public static DateTimeWindow Parse(string value)
{
DateTimeWindow result;
if (DateTimeWindow.TryParse(value, out result))
{
return(result);
}
throw new FormatException("Invalid window format: '" + value + "'.");
}
private static void AppendWindowsBetween(DateTime start, DateTime end, DateTimeRange[] ranges, int rangeIndex, ICollection <DateTimeWindow> result)
{
if (start >= end || rangeIndex >= ranges.Length)
{
return;
}
var currentRange = ranges[rangeIndex];
var window = DateTimeWindow.Find(start, currentRange);
if (window.Start < start)
{
if (window.Start + currentRange <= end)
{
window += currentRange;
// Append buckets with a smaller range that are required before this one
AppendWindowsBetween(start, window.Start.Value, ranges, rangeIndex + 1, result);
}
else
{
// This bucket is too large to fit in the interval, try with a smaller range
AppendWindowsBetween(start, end, ranges, rangeIndex + 1, result);
return;
}
}
// Append buckets of this size until no more fit
var windowEnd = window.Start + currentRange;
while (windowEnd <= end)
{
result.Add(window);
window += currentRange;
windowEnd = windowEnd + currentRange;
}
if (window.Start < end)
{
// Append smaller buckets to fill the gap between bucket.Timestamp and end
AppendWindowsBetween(window.Start.Value, end, ranges, rangeIndex + 1, result);
}
}
public static IReadOnlyCollection <DateTimeWindow> GetWindowsBetween(DateTime start, DateTime end, IReadOnlyCollection <DateTimeRange> granularities, EdgeMode edges = EdgeMode.Shrink)
{
var result = new List <DateTimeWindow>();
if (start >= end || granularities.Count == 0)
{
return(result);
}
var ranges = granularities.OrderByDescending(g => g).ToArray();
AppendWindowsBetween(start, end, ranges, 0, result);
// In 'Grow' mode, ensure the returned list of buckets **at least** covers the start and end times
if (edges == EdgeMode.Grow)
{
var smallestRange = ranges.Last();
if (result.Count == 0 || result[0].start > start)
{
// No buckets fit, or start bucket starts too late.
// Add the smallest bucket starting before the start time
var startWindow = DateTimeWindow.Find(start, smallestRange);
result.Insert(0, startWindow);
}
var lastWindow = result.Last();
if (lastWindow.end < end)
{
// End bucket finishes too early.
// Add the smallest bucket starting before the end time
var finalWindow = DateTimeWindow.Find(end, smallestRange);
result.Add(finalWindow);
}
}
return(result.AsReadOnly());
}
public static bool TryParse(string value, out DateTimeWindow result)
{
if (string.IsNullOrEmpty(value))
{
throw new ArgumentNullException("value");
}
var match = StringFormatExpression.Match(value);
if (!match.Success)
{
result = null;
return(false);
}
var startExpr = match.Groups["start"].Value;
DateTime?start = null;
if (startExpr != "*" && !DateMath.TryEvaluate(startExpr, out start))
{
result = null;
return(false);
}
var endExpr = match.Groups["end"].Value;
DateTime?end = null;
if (endExpr != "*" && !DateMath.TryEvaluate(endExpr, out end))
{
result = null;
return(false);
}
result = new DateTimeWindow(start, end);
return(true);
}
