/// <inheritdoc/>
public override DateTime?GetTimeOfNearestMessage(DateTime time, NearestMessageType snappingBehavior)
{
int index = IndexHelper.GetIndexForTime(time, this.data.Count, (idx) => this.data[idx].OriginatingTime, snappingBehavior);
return((index >= 0) ? this.data[index].OriginatingTime : null);
}
/// <summary> /// Gets the time of the nearest message to a specified time, on a specified stream. /// </summary> /// <param name="streamSource">The stream source specifying the stream of interest.</param> /// <param name="time">The time to find the nearest message to.</param> /// <param name="nearestMessageType">The type of nearest message to find.</param> /// <returns>The time of the nearest message, if one is found or null otherwise.</returns> internal DateTime?GetTimeOfNearestMessage(StreamSource streamSource, DateTime time, NearestMessageType nearestMessageType) => this.GetStreamProviderOrDefault(streamSource.StreamName) .GetTimeOfNearestMessage(time, nearestMessageType);
/// <inheritdoc/> public abstract DateTime?GetTimeOfNearestMessage(DateTime time, NearestMessageType snappingBehavior);
/// <summary>
/// Gets the index id corresponding to a specified time for
/// a collection of indices that are ordered by time.
/// </summary>
/// <param name="dateTime">The time to find the index for.</param>
/// <param name="count">The number of items in the index collection.</param>
/// <param name="timeAtIndex">A function that returns the time for a given index id.</param>
/// <param name="snappingBehavior">Timeline snapping behaviors.</param>
/// <returns>The index id closest to the specified time, using the specified interpolation style.</returns>
public static int GetIndexForTime(DateTime dateTime, int count, Func <int, DateTime> timeAtIndex, NearestMessageType snappingBehavior = NearestMessageType.Nearest)
{
// If there's only one point in the index, then return its index
if (count == 1)
{
return(0);
}
// Perform a binary search
// If no exact match, lo and hi indicate ticks that
// are right before and right after the time we're looking for.
SearchResult result = SearchIndex(dateTime, count, timeAtIndex);
if (result.ExactMatchFound)
{
return(result.ExactIndex);
}
return(snappingBehavior switch
{
NearestMessageType.Previous => result.LowIndex,
NearestMessageType.Next => result.HighIndex,
// o/w return the index of whichever point is closest to the current time
_ => (timeAtIndex(result.HighIndex) - dateTime) < (dateTime - timeAtIndex(result.LowIndex)) ? result.HighIndex : result.LowIndex,
});
