I have created such a class, using C5 collection classes.
public class Mapper<K,T> : IEnumerable<T>
{
C5.TreeDictionary<K,T> KToTMap = new TreeDictionary<K,T>();
C5.HashDictionary<T,K> TToKMap = new HashDictionary<T,K>();
/// <summary>
/// Initializes a new instance of the Mapper class.
/// </summary>
public Mapper()
{
KToTMap = new TreeDictionary<K,T>();
TToKMap = new HashDictionary<T,K>();
}
public void Add(K key, T value)
{
KToTMap.Add(key, value);
TToKMap.Add(value, key);
}
public bool ContainsKey(K key)
{
return KToTMap.Contains(key);
}
public int Count
{
get { return KToTMap.Count; }
}
public K this[T obj]
{
get
{
return TToKMap[obj];
}
}
public T this[K obj]
{
get
{
return KToTMap[obj];
}
}
public IEnumerator<T> GetEnumerator()
{
return KToTMap.Values.GetEnumerator();
}
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
return KToTMap.Values.GetEnumerator();
}
}
OK, here is my attempt (building on Jon's - thanks), archived here and open for improvement :
/// <summary>
/// This is a dictionary guaranteed to have only one of each value and key.
/// It may be searched either by TFirst or by TSecond, giving a unique answer because it is 1 to 1.
/// </summary>
/// <typeparam name="TFirst">The type of the "key"</typeparam>
/// <typeparam name="TSecond">The type of the "value"</typeparam>
public class BiDictionaryOneToOne<TFirst, TSecond>
{
IDictionary<TFirst, TSecond> firstToSecond = new Dictionary<TFirst, TSecond>();
IDictionary<TSecond, TFirst> secondToFirst = new Dictionary<TSecond, TFirst>();
#region Exception throwing methods
/// <summary>
/// Tries to add the pair to the dictionary.
/// Throws an exception if either element is already in the dictionary
/// </summary>
/// <param name="first"></param>
/// <param name="second"></param>
public void Add(TFirst first, TSecond second)
{
if (firstToSecond.ContainsKey(first) || secondToFirst.ContainsKey(second))
throw new ArgumentException("Duplicate first or second");
firstToSecond.Add(first, second);
secondToFirst.Add(second, first);
}
/// <summary>
/// Find the TSecond corresponding to the TFirst first
/// Throws an exception if first is not in the dictionary.
/// </summary>
/// <param name="first">the key to search for</param>
/// <returns>the value corresponding to first</returns>
public TSecond GetByFirst(TFirst first)
{
TSecond second;
if (!firstToSecond.TryGetValue(first, out second))
throw new ArgumentException("first");
return second;
}
/// <summary>
/// Find the TFirst corresponing to the Second second.
/// Throws an exception if second is not in the dictionary.
/// </summary>
/// <param name="second">the key to search for</param>
/// <returns>the value corresponding to second</returns>
public TFirst GetBySecond(TSecond second)
{
TFirst first;
if (!secondToFirst.TryGetValue(second, out first))
throw new ArgumentException("second");
return first;
}
/// <summary>
/// Remove the record containing first.
/// If first is not in the dictionary, throws an Exception.
/// </summary>
/// <param name="first">the key of the record to delete</param>
public void RemoveByFirst(TFirst first)
{
TSecond second;
if (!firstToSecond.TryGetValue(first, out second))
throw new ArgumentException("first");
firstToSecond.Remove(first);
secondToFirst.Remove(second);
}
/// <summary>
/// Remove the record containing second.
/// If second is not in the dictionary, throws an Exception.
/// </summary>
/// <param name="second">the key of the record to delete</param>
public void RemoveBySecond(TSecond second)
{
TFirst first;
if (!secondToFirst.TryGetValue(second, out first))
throw new ArgumentException("second");
secondToFirst.Remove(second);
firstToSecond.Remove(first);
}
#endregion
#region Try methods
/// <summary>
/// Tries to add the pair to the dictionary.
/// Returns false if either element is already in the dictionary
/// </summary>
/// <param name="first"></param>
/// <param name="second"></param>
/// <returns>true if successfully added, false if either element are already in the dictionary</returns>
public Boolean TryAdd(TFirst first, TSecond second)
{
if (firstToSecond.ContainsKey(first) || secondToFirst.ContainsKey(second))
return false;
firstToSecond.Add(first, second);
secondToFirst.Add(second, first);
return true;
}
/// <summary>
/// Find the TSecond corresponding to the TFirst first.
/// Returns false if first is not in the dictionary.
/// </summary>
/// <param name="first">the key to search for</param>
/// <param name="second">the corresponding value</param>
/// <returns>true if first is in the dictionary, false otherwise</returns>
public Boolean TryGetByFirst(TFirst first, out TSecond second)
{
return firstToSecond.TryGetValue(first, out second);
}
/// <summary>
/// Find the TFirst corresponding to the TSecond second.
/// Returns false if second is not in the dictionary.
/// </summary>
/// <param name="second">the key to search for</param>
/// <param name="first">the corresponding value</param>
/// <returns>true if second is in the dictionary, false otherwise</returns>
public Boolean TryGetBySecond(TSecond second, out TFirst first)
{
return secondToFirst.TryGetValue(second, out first);
}
/// <summary>
/// Remove the record containing first, if there is one.
/// </summary>
/// <param name="first"></param>
/// <returns> If first is not in the dictionary, returns false, otherwise true</returns>
public Boolean TryRemoveByFirst(TFirst first)
{
TSecond second;
if (!firstToSecond.TryGetValue(first, out second))
return false;
firstToSecond.Remove(first);
secondToFirst.Remove(second);
return true;
}
/// <summary>
/// Remove the record containing second, if there is one.
/// </summary>
/// <param name="second"></param>
/// <returns> If second is not in the dictionary, returns false, otherwise true</returns>
public Boolean TryRemoveBySecond(TSecond second)
{
TFirst first;
if (!secondToFirst.TryGetValue(second, out first))
return false;
secondToFirst.Remove(second);
firstToSecond.Remove(first);
return true;
}
#endregion
/// <summary>
/// The number of pairs stored in the dictionary
/// </summary>
public Int32 Count
{
get { return firstToSecond.Count; }
}
/// <summary>
/// Removes all items from the dictionary.
/// </summary>
public void Clear()
{
firstToSecond.Clear();
secondToFirst.Clear();
}
}
