ArchiSteamFarm/ArchiSteamFarm/ConcurrentHashSet.cs

/*
    _                _      _  ____   _                           _____
   / \    _ __  ___ | |__  (_)/ ___| | |_  ___   __ _  _ __ ___  |  ___|__ _  _ __  _ __ ___
  / _ \  | '__|/ __|| '_ \ | |\___ \ | __|/ _ \ / _` || '_ ` _ \ | |_  / _` || '__|| '_ ` _ \
 / ___ \ | |  | (__ | | | || | ___) || |_|  __/| (_| || | | | | ||  _|| (_| || |   | | | | | |
/_/   \_\|_|   \___||_| |_||_||____/  \__|\___| \__,_||_| |_| |_||_|   \__,_||_|   |_| |_| |_|

 Copyright 2015-2017 Łukasz "JustArchi" Domeradzki
 Contact: JustArchi@JustArchi.net

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0
					
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.

*/

using System.Collections;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;

namespace ArchiSteamFarm {
	internal sealed class ConcurrentHashSet<T> : IReadOnlyCollection<T>, ISet<T> {
		public int Count => BackingCollection.Count;
		public bool IsReadOnly => false;

		private readonly ConcurrentDictionary<T, bool> BackingCollection = new ConcurrentDictionary<T, bool>();

		public bool Add(T item) => BackingCollection.TryAdd(item, true);
		public void Clear() => BackingCollection.Clear();
		public bool Contains(T item) => BackingCollection.ContainsKey(item);
		public void CopyTo(T[] array, int arrayIndex) => BackingCollection.Keys.CopyTo(array, arrayIndex);

		public void ExceptWith(IEnumerable<T> other) {
			foreach (T item in other) {
				Remove(item);
			}
		}

		public IEnumerator<T> GetEnumerator() => BackingCollection.Keys.GetEnumerator();

		public void IntersectWith(IEnumerable<T> other) {
			ICollection<T> collection = other as ICollection<T> ?? other.ToList();
			foreach (T item in this.Where(item => !collection.Contains(item))) {
				Remove(item);
			}
		}

		public bool IsProperSubsetOf(IEnumerable<T> other) {
			ICollection<T> collection = other as ICollection<T> ?? other.ToList();
			return (collection.Count != Count) && IsSubsetOf(collection);
		}

		public bool IsProperSupersetOf(IEnumerable<T> other) {
			ICollection<T> collection = other as ICollection<T> ?? other.ToList();
			return (collection.Count != Count) && IsSupersetOf(collection);
		}

		public bool IsSubsetOf(IEnumerable<T> other) {
			ICollection<T> collection = other as ICollection<T> ?? other.ToList();
			return this.AsParallel().All(collection.Contains);
		}

		public bool IsSupersetOf(IEnumerable<T> other) => other.AsParallel().All(Contains);
		public bool Overlaps(IEnumerable<T> other) => other.AsParallel().Any(Contains);
		public bool Remove(T item) => BackingCollection.TryRemove(item, out _);

		public bool SetEquals(IEnumerable<T> other) {
			ICollection<T> collection = other as ICollection<T> ?? other.ToList();
			return (collection.Count == Count) && collection.AsParallel().All(Contains);
		}

		public void SymmetricExceptWith(IEnumerable<T> other) {
			ICollection<T> collection = other as ICollection<T> ?? other.ToList();

			HashSet<T> removed = new HashSet<T>();
			foreach (T item in collection.Where(Contains)) {
				removed.Add(item);
				Remove(item);
			}

			foreach (T item in collection.Where(item => !removed.Contains(item))) {
				Add(item);
			}
		}

		public void UnionWith(IEnumerable<T> other) {
			foreach (T otherElement in other) {
				Add(otherElement);
			}
		}

		void ICollection<T>.Add(T item) => Add(item);
		IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();

		// We use Count() and not Any() because we must ensure full loop pass
		internal bool AddRange(IEnumerable<T> items) => items.Count(Add) > 0;

		// We use Count() and not Any() because we must ensure full loop pass
		internal bool RemoveRange(IEnumerable<T> items) => items.Count(Remove) > 0;

		internal bool ReplaceIfNeededWith(ICollection<T> other) {
			if (SetEquals(other)) {
				return false;
			}

			ReplaceWith(other);
			return true;
		}

		internal void ReplaceWith(IEnumerable<T> other) {
			BackingCollection.Clear();
			foreach (T item in other) {
				BackingCollection[item] = true;
			}
		}
	}
}