public void Search(IndexRange[] ranges, int index,
IndexRangeSearchApproximation approximation, IndexRangeSearchResult expectedResult)
{
var searchedIndex = ranges.Search(index, approximation);
Assert.Equal(searchedIndex, expectedResult);
}
/// <summary>
/// Searches an array for the range containing a given index. This method will try to
/// find the nearest range in case the given index is not covered within the ranges and
/// the value of <paramref name="approximation"/> is not <see cref="IndexRangeSearchApproximation.Exact"/>.
/// </summary>
/// <param name="ranges">The sorted ranges to search from.</param>
/// <param name="index">The index.</param>
/// <returns>
/// The index of the range if found, otherwise the index of the nearest left or right range depending
/// on the value of <paramref name="approximation"/> or -1 if it is <see cref="IndexRangeSearchApproximation.Exact"/>.
/// </returns>
public static IndexRangeSearchResult Search(this IReadOnlyList <IndexRange> ranges, int index,
IndexRangeSearchApproximation approximation = IndexRangeSearchApproximation.Exact)
{
var startIndex = 0;
var endIndex = ranges.Count - 1;
var approximationResult = -1;
while (startIndex <= endIndex)
{
var midIndex = (startIndex + endIndex) / 2;
var midRange = ranges[midIndex];
if (midRange.Contains(index))
{
return(new IndexRangeSearchResult(true, midIndex));
}
else if (midRange.FirstIndex < index)
{
startIndex = midIndex + 1;
if (approximation == IndexRangeSearchApproximation.NearestLeft)
{
approximationResult = midIndex;
}
}
else
{
endIndex = midIndex - 1;
if (approximation == IndexRangeSearchApproximation.NearestRight)
{
approximationResult = midIndex;
}
}
}
return(approximation == IndexRangeSearchApproximation.Exact
? new IndexRangeSearchResult(false, -1)
: new IndexRangeSearchResult(false, approximationResult));
}
