/// <summary>
/// Searches for the given object.
/// </summary>
/// <param name = "toFind">The object to search for.</param>
/// <param name = "range">The range in which to search.</param>
/// <param name = "indexOperations">Operations that can be done on an indexer.</param>
/// <returns>The found object, or it's nearest matches.</returns>
public static BinarySearchResult <TObject> Search(
TObject toFind,
Interval <TIndex> range,
IndexerDelegates <TObject, TIndex> indexOperations)
{
// Make sure start and end of range are valid.
// TODO: This is only necessary the first call of the recursion. Implementing the search as a loop could be more performant.
range = new Interval <TIndex>(
indexOperations.GetNearestIndex(range.Start),
indexOperations.GetNearestIndex(range.End));
// Get object near the center of the range.
TIndex center = indexOperations.GetNearestIndex(range.Center);
TObject centerObject = indexOperations.GetByIndex(center);
// Check whether desired object was found.
int orderToCenter = toFind.CompareTo(centerObject);
// See whether finished.
bool isObjectFound = orderToCenter == 0;
bool hasNoMoreObjects = IndexComparer.Equals(center, range.Start) || IndexComparer.Equals(center, range.End);
bool isFinished = isObjectFound || hasNoMoreObjects;
if (!isFinished)
{
// Split interval in the middle.
Interval <TIndex> smaller, bigger;
range.Split(center, SplitOption.Both, out smaller, out bigger);
// Continue recursively in the range in which the object lies.
Interval <TIndex> inRange = orderToCenter > 0 ? bigger : smaller;
return(Search(toFind, inRange, indexOperations));
}
else
{
TObject smaller = indexOperations.GetByIndex(range.Start);
TObject bigger = indexOperations.GetByIndex(range.End);
// Find the desired object.
TObject foundObject = default(TObject);
if (isObjectFound)
{
foundObject = centerObject;
}
else
{
if (toFind.CompareTo(smaller) == 0)
{
isObjectFound = true;
foundObject = smaller;
}
else if (toFind.CompareTo(bigger) == 0)
{
isObjectFound = true;
foundObject = bigger;
}
}
// Return result.
bool isObjectInRange = toFind.CompareTo(smaller) >= 0 && toFind.CompareTo(bigger) <= 0;
return(new BinarySearchResult <TObject>
{
IsObjectInRange = isObjectInRange,
IsObjectFound = isObjectFound,
Found = isObjectFound ? new BinarySearchResult <TObject> .FoundResult(foundObject) : null,
NotFound = isObjectFound || !isObjectInRange ? null : new BinarySearchResult <TObject> .NotFoundResult(smaller, bigger)
});
}
}
