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Two-way dictionaries
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
public class TwoWayDictionary<T1, T2> : ICollection<Tuple<T1, T2>>
{
private static Tuple<T1, T2> ToTuple(T1 item1, T2 item2)
{
return Tuple.Create(item1, item2);
}
private static Tuple<T1, T2> ToTuple(KeyValuePair<T1, T2> pair)
{
return ToTuple(pair.Key, pair.Value);
}
private static KeyValuePair<T1, T2> ToForwardPair(Tuple<T1, T2> tuple)
{
return new KeyValuePair<T1, T2>(tuple.Item1, tuple.Item2);
}
private static KeyValuePair<T2, T1> ToReversePair(Tuple<T1, T2> tuple)
{
return new KeyValuePair<T2, T1>(tuple.Item2, tuple.Item1);
}
private IDictionary<T1, T2> forward;
private IDictionary<T2, T1> reverse;
public int Count
{
get { return forward.Count; }
}
public bool IsReadOnly
{
get { return false; }
}
public TwoWayDictionary()
{
forward = new Dictionary<T1, T2>();
reverse = new Dictionary<T2, T1>();
}
public void Add(T1 item1, T2 item2)
{
forward.Add(item1, item2);
try
{
reverse.Add(item2, item1);
}
catch
{
forward.Remove(item1);
throw;
}
}
public void Add(Tuple<T1, T2> tuple)
{
Add(tuple.Item1, tuple.Item2);
}
public void Clear()
{
forward.Clear();
reverse.Clear();
}
public bool Contains(Tuple<T1, T2> tuple)
{
return forward.Contains(ToForwardPair(tuple));
}
public void CopyTo(Tuple<T1, T2>[] array, int arrayIndex)
{
foreach (Iterator<KeyValuePair<T1, T2>> pair in forward.Iterate())
{
array[arrayIndex + pair.Index] = ToTuple(pair.Value);
}
}
public bool Remove(Tuple<T1, T2> tuple)
{
if (forward.Remove(ToForwardPair(tuple)))
{
reverse.Remove(ToReversePair(tuple));
return true;
}
else
{
return false;
}
}
public T2 Forward(T1 item1)
{
return forward[item1];
}
public T1 Reverse(T2 item2)
{
return reverse[item2];
}
public IEnumerator<Tuple<T1, T2>> GetEnumerator()
{
return forward.Select(ToTuple).GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
}
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