public bool TryGetValue(K key, out V value)
{
KvpNode <K, V> current = root;
while (!current.IsNil)
{
int comparison = _comparer.Compare(key, current.Payload.Key);
if (comparison < 0)
{
current = current.Left;
}
else if (comparison > 0)
{
current = current.Right;
}
else
{
value = current.Payload.Value;
return(true);
}
}
value = default;
return(false);
}
public Descent Descend()
{
if (_current.IsNil)
{
return(_policy == NodeLocationPolicy.NoInsert ? Descent.NotFound : Descent.Found);
}
else
{
int comparison = _comparer.Compare(_targetKey, _current.Payload.Key);
if (comparison < 0)
{
_current = _current.Left;
return(Descent.Left);
}
else if (comparison > 0)
{
_current = _current.Right;
return(Descent.Right);
}
else
{
return(_policy == NodeLocationPolicy.NoUpdate ? Descent.NotFound : Descent.Found);
}
}
}
public NodeLocator(
K targetKey, IComparer <K> comparer, NodeLocationPolicy policy, KvpNode <K, V> root)
{
_targetKey = targetKey;
_comparer = comparer;
_policy = policy;
_current = root;
}
public IPerststentMap <K, V> Put(K key, V value, out Maybe <V> oldValue)
{
KeyValuePair <K, V> kvp = new KeyValuePair <K, V>(key, value);
NodeLocator locator = new NodeLocator(key, _comparer, NodeLocationPolicy.Default, root);
KvpNode <K, V> newRoot = DoInsertOrUpdate(kvp, _ => kvp, locator);
if (locator.CurrentNode.IsNil) // insertion
{
oldValue = Maybe <V> .Nothing;
return(new PersistentMap <K, V>(newRoot, Count + 1, _comparer));
}
else // update
{
oldValue = new Maybe <V>(locator.CurrentNode.Payload.Value);
return(new PersistentMap <K, V>(newRoot, Count, _comparer));
}
}
public bool ContainsKey(K key)
{
KvpNode <K, V> current = root;
while (!current.IsNil)
{
int comparison = _comparer.Compare(key, current.Payload.Key);
if (comparison < 0)
{
current = current.Left;
}
else if (comparison > 0)
{
current = current.Right;
}
else
{
return(true);
}
}
return(false);
}
private PersistentMap(KvpNode <K, V> root, int count, IComparer <K> comparer) : base(root)
{
Count = count;
_comparer = comparer;
}
public IPerststentMap <K, V> PutIfAbsent(K key, V value)
{
KeyValuePair <K, V> kvp = new KeyValuePair <K, V>(key, value);
NodeLocator locator = new NodeLocator(key, _comparer, NodeLocationPolicy.NoUpdate, root);
// the update calculation is not executed
KvpNode <K, V> newRoot = DoInsertOrUpdate(kvp, _ => default, locator);
public KvpNode(KeyValuePair <K, V> kvp, KvpNode <K, V> left, KvpNode <K, V> right)
: base(left, right)
{
Payload = kvp;
}