private static V TryGetStacked(KVStack item, K key, V defaultValue)
{
for (var i = item; i != KVStack.End; i = i.Tail)
{
if (Equals(i.Key, key))
{
return(i.Value);
}
}
return(defaultValue);
}
private static KVStack Update(KVStack item, KVStack newItem)
{
if (Equals(item.Key, newItem.Key))
{
return(item.Tail.Push(newItem));
}
for (KVStack i = item.Tail, tested = KVStack.End; i != KVStack.End; i = i.Tail, tested = tested.Push(i))
{
if (Equals(i.Key, newItem.Key))
{
var result = i.Tail.Push(newItem);
for (var ti = tested; ti != KVStack.End; ti = ti.Tail)
{
result = result.Push(ti);
}
return(result);
}
}
return(item.Push(newItem));
}
public KVStack Push(KVStack head)
{
return(new KVStack(head.Key, head.Value, this));
}
public KVStack(K key, V value, KVStack tail = null)
{
Key = key;
Value = value;
Tail = tail ?? End;
}
