This collection class will maintain duplicates and insert sort order for the duplicate. The trick is to tag the items with a unique value
as they are inserted to maintain a stable sort order. Then we wrap it all up in an
ICollection interface.
public class SuperSortedSet<TValue> : ICollection<TValue>
{
private readonly SortedSet<Indexed<TValue>> _Container;
private int _Index = 0;
private IComparer<TValue> _Comparer;
public SuperSortedSet(IComparer<TValue> comparer)
{
_Comparer = comparer;
var c2 = new System.Linq.Comparer<Indexed<TValue>>((p0, p1) =>
{
var r = _Comparer.Compare(p0.Value, p1.Value);
if (r == 0)
{
if (p0.Index == -1
|| p1.Index == -1)
return 0;
return p0.Index.CompareTo(p1.Index);
}
else return r;
});
_Container = new SortedSet<Indexed<TValue>>(c2);
}
public IEnumerator<TValue> GetEnumerator() { return _Container.Select(p => p.Value).GetEnumerator(); }
IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); }
public void Add(TValue item) { _Container.Add(Indexed.Create(_Index++, item)); }
public void Clear() { _Container.Clear();}
public bool Contains(TValue item) { return _Container.Contains(Indexed.Create(-1,item)); }
public void CopyTo(TValue[] array, int arrayIndex)
{
foreach (var value in this)
{
if (arrayIndex >= array.Length)
{
throw new ArgumentException("Not enough space in array");
}
array[arrayIndex] = value;
arrayIndex++;
}
}
public bool Remove(TValue item) { return _Container.Remove(Indexed.Create(-1, item)); }
public int Count {
get { return _Container.Count; }
}
public bool IsReadOnly {
get { return false; }
}
}
a test class
[Fact]
public void ShouldWorkWithSuperSortedSet()
{
// Sort points according to X
var set = new SuperSortedSet<Point2D>
(new System.Linq.Comparer<Point2D>((p0, p1) => p0.X.CompareTo(p1.X)));
set.Add(new Point2D(9,10));
set.Add(new Point2D(1,25));
set.Add(new Point2D(11,-10));
set.Add(new Point2D(2,99));
set.Add(new Point2D(5,55));
set.Add(new Point2D(5,23));
set.Add(new Point2D(11,11));
set.Add(new Point2D(21,12));
set.Add(new Point2D(-1,76));
set.Add(new Point2D(16,21));
var xs = set.Select(p=>p.X).ToList();
xs.Should().BeInAscendingOrder();
xs.Count.Should()
.Be(10);
xs.ShouldBeEquivalentTo(new[]{-1,1,2,5,5,9,11,11,16,21});
set.Remove(new Point2D(5,55));
xs = set.Select(p=>p.X).ToList();
xs.Count.Should()
.Be(9);
xs.ShouldBeEquivalentTo(new[]{-1,1,2,5,9,11,11,16,21});
set.Remove(new Point2D(5,23));
xs = set.Select(p=>p.X).ToList();
xs.Count.Should()
.Be(8);
xs.ShouldBeEquivalentTo(new[]{-1,1,2,9,11,11,16,21});
set.Contains(new Point2D(11, 11))
.Should()
.BeTrue();
set.Contains(new Point2D(-1, 76))
.Should().BeTrue();
// Note that the custom compartor function ignores the Y value
set.Contains(new Point2D(-1, 66))
.Should().BeTrue();
set.Contains(new Point2D(27, 66))
.Should().BeFalse();
}
The tagging struct
public struct Indexed<T>
{
public int Index { get; private set; }
public T Value { get; private set; }
public Indexed(int index, T value) : this()
{
Index = index;
Value = value;
}
public override string ToString()
{
return "(Indexed: " + Index + ", " + Value.ToString () + " )";
}
}
public class Indexed
{
public static Indexed<T> Create<T>(int indexed, T value)
{
return new Indexed<T>(indexed, value);
}
}
The lambda comparer helper
public class Comparer<T> : IComparer<T>
{
private readonly Func<T, T, int> _comparer;
public Comparer(Func<T, T, int> comparer)
{
if (comparer == null)
throw new ArgumentNullException("comparer");
_comparer = comparer;
}
public int Compare(T x, T y)
{
return _comparer(x, y);
}
}
