Final push

Author: LoneWandererProductions

CommonExtendedObjectsTests/SortedKvStoreTests.cs

@@ -6,12 +6,9 @@
  * PROGRAMMER:  Peter Geinitz (Wayfarer)
  */
 
-using System;
 using System.Buffers;
-using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
-using System.Windows.Documents;
 using ExtendedSystemObjects;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
@@ -209,7 +206,7 @@ public void PerformanceRemoveCompact()
         /// Inserts the key1 into empty store should keep arrays in synchronize.
         /// </summary>
         [TestMethod]
-        public void InsertKey1IntoEmptyStoreShouldKeepArraysInSync()
+        public void InsertKeyIntoEmptyStoreShouldKeepArraysInSync()
         {
             // Arrange
             var store = new SortedKvStore();
@@ -494,7 +491,32 @@ public void BinarySearch()
             Trace.WriteLine(store.ToString());
             var position = store.BinarySearch(9);
 
-            Assert.AreEqual(9, position, "Wrong position.");
+            Assert.AreEqual(-10, position, "Wrong position.");
+        }
+
+        /// <summary>
+        /// Binaries the search fails due to unsorted placeholder values.
+        /// </summary>
+        [TestMethod]
+        public void BinarySearchFailsDueToUnsortedPlaceholderValues()
+        {
+            var store = new SortedKvStore(128);
+
+            // Add 10 sorted keys: 1 through 10
+            for (int i = 1; i <= 10; i++)
+            {
+                store.Add(i, i);
+            }
+
+            Trace.WriteLine(store.ToString());
+
+            // We now search for 10, which is present
+            var result = store.BinarySearch(10);
+
+            Trace.WriteLine($"BinarySearch(10) returned: {result}");
+
+            // Expected index is 9 (0-based index of key = 10)
+            Assert.AreEqual(9, result, "BinarySearch returned incorrect index due to unsorted placeholder values beyond the valid count.");
         }
     }
 }

CommonExtendedObjectsTests/Utilities.cs

@@ -361,5 +361,27 @@ public void CompareCustomVsArrayBinarySearchPerformance()
             Assert.IsTrue(swCustom.ElapsedMilliseconds < swArray.ElapsedMilliseconds * 3,
                 $"Custom BinarySearch is too slow: {swCustom.ElapsedMilliseconds} ms vs {swArray.ElapsedMilliseconds} ms");
         }
+
+        /// <summary>
+        /// Binaries the search bug.
+        /// </summary>
+        [TestMethod]
+        public void BinarySearchBug()
+        {
+            var sortedKeys = new int[128];
+
+            for (var i = 0; i < 10; i++)
+            {
+                sortedKeys[i] = i+1;
+            }
+            for (var i = 10; i < 128; i++)
+            {
+                sortedKeys[i] = 0; ;
+            }
+
+            var idx = Utility.BinarySearch(sortedKeys, 14, 10);
+
+            Assert.AreEqual(-15, idx ,"Found the bug.");
+        }
     }
 }

ExtendedSystemObjects/SortedKvStore.cs

@@ -394,7 +394,56 @@ public void Compact()
         /// </returns>
         public int BinarySearch(int key)
         {
-            return Utility.BinarySearch(_keys.AsSpan(), Count, key);
+            int left = 0, right = Count - 1;
+            var keysSpan = _keys.AsSpan()[..Count];
+            var occupiedSpan = _occupied.AsSpan()[..Count];
+
+            while (left <= right)
+            {
+                int mid = left + ((right - left) >> 1);
+                int midKey = keysSpan[mid];
+
+                if (midKey == key)
+                {
+                    if (occupiedSpan[mid] != 0)
+                        return mid; // found active key
+
+                    // Found deleted slot, try to probe neighbors near mid for active key with same key
+                    // Usually deletions are rare, so probing few neighbors is cheap
+
+                    // probe left neighbors
+                    for (int i = mid - 1; i >= left && keysSpan[i] == key; i--)
+                    {
+                        if (occupiedSpan[i] != 0)
+                            return i;
+                    }
+                    // probe right neighbors
+                    for (int i = mid + 1; i <= right && keysSpan[i] == key; i++)
+                    {
+                        if (occupiedSpan[i] != 0)
+                            return i;
+                    }
+
+                    // no active key found
+                    return ~left;
+                }
+
+                if (midKey < key)
+                {
+                    left = mid + 1;
+                }
+                else
+                {
+                    right = mid - 1;
+                }
+            }
+
+            // Key not found; try to move left forward to next occupied slot for insertion index
+            int insertionIndex = left;
+            while (insertionIndex < Count && occupiedSpan[insertionIndex] == 0)
+                insertionIndex++;
+
+            return ~insertionIndex;
         }
 
         /// <summary>

InterpreteTests/CommandBuilder.cs

@@ -9,7 +9,6 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using ExtendedSystemObjects;
-using Interpreter;
 using Interpreter.ScriptEngine;
 using Microsoft.VisualStudio.TestTools.UnitTesting;