/// <summary>
/// Helper method to try to peek next value from this <see cref="PeekablePotentiallyAsyncReader{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="PeekablePotentiallyAsyncReader{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 peeked.</returns>
/// <exception cref="NullReferenceException">If this <see cref="PeekablePotentiallyAsyncReader{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> PeekUntilAsync <TValue>(
this PeekablePotentiallyAsyncReader <TValue?> reader,
Func <TValue, Boolean> checker
)
where TValue : struct
{
return(await reader.TryPeekUntilAsync(checker) ?? throw new EndOfStreamException());
}
/// <summary>
/// Helper method to try to peek next value from this <see cref="PeekablePotentiallyAsyncReader{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="PeekablePotentiallyAsyncReader{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 peeked.</returns>
/// <exception cref="NullReferenceException">If this <see cref="PeekablePotentiallyAsyncReader{TValue}"/> is <c>null</c>.</exception>
public static async ValueTask <TValue?> TryPeekUntilAsync <TValue>(
this PeekablePotentiallyAsyncReader <TValue?> reader,
Func <TValue, Boolean> checker
)
where TValue : struct
{
ArgumentValidator.ValidateNotNullReference(reader);
var val = await reader.TryPeekAsync();
while (val.HasValue && !(checker?.Invoke(val.Value) ?? true))
{
await reader.TryReadNextAsync();
val = await reader.TryPeekAsync();
}
return(val);
}