private static IEnumerable <T> BinarySearch <T>(IList <T> index, BinarySearchDelegate <T> tester)
{
if (index.Count > 0)
{
return(BinarySearch(index, 0, index.Count - 1, tester));
}
else
{
return(new List <T>());
}
}
private static IEnumerable <T> ExtendMatchingRange <T>(IList <T> index, int knownMatchIndex, BinarySearchDelegate <T> tester, out int first, out int last)
{
if (index == null)
{
throw new ArgumentNullException("index");
}
if (tester == null)
{
throw new ArgumentNullException("tester");
}
if (knownMatchIndex < 0 || knownMatchIndex >= index.Count)
{
throw new ArgumentOutOfRangeException("knownMatchIndex");
}
first = knownMatchIndex;
last = knownMatchIndex;
while (first > 0 && tester(index[first - 1]) == 0)
{
--first;
}
while (last + 1 < index.Count && tester(index[last + 1]) == 0)
{
++last;
}
List <T> result = new List <T>();
for (int i = first; i <= last; ++i)
{
result.Add(index[i]);
}
return(result);
}
private static IEnumerable <T> ExtendMatchingRange <T>(IList <T> index, int knownMatchIndex, BinarySearchDelegate <T> tester)
{
int dummyFirst = 0;
int dummyLast = 0;
return(ExtendMatchingRange(index, knownMatchIndex, tester, out dummyFirst, out dummyLast));
}
/// <summary>
/// Finds all items in the specified range of the specified sorted list for which the
/// given tester returns 0.
/// </summary>
private static IEnumerable <T> BinarySearch <T>(IList <T> index, int first, int last, BinarySearchDelegate <T> tester)
{
if (index == null)
{
throw new ArgumentNullException("index");
}
if (tester == null)
{
throw new ArgumentNullException("tester");
}
if (first < 0)
{
throw new ArgumentOutOfRangeException("first");
}
if (last >= index.Count || last < first)
{
throw new ArgumentOutOfRangeException("last");
}
int middle = (first + last) / 2;
int middleTest = tester(index[middle]);
if (middleTest > 0)
{
if (middle > first)
{
return(BinarySearch(index, first, middle - 1, tester));
}
else
{
return(new List <T>());
}
}
else if (middleTest < 0)
{
if (last > middle)
{
return(BinarySearch(index, middle + 1, last, tester));
}
else
{
return(new List <T>());
}
}
else
{
return(ExtendMatchingRange(index, middle, tester));
}
}
