/// <summary>
/// Returns frames from a sequence as long as a specified condition is true.
/// </summary>
/// <param name="reader">The reader to get elements from.</param>
/// <param name="predicate">A function to test each source frame for a condition;
/// the second parameter of the function represents the index of the source frame in the scope of current operation.</param>
/// <returns>The enumeration that contains elements satisfying the predicate.
/// The reader position is on the first frame after this sequence. It is thus
/// possible to contiune with reading next frames.</returns>
public IEnumerable <RawCapture> TakeWhile(ICaptureFileReader reader, Func <RawCapture, int, bool> predicate)
{
var index = 0;
// read first frame if necessary...
if (reader.State == ReadingState.NotStarted)
{
reader.MoveNext();
}
if (reader.State == ReadingState.Finished)
{
yield break;
}
if (reader.State == ReadingState.Closed)
{
throw new InvalidOperationException("Cannot read from closed reader.");
}
do
{
if (predicate.Invoke(reader.Current, index))
{
yield return(reader.Current);
index++;
}
else
{
yield break;
}
} while (reader.MoveNext());
}
public static IObservable <RawCapture> CreateObservable(this ICaptureFileReader captureReader)
{
return(Observable.Create <RawCapture>((observer, cancellation) => Task.Factory.StartNew(
() =>
{
while (!cancellation.IsCancellationRequested && captureReader.GetNextFrame(out var rawFrame))
{
observer.OnNext(rawFrame);
}
observer.OnCompleted();
captureReader.Dispose();
})));
}
/// <summary>
/// Reads up to the specified <paramref name="count"/> of frames using the given <paramref name="reader"/>
/// </summary>
/// <param name="reader">The pcap reader.</param>
/// <param name="count">Number of frames to read.</param>
/// <returns>A collection of <see cref="RawFrame"/> objects.</returns>
public IEnumerable <RawCapture> Take(ICaptureFileReader reader, int count)
{
if (reader.State == ReadingState.Finished)
{
yield break;
}
if (reader.State == ReadingState.Closed)
{
throw new InvalidOperationException("Cannot read from closed reader.");
}
for (int i = 0; i < count; i++)
{
if (reader.GetNextFrame(out var frame, true))
{
yield return(frame);
}
else
{
yield break;
}
}
}
