BidirectionalDictionary.cs

#nullable enable
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;

namespace TooManyExtensions
{
	public class BidirectionalDictionary<T1, T2> : IEnumerable<KeyValuePair<T1, T2>> where T1 : notnull where T2 : notnull
	{
		public Dictionary<T1, T2> Forward { get; } = new();
		public Dictionary<T2, T1> Reverse { get; } = new();
		
		public void Add(T1 t1, T2 t2)
		{
			Forward[t1] = t2;
			Reverse[t2] = t1;
		}
		
		public void Remove(T1 t1)
		{
			Reverse.Remove(Forward[t1]);
			Forward.Remove(t1);
		}
		
		public void Remove(T2 t2)
		{
			Forward.Remove(Reverse[t2]);
			Reverse.Remove(t2);
		}
		
		public bool TryGetValue(T1 t1, [NotNullWhen(true)] out T2? t2) => Forward.TryGetValue(t1, out t2);
		public bool TryGetValue(T2 t2, [NotNullWhen(true)] out T1? t1) => Reverse.TryGetValue(t2, out t1);
		
		public T2 this[T1 t1]
		{
			get => Forward[t1];
			set
			{
				Forward[t1] = value;
				Reverse[value] = t1;
			}
		}
		
		public T1 this[T2 t2]
		{
			get => Reverse[t2];
			set
			{
				Reverse[t2] = value;
				Forward[value] = t2;
			}
		}
		
		public void Clear()
		{
			Forward.Clear();
			Reverse.Clear();
		}
		
		public bool ContainsKey(T1 t1) => Forward.ContainsKey(t1);
		public bool ContainsKey(T2 t2) => Reverse.ContainsKey(t2);
		
		public int Count => Forward.Count;
		
		public IEnumerable<T1> Keys => Forward.Keys;
		public IEnumerable<T2> Values => Forward.Values;
		
		public IEnumerator<KeyValuePair<T1, T2>> GetEnumerator() => Forward.GetEnumerator();
		
		public bool Remove(KeyValuePair<T1, T2> kvp)
		{
			if (Forward.Remove(kvp.Key) && Reverse.Remove(kvp.Value))
			{
				return true;
			}
			return false;
		}
		
		public bool Remove(KeyValuePair<T2, T1> kvp)
		{
			if (Reverse.Remove(kvp.Key) && Forward.Remove(kvp.Value))
			{
				return true;
			}
			return false;
		}
		
		public bool TryAdd(T1 t1, T2 t2)
		{
			if (Forward.TryAdd(t1, t2))
			{
				Reverse.TryAdd(t2, t1);
				return true;
			}
			return false;
		}
		
		public bool TryRemove(T1 t1, [NotNullWhen(true)] out T2? t2)
		{
			if (ContainsKey(t1))
			{
				t2 = Forward[t1];
				Forward.Remove(t1);
				Reverse.Remove(t2);
				return true;
			}
			t2 = default;
			return false;
		}
		
		public bool TryRemove(T2 t2, [NotNullWhen(true)] out T1? t1)
		{
			if (ContainsKey(t2))
			{
				t1 = Reverse[t2];
				Forward.Remove(t1);
				Reverse.Remove(t2);
				return true;
			}
			t1 = default;
			return false;
		}
		
		IEnumerator IEnumerable.GetEnumerator()
		{
			return GetEnumerator();
		}
	}
}