public static unsafe T[] Distinct <T, TComp>(this T[] items)
where TComp : struct, IEqualityComparer <T>
{
var len = PowerOf2(items.Length * 2);
var buckets = stackalloc int[len];
var set = new StackHashSet <T, TComp>(items, buckets, len);
var resultIndexes = stackalloc int[items.Length];
var count = 0;
for (int i = 0; i < items.Length; i++)
{
if (!set.Add(items[i], i))
{
resultIndexes[count++] = i;
}
}
return(ToArray(items, resultIndexes, count));
}
public static T[] Distinct <T, TComp>(T[] items)
where TComp : struct, IEqualityComparer <T>
{
var len = StackHashSet.PowerOf2(items.Length * 2);
var buckets = new int[len];
var resultIndexes = new int[items.Length];
for (int i = 0; i < len; i++)
{
buckets[i] = -1;
}
var mask = len - 1;
var count = 0;
for (int i = 0; i < items.Length; i++)
{
var item = items[i];
var hash = default(TComp).GetHashCode(item) & mask;
while (true)
{
ref var b = ref buckets[hash];
if (b == -1)
{
resultIndexes[count] = i;
count++;
b = i;
break;
}
else if (default(TComp).Equals(item, items[b]))
{
break;
}
hash = (hash + StackHashSet.Skip) & mask;
}
}
public static unsafe T[] Except <T, TComp>(this T[] first, T[] second)
where TComp : struct, IEqualityComparer <T>
{
var len = PowerOf2(second.Length * 2);
var buckets = stackalloc int[len];
var set = new StackHashSet <T, TComp>(second, buckets, len);
set.MakeHashtTable();
var resultIndexes = stackalloc int[first.Length];
var count = 0;
for (int i = 0; i < first.Length; i++)
{
if (!set.Contains(first[i]))
{
resultIndexes[count++] = i;
}
}
return(ToArray(first, resultIndexes, count));
}
[Benchmark] public int[] Stack3() => StackHashSet.Distinct <int, IntComp>(data3);
