WIP on spatial indexes

lib/src/org/mimirdb/pip/lib/KDTree.scala

@@ -0,0 +1,77 @@
+package org.mimirdb.pip.lib
+
+class KDTree[I: Ordered, V](dimensions: Int)
+{
+  type Key = Array[I]
+  var root: Option[Node] = None
+
+  def insert(position: Key, value: V): Unit =
+  {
+    assert(position.size == dimensions)
+    root = root match {
+      case Some(node) => node.insert(position, value)
+      case None => Leaf(position, value, 0)
+    }
+  }
+
+
+  sealed trait Node
+  {
+    def insert(position: Key, value: V): Node
+  }
+
+  class Inner(
+    split: I, 
+    idx: Int,
+    var left: Option[Node] = None,
+    var right: Option[Node] = None
+  )
+  {
+
+    def insert(position: Key, value: V): Node = 
+    {
+      if(position(idx).compare(split) >= 0){
+        // position(idx) >= split
+        if(right.isEmpty){
+          right = Some(Leaf(position, value, idx+1 % dimensions))
+        } else {
+          right = Some(right.get.insert(position, value))
+        }
+      } else {
+        // position(idx) < split
+        if(left.isEmpty){
+          left = Some(Leaf(position, value, idx+1 % dimensions))
+        } else {
+          left = Some(left.get.insert(position, value))
+        }
+
+      }
+      return this
+    }
+  }
+
+
+  class Leaf(position: Key, value: V, idx: Int)
+  {
+    def insert(otherPosition: Key, otherValue: V): Node =
+    {
+      if(position(idx).compare(otherPosition(idx)) >= 0){
+        Inner(
+          split = position(idx), 
+          idx = idx,
+          left = Some(Leaf(otherPosition, otherValue, idx+1 % dimensions)),
+          right = Some(copy(idx = idx+1 % dimensions)),
+        )
+      } else {
+        Inner(
+          split = otherPosition(idx), 
+          idx = idx,
+          left = Some(copy(idx = idx+1 % dimensions)),
+          right = Some(Leaf(otherPosition, otherValue, idx+1 % dimensions)),
+        )
+      }
+    }
+  }
+
+
+}