SYSK 110: Two-Key Dictionary Class
The other day I needed to have a dictionary (i.e. fast search by key) class that works on two keys. This is somewhat akin to a three level tree structure -- first level has elements specified by first key, second level – by second key, and the final third level are the actual data nodes.
Below is the code that does just that (disclaimer – this was created in about 15 min… no real testing, yet… use at your own risk!)
[Serializable]
public class NestedDictionary<TKey, TKey2, TValue> : Dictionary<TKey, Dictionary<TKey2, TValue>>
{
public void Add(TKey key1, TKey2 key2, TValue value)
{
if (base.ContainsKey(key1) == false)
base.Add(key1, new Dictionary<TKey2, TValue>());
base[key1].Add(key2, value);
}
public TValue this[TKey key1, TKey2 key2]
{
get
{
TValue result = default(TValue);
if (base.ContainsKey(key1) == true)
{
if (base[key1].ContainsKey(key2) == true)
result = base[key1][key2];
}
return result;
}
set
{
if (base.ContainsKey(key1) == false)
base.Add(key1, new Dictionary<TKey2, TValue>());
if (base[key1].ContainsKey(key2) == false)
base[key1][key2] = value;
else
base[key1].Add(key2, value);
}
}
public virtual bool Remove(TKey key1, TKey2 key2)
{
bool result = false;
if (base.ContainsKey(key1) == true)
{
if (base[key1].ContainsKey(key2) == true)
result = base[key1].Remove(key2);
}
return result;
}
public TKey[] FirstLevelKeys()
{
List<TKey> result = new List<TKey>();
result.AddRange(base.Keys);
return result.ToArray();
}
public TKey2[] SecondLevelKeys(TKey key1)
{
List<TKey2> result = new List<TKey2>();
if (base.ContainsKey(key1) == true)
result.AddRange(base[key1].Keys);
return result.ToArray();
}
}