Fix kdtree implementation.

vendor/kdtree/heap.js

@@ -0,0 +1,112 @@
+/**
+ * kdtree
+ *
+ * Is a modified and google closure adapted kdtree implementation
+ * of https://github.com/ubilabs/kd-tree-javascript.
+ *
+ * @author Andrey Antukh <niwi@niwi.nz>, 2016
+ * @license MIT License <https://opensource.org/licenses/MIT>
+ */
+
+goog.provide("kdtree.heap");
+goog.provide("kdtree.heap.MinHeap");
+
+goog.scope(function() {
+  "use strict";
+
+  const compare = (x,y) => x-y;
+
+  class MinHeap {
+    constructor(cmp) {
+      this.cmp = cmp || compare;
+      this.heap = [];
+      this.size = 0;
+    }
+
+    insert(item) {
+      const heap  = this.heap;
+
+      let index = this.size++;
+      let parent = (index-1)>>1;
+
+      heap[index] = item;
+
+      while ((index > 0) && this.cmp(heap[parent], item) > 0) {
+        const tmp = heap[parent];
+        heap[parent] = heap[index];
+        heap[index] = tmp;
+        index = parent;
+        parent = (index-1)>>1;
+      }
+    }
+
+    isEmpty() {
+      return this.size === 0;
+    }
+
+    peek() {
+      return this.heap[0];
+    }
+
+    removeHead() {
+      const heap = this.heap;
+      const cmp = this.cmp;
+
+      if (this.size === 0) {
+        return null;
+      }
+
+      const head = heap[0];
+
+      this._bubble(0);
+      return head;
+    }
+
+    remove(item) {
+      const heap = this.heap;
+
+      for (let i = 0; i < this.size; ++i) {
+        if (heap[i] === item) {
+          this._bubble(i);
+          return true;
+        }
+      }
+
+      return false;
+    }
+
+    _bubble(index) {
+      const heap = this.heap;
+      const cmp = this.cmp;
+
+      heap[index] = heap[--this.size];
+      heap[this.size] = null;
+
+      while (true) {
+
+      const leftIndex = (index<<1)+1;
+        const rightIndex = (index<<1)+2;
+        let minIndex = index;
+
+        if (leftIndex < this.size && cmp(heap[leftIndex], heap[minIndex]) < 0) {
+          minIndex = leftIndex;
+        }
+
+        if (rightIndex < this.size && cmp(heap[rightIndex], heap[minIndex]) < 0) {
+          minIndex = rightIndex;
+        }
+
+        if (minIndex !== index) {
+          const tmp = heap[index];
+          heap[index] = heap[minIndex];
+          heap[minIndex] = tmp;
+          index = minIndex;
+        } else {
+          break;
+        }
+      }
+    }
+  }
+
+  kdtree.heap.MinHeap = MinHeap;
+});