/// <summary>
/// Tries to get the Value associated with a given Key
/// </summary>
/// <param name="key">Key</param>
/// <param name="value">Value, will be null if the key does not exist or has no value associated with it</param>
/// <returns>True if the Key exists in the Trie and has a value associated with it, False if it does not</returns>
public bool TryGetValue(TKey key, out TValue value)
{
value = null;
ITrieNode <TKeyBit, TValue> node = this._root;
IEnumerable <TKeyBit> bs = this._keyMapper(key);
foreach (TKeyBit b in bs)
{
//Bail out early if key does not exist
if (!node.TryGetChild(b, out node))
{
return(false);
}
}
if (node.HasValue)
{
value = node.Value;
return(true);
}
else
{
return(false);
}
}
/// <summary>
/// Finds and returns a Node that has the shortest prefix match greater than or equal to the given Key using the given Key to Key Bit mapping function
/// </summary>
/// <param name="bs">Key Bits</param>
/// <returns>Null if the Key does not map to a Node</returns>
/// <remarks>
/// The ability to provide a specific sequence of key bits may be useful for custom lookups where you don't necessarily have a value of the <strong>TKey</strong> type but do have values of the <strong>TKeyBit</strong> type
/// </remarks>
public ITrieNode <TKeyBit, TValue> FindSuccessor(IEnumerable <TKeyBit> bs)
{
ITrieNode <TKeyBit, TValue> node = this._root;
foreach (TKeyBit b in bs)
{
//Bail out early if key does not exist
if (!node.TryGetChild(b, out node))
{
return(null);
}
}
Queue <ITrieNode <TKeyBit, TValue> > depthFirstQueue = new Queue <ITrieNode <TKeyBit, TValue> >();
depthFirstQueue.Enqueue(node);
while (depthFirstQueue.Count > 0)
{
node = depthFirstQueue.Dequeue();
if (node.HasValue)
{
return(node);
}
foreach (var child in node.Children.OrderBy(n => n.KeyBit, this.KeyBitComparer))
{
depthFirstQueue.Enqueue(child);
}
}
return(null);
}
/// <summary>
/// Finds and returns a Node for the given sequence of Key Bits
/// </summary>
/// <param name="bs">Key Bits</param>
/// <returns>Null if the Key does not map to a Node</returns>
/// <remarks>
/// The ability to provide a specific sequence of key bits may be useful for custom lookups where you don't necessarily have a value of the <strong>TKey</strong> type but do have values of the <strong>TKeyBit</strong> type
/// </remarks>
public ITrieNode <TKeyBit, TValue> Find(IEnumerable <TKeyBit> bs)
{
ITrieNode <TKeyBit, TValue> node = this._root;
foreach (TKeyBit b in bs)
{
//Bail out early if key does not exist
if (!node.TryGetChild(b, out node))
{
return(null);
}
}
return(node);
}
/// <summary>
/// Finds and returns a Node that has the longest prefix match for the given Key using the given Key to Key Bit mapping function
/// </summary>
/// <param name="bs">Key bits</param>
/// <returns>Null if the Key does not map to a Node</returns>
/// <remarks>
/// The ability to provide a specific sequence of key bits may be useful for custom lookups where you don't necessarily have a value of the <strong>TKey</strong> type but do have values of the <strong>TKeyBit</strong> type
/// </remarks>
public ITrieNode <TKeyBit, TValue> FindPredecessor(IEnumerable <TKeyBit> bs)
{
ITrieNode <TKeyBit, TValue> node = this._root;
ITrieNode <TKeyBit, TValue> predecessor = null;
foreach (TKeyBit b in bs)
{
//Bail out early if key does not exist
if (!node.TryGetChild(b, out node))
{
return(predecessor);
}
if (node.HasValue)
{
predecessor = node;
}
}
return(predecessor);
}
/// <summary>
/// Remove the value that a key leads to and any redundant nodes which result from this action
/// </summary>
/// <param name="key">Key of the value to remove</param>
public void Remove(TKey key)
{
ITrieNode <TKeyBit, TValue> node = this._root;
IEnumerable <TKeyBit> bs = this._keyMapper(key);
foreach (TKeyBit b in bs)
{
//Bail out early if the key doesn't go anywhere
if (!node.TryGetChild(b, out node))
{
return;
}
}
node.Value = null;
//Remove all ancestor nodes which don't lead to a value.
while (!node.IsRoot && !node.HasValue && node.Count == 0)
{
TKeyBit prevKey = node.KeyBit;
node = node.Parent;
node.RemoveChild(prevKey);
}
}
