsync(checker) ?? throw new EndOfStreamException());
}
/// <summary>
/// Helper method to try to read next value from this <see cref="PotentiallyAsyncReader{TValue}"/> until suitable value has been read, or values will end.
/// </summary>
/// <typeparam name="TValue">The type of values that this reader produces.</typeparam>
/// <param name="reader">This <see cref="PotentiallyAsyncReader{TValue}"/>.</param>
/// <param name="checker">Optional callback to check value. If it is supplied, this method will keep reading values until this callback returns <c>true</c>.</param>
/// <returns>A task which will return last value read.</returns>
/// <exception cref="NullReferenceException">If this <see cref="PotentiallyAsyncReader{TValue}"/> is <c>null</c>.</exception>
public static async ValueTask <TValue?> TryReadUntilAsync <TValue>(
this PotentiallyAsyncReader <TValue?> reader,
Func <TValue, Boolean> checker
)
where TValue : struct
{
ArgumentValidator.ValidateNotNullReference(reader);
TValue?charRead;
do
{
charRead = await reader.TryReadNextAsync();
} while (charRead.HasValue && !(checker?.Invoke(charRead.Value) ?? true));
return(charRead);
}
/// <summary>
/// This helper method will make this <see cref="PotentiallyAsyncReader{TValue}"/> clear the underlying buffer of <see cref="StreamReaderWithResizableBuffer"/> becomes greater or equal to than given limit, until the <see cref="IDisposable.Dispose"/> method is called.
/// </summary>
/// <param name="reader">This <see cref="PotentiallyAsyncReader{TValue}"/>.</param>
/// <param name="source">The <see cref="StreamReaderWithResizableBuffer"/> to clear after each character read.</param>
/// <param name="maxCount">The maximum amount of bytes that can be seen in <paramref name="source"/>.</param>
/// <returns>The <see cref="IDisposable"/> to specify a segment of code which will cause underlying stream buffer to empty after each character read.</returns>
/// <exception cref="NullReferenceException">If this <see cref="PotentiallyAsyncReader{TValue}"/> is <c>null</c>.</exception>
public static IDisposable ClearStreamWhenStreamBufferTooBig <TValue>(
this PotentiallyAsyncReader <TValue> reader,
StreamReaderWithResizableBuffer source,
Int32 maxCount
)
{
GenericEventHandler <ReadCompletedEventArgs <TValue> > evtHandler = args =>
{
if (source.ReadBytesCount >= maxCount)
{
source.EraseReadBytesFromBuffer();
}
};
ArgumentValidator.ValidateNotNullReference(reader).ReadCompleted += evtHandler;
return(new UsingHelper(() =>
{
reader.ReadCompleted -= evtHandler;
source.EraseReadBytesFromBuffer();
}));
}
