Added overloaded constructor that takes an AddDuplicateBehavior enum to specify how the tree should behave when you try to add a node with a duplicate coordinate

Author: codeandcats

KdTreeLib/KdTree.cs

@@ -5,11 +5,24 @@
 using System.Linq;
 using System.Runtime.Serialization.Formatters.Binary;
 using System.Text;
-using System.Threading.Tasks;
-using KdTree.Math;
 
 namespace KdTree
 {
+	public enum AddDuplicateBehavior
+	{
+		Skip,
+		Error,
+		Update
+	}
+
+	public class DuplicateNodeError : Exception
+	{
+		public DuplicateNodeError()
+			: base("Cannot Add Node With Duplicate Coordinates")
+		{
+		}
+	}
+
 	[Serializable]
 	public class KdTree<TKey, TValue> : IKdTree<TKey, TValue>
 	{
@@ -20,12 +33,20 @@ public KdTree(int dimensions, ITypeMath<TKey> typeMath)
 			Count = 0;
 		}
 
+		public KdTree(int dimensions, ITypeMath<TKey> typeMath, AddDuplicateBehavior addDuplicateBehavior)
+			: this(dimensions, typeMath)
+		{
+			AddDuplicateBehavior = addDuplicateBehavior;
+		}
+
 		private int dimensions;
 
 		private ITypeMath<TKey> typeMath = null;
 
 		private KdTreeNode<TKey, TValue> root = null;
 
+		public AddDuplicateBehavior AddDuplicateBehavior { get; private set; }
+
 		public bool Add(TKey[] point, TValue value)
 		{
 			var nodeToAdd = new KdTreeNode<TKey, TValue>(point, value);
@@ -46,7 +67,24 @@ public bool Add(TKey[] point, TValue value)
 
 					// Does the node we're adding have the same hyperpoint as this node?
 					if (typeMath.AreEqual(point, parent.Point))
-						return false;
+					{
+						switch (AddDuplicateBehavior)
+						{
+							case AddDuplicateBehavior.Skip:
+								return false;
+								
+							case AddDuplicateBehavior.Error:
+								throw new DuplicateNodeError();
+
+							case AddDuplicateBehavior.Update:
+								parent.Value = value;
+								break;
+
+							default:
+								// Should never happen
+								throw new Exception("Unexpected AddDuplicateBehavior");
+						}
+					}
 
 					// Which side does this node sit under in relation to it's parent at this level?
 					int compare = typeMath.Compare(point[dimension], parent.Point[dimension]);

KdTreeTestsLib/KdTreeTests.cs

@@ -64,6 +64,66 @@ public void TestAdd()
 			Assert.AreEqual(testNodes.Count, tree.Count);
 		}
 
+		[TestMethod]
+		[TestCategory("KdTree")]
+		public void TestAddDuplicateInSkipMode()
+		{
+			tree = new KdTree<float, string>(2, new FloatMath());
+
+			Assert.AreEqual(AddDuplicateBehavior.Skip, tree.AddDuplicateBehavior);
+
+			AddTestNodes();
+
+			var count = tree.Count;
+
+			var added = tree.Add(testNodes[0].Point, "Some other value");
+
+			Assert.AreEqual(false, added);
+			Assert.AreEqual(count, tree.Count);
+		}
+
+		[TestMethod]
+		[TestCategory("KdTree")]
+		public void TestAddDuplicateInErrorMode()
+		{
+			tree = new KdTree<float, string>(2, new FloatMath(), AddDuplicateBehavior.Error);
+
+			AddTestNodes();
+
+			var count = tree.Count;
+			Exception error = null;
+
+			try
+			{
+				tree.Add(testNodes[0].Point, "Some other value");
+			}
+			catch (Exception e)
+			{
+				error = e;
+			}
+
+			Assert.AreEqual(count, tree.Count);
+			Assert.IsNotNull(error);
+			Assert.IsInstanceOfType(error, typeof(DuplicateNodeError));
+		}
+
+		[TestMethod]
+		[TestCategory("KdTree")]
+		public void TestAddDuplicateInUpdateMode()
+		{
+			tree = new KdTree<float, string>(2, new FloatMath(), AddDuplicateBehavior.Update);
+
+			AddTestNodes();
+
+			var newValue = "I love chicken, I love liver, Meow Mix Meow Mix please deliver";
+
+			tree.Add(testNodes[0].Point, newValue);
+
+			var actualValue = tree.FindValueAt(testNodes[0].Point);
+
+			Assert.AreEqual(newValue, actualValue);
+		}
+
 		[TestMethod]
 		[TestCategory("KdTree")]
 		public void TestTryFindValueAt()