SegmentedHashSet.cs

Segmented Hashset Class

Useful for input or output buffer for use in parallel invoke operations where unique values are needed.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
public class SegmentedHashSet<T> : IEnumerable<T>
{
    private readonly IntHs<T>[] _array;
    private readonly int        _size;
    private          int        _length;
    public SegmentedHashSet(int length, int size)
    {
        _array = new IntHs<T>[4096];
        for (var i = 0; i < length; ++i)
            _array[i] = new IntHs<T>(size);
        _length = length;
        _size   = size;
    }
    public IEnumerator<T> GetEnumerator()
    {
        throw new NotImplementedException();
    }
    IEnumerator IEnumerable.GetEnumerator()
    {
        return GetEnumerator();
    }
    public void Add(T item, int index)
    {
        if (index >= _length)
            for (var i = _length; i <= index; ++i)
            {
                _array[i] = new IntHs<T>(_size);
                _length++;
            }
        if (!ContainedInArray(item))
            _array[index].Add(item);
    }
    private bool ContainedInArray(T item)
    {
        for (var i = 0; i < _length; ++i)
            if (_array[i].Contains(item))
                return true;
        return false;
    }
    public T[] CombineToArray()
    {
        var totalCount = 0;
        for (var i = 0; i < _length; ++i)
            totalCount += _array[i].Count;
        var ta  = new T[totalCount];
        var ptr = 0;
        for (var i = 0; i < _length; ++i)
        {
            var it = _array[i].ToArray();
            _array[i].Zero();
            for (var j = 0; j < it.Length; ++j)
                ta[ptr++] = it[j];
        }
        return ta;
    }
    [DebuggerDisplay("Count = {Count}")]
    internal class IntHs<T> : IEnumerable
    {
        private  Bucket[]             _buckets;
        internal IEqualityComparer<T> Comparer;
        public IntHs(int size) : this(size, null)
        {
        }
        public IntHs(int size, IEqualityComparer<T> comparer)
        {
            if (comparer == null)
                comparer = EqualityComparer<T>.Default;
            Comparer = comparer;
            _buckets = new Bucket[size];
            Count    = 0;
        }
        public int Count
        {
            get;
            private set;
        }
        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
        public void Zero()
        {
            _buckets = null;
            Count    = 0;
        }
        public bool Add(T item)
        {
            if (Count >= _buckets.Length)
                EnsureSize();
            var hashCode = Comparer.GetHashCode(item) & int.MaxValue;
            var apos     = FindEntry(item, hashCode).APos;
            if (apos != -1)
                return false;
            var pos = hashCode % _buckets.Length;
            if (_buckets[pos] == null)
                _buckets[pos] = new Bucket();
            _buckets[pos].Add(item);
            Count++;
            return true;
        }
        public T[] ToArray()
        {
            var newArray = new T[Count];
            using (var en = GetEnumerator())
            {
                var ptr = 0;
                while (en.MoveNext())
                {
                    var value = en.Current;
                    if (value == null)
                        break;
                    newArray[ptr++] = value;
                }
                return newArray;
            }
        }
        private (int APos, int BPos) FindEntry(T item, int hashCode)
        {
            if (Count == 0)
                return (-1, -1);
            var aPos = hashCode % _buckets.Length;
            var bPos = 0;
            if (_buckets[aPos] == null)
            {
                _buckets[aPos] = new Bucket();
                return (-1, -1);
            }
            foreach (var i in _buckets[aPos].Values)
            {
                if (Equals(i, item))
                    return (aPos, bPos);
                bPos++;
            }
            return (-1, -1);
        }
        private void EnsureSize()
        {
            var cArray = ToArray();
            _buckets = new Bucket[_buckets.Length + _buckets.Length / 4 * 3];
            foreach (var i in cArray)
            {
                var hashCode = Comparer.GetHashCode(i) & int.MaxValue;
                var pos      = hashCode % _buckets.Length;
                if (_buckets[pos] == null)
                    _buckets[pos] = new Bucket();
                _buckets[pos].Add(i);
            }
        }
        public bool Contains(T item)
        {
            var hashCode = Comparer.GetHashCode(item) & int.MaxValue;
            return FindEntry(item, hashCode).APos != -1;
        }
        public IEnumerator<T> GetEnumerator()
        {
            return GetEnum();
        }
        public IEnumerator<T> GetEnum()
        {
            for (var i = 0; i < _buckets.Length; i++)
                if (_buckets[i] != null)
                    for (var j = 0; j < _buckets[i].Count; ++j)
                        yield return _buckets[i].Values[j];
        }
        internal class Bucket
        {
            public int Count;
            public T[] Values;
            public Bucket()
            {
                Values = new T[1];
                Count  = 0;
            }
            public void Add(T item)
            {
                if (Count >= Values.Length)
                    Array.Resize(ref Values, Values.Length + 1);
                Values[Count++] = item;
            }
        }
    }
}