/// <summary> Yields all elements that are between the elements in the specified sorted sequence. So basically, this is exclusion of the sequence from the range of the sequence. </summary>
/// <typeparam name="T"> The type of the elements. </typeparam>
/// <param name="sequence"> The sequence of the elements that are not yielded. </param>
/// <param name="increment"> A function specifying the next element given one. </param>
/// <param name="start"> The start of the range of all elements to yield. </param>
/// <param name="end"> The end of the range of all elements to yield. </param>
/// <param name="equalityComparer"> The equality comparer used for determining whether an element in the specified sequence matches that in the range. </param>
public static IEnumerable <T> RangeExcept <T>(this ISortedEnumerable <T> sequence, Func <T, T> increment, T start, T end, IEqualityComparer <T> equalityComparer = null)
{
Contract.Requires(sequence != null);
Contract.Requires(increment != null);
Contract.Requires(sequence.IsSorted(sequence.Comparer));
equalityComparer = equalityComparer ?? EqualityComparer <T> .Default;
T previouslyExcludedElement = start;
bool first = true;
foreach (var excludedElement in sequence.Concat(end))
{
foreach (var elementBelowExcludedElement in Range(previouslyExcludedElement, increment, excludedElement, equalityComparer, first))
{
if (equalityComparer.Equals(end, elementBelowExcludedElement))
{
yield break;
}
yield return(elementBelowExcludedElement);
}
if (equalityComparer.Equals(end, excludedElement))
{
yield break;
}
previouslyExcludedElement = excludedElement;
first = false;
}
}