From a008409bcee1cc93dff4ab1e640ed4e229428538 Mon Sep 17 00:00:00 2001
From: Harald Wolff <haraldwolff@skyoffice>
Date: Mon, 24 Feb 2020 17:25:51 +0100
Subject: [PATCH] Upgrade BTree<>

---
 btree/BTree.cs | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/btree/BTree.cs b/btree/BTree.cs
index 7c0ad60..619b2e5 100644
--- a/btree/BTree.cs
+++ b/btree/BTree.cs
@@ -1,10 +1,12 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
+using ln.types.collections;
 
 namespace ln.types.btree
 {
-    public class BTree<K,V>
+    public class BTree<K,V> : IDict<K,V>
     {
         public Comparison<K> Comparison { get; }
         public int Count => count;
@@ -229,6 +231,34 @@ namespace ln.types.btree
             }
             return null;
         }
+        private TreeNode FindFirstGE(K key)
+        {
+            TreeNode node = headNode;
+            TreeNode minNode = null;
+
+            while (node != null)
+            {
+                if ((Comparison(node.Key, key) >= 0) && ((minNode == null) || (Comparison(node.Key, minNode.Key) < 0)))
+                    minNode = node;
+
+                int comp = Comparison(key, node.Key);
+                if (comp == 0)
+                    return node;
+                else if (comp < 0)
+                {
+                    if (node.Left == null)
+                        return minNode;
+                    node = node.Left;
+                }
+                else
+                {
+                    if (node.Right == null)
+                        return minNode;
+                    node = node.Right;
+                }
+            }
+            return null;
+        }
 
         private TreeNode Previous(TreeNode node)
         {
@@ -409,6 +439,21 @@ namespace ln.types.btree
             }
         }
 
+        public IEnumerable<K> KeysGreaterEqual(K first)
+        {
+            TreeNode node = FindFirstGE(first);
+            while (node != null)
+            {
+                yield return node.Key;
+                node = Next(node);
+            }
+        }
+
+        public void Add(object key, object value) => Add((K)key, (V)value);
+        public void Remove(object key) => Remove((K)key);
+        public bool ContainsKey(object key) => ContainsKey((K)key);
+        public object this[object key] { get => this[(K)key]; set => this[(K)key] = (V)value; }
+
         public IEnumerable<K> Keys
         {
             get
@@ -434,6 +479,9 @@ namespace ln.types.btree
             }
         }
 
+        IEnumerable IDict.Keys => Keys;
+        IEnumerable IDict.Values => Values;
+
         class TreeNode
         {
             public BTree<K, V> Tree { get; }