speedups maybe

changed Set function and Find(routing)Index) to specialize on class (no
virtual dispatch) or using generics.

PersistentOrderedMap/BTreeFunctions.cs

@@ -1,4 +1,3 @@
-using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
@@ -42,27 +41,28 @@ namespace PersistentOrderedMap
             }
         }
 
-        public static Node<K> Set<K, V>(Node<K> root, K key, V value, IKeyStrategy<K> strategy, OwnerId owner, out bool countChanged)
+        public static Node<K> Set<K, V, TStrategy>(Node<K> root, K key, V value, TStrategy strategy, OwnerId owner, out bool countChanged)
+            where TStrategy : IKeyStrategy<K>
         {
             root = root.EnsureEditable(owner);
 
             // Todo, this should really be made a tuple return value to not stress the GC
-            var splitResult = InsertRecursive(root, key, value, strategy, owner, out countChanged);
+            var (newNode, sep) = InsertRecursive(root, key, value, strategy, owner, out countChanged);
 
-            if (splitResult != null)
+            if (newNode != null)
             {
                 var newRoot = strategy.UsesPrefixes 
                     ? new PrefixInternalNode<K>(owner) 
                     : new InternalNode<K>(owner);
                 
-                newRoot.Keys[0] = splitResult.Separator;
+                newRoot.Keys[0] = sep;
                 newRoot.Children[0] = root;
-                newRoot.Children[1] = splitResult.NewNode;
+                newRoot.Children[1] = newNode;
                 newRoot.SetCount(1);
                 
                 if (strategy.UsesPrefixes)
                 {
-                    newRoot.AllPrefixes[0] = strategy.GetPrefix(splitResult.Separator);
+                    newRoot.AllPrefixes[0] = strategy.GetPrefix(sep);
                 }
 
                 return newRoot;
@@ -71,7 +71,7 @@ namespace PersistentOrderedMap
             return root;
         }
 
-        private static SplitResult<K>? InsertRecursive<K, V>(Node<K> node, K key, V value, IKeyStrategy<K> strategy, OwnerId owner, out bool added)
+        private static (Node<K>? newNode, K separator ) InsertRecursive<K, V>(Node<K> node, K key, V value, IKeyStrategy<K> strategy, OwnerId owner, out bool added)
         {
             long keyPrefix = strategy.UsesPrefixes ? strategy.GetPrefix(key) : 0;
 
@@ -84,14 +84,14 @@ namespace PersistentOrderedMap
                 {
                     leaf.Values[index] = value;
                     added = false;
-                    return null;
+                    return (null, default);
                 }
 
                 added = true;
                 if (leaf.Header.Count < LeafNode<K, V>.Capacity)
                 {
                     InsertIntoLeaf(leaf, index, key, value, strategy);
-                    return null;
+                    return (null, default);
                 }
                 else
                 {
@@ -106,21 +106,21 @@ namespace PersistentOrderedMap
                 var child = internalNode.Children[index]!.EnsureEditable(owner);
                 internalNode.Children[index] = child;
 
-                var split = InsertRecursive(child, key, value, strategy, owner, out added);
+                var (newNode, sep) = InsertRecursive(child, key, value, strategy, owner, out added);
 
-                if (split != null)
+                if (newNode != null)
                 {
                     if (internalNode.Header.Count < InternalNode<K>.Capacity - 1)
                     {
-                        InsertIntoInternal(internalNode, index, split.Separator, split.NewNode, strategy);
+                        InsertIntoInternal(internalNode, index, sep, newNode, strategy);
-                        return null;
+                        return (null, default);
                     }
                     else
                     {
-                        return SplitInternal(internalNode, index, split.Separator, split.NewNode, strategy, owner);
+                        return SplitInternal(internalNode, index, sep, newNode, strategy, owner);
                     }
                 }
-                return null;
+                return (null, default);
             }
         }
 
@@ -189,7 +189,7 @@ namespace PersistentOrderedMap
         // ---------------------------------------------------------
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal static int FindIndex<K, TStrategy>(Node<K> node, K key, long keyPrefix, TStrategy strategy)
+        internal static int FindIndex<K,V, TStrategy>(LeafNode<K,V> node, K key, long keyPrefix, TStrategy strategy)
             where TStrategy : IKeyStrategy<K>
         {
             if (typeof(K) == typeof(int))

PersistentOrderedMap/Iterator.cs

@@ -31,6 +31,9 @@ where TStrategy : IKeyStrategy<K>
 
 // Fixed-size buffer for the path. 
 // Depth 16 * 32 (branching factor) = Exabytes of capacity.
+// The B tree is, theoretically, not limited by the size of an int, like
+// all int-indexed data structures (or bit partitioned ones).
+// This should be enough for anyone.
 [InlineArray(16)]
 internal struct IterNodeBuffer<K>
 {
@@ -138,7 +141,7 @@ public struct BTreeEnumerator<K, V, TStrategy> : IEnumerator<KeyValuePair<K, V>>
 
             // Find index in Leaf
             _currentLeaf = node.AsLeaf<V>();
-            int index = BTreeFunctions.FindIndex<K, TStrategy>(_currentLeaf, key, keyPrefix, _strategy);
+            int index = BTreeFunctions.FindIndex<K,V, TStrategy>(_currentLeaf, key, keyPrefix, _strategy);
             
             // Set position to (index - 1) so that the first MoveNext() lands on 'index'
             _currentLeafIndex = index - 1;