From a3af8ae223cb1be67e8549f0c08a38c74c105d4d Mon Sep 17 00:00:00 2001
From: Griff0ly0n <mithunmk93@gmail.com>
Date: Sat, 31 Mar 2018 16:30:34 +0530
Subject: [PATCH] Prevent duplication of cells while filtering

---
 addon/components/ember-collection.js | 48 ++++++++--------------------
 1 file changed, 13 insertions(+), 35 deletions(-)

diff --git a/addon/components/ember-collection.js b/addon/components/ember-collection.js
index 1f859208..eb24b623 100644
--- a/addon/components/ember-collection.js
+++ b/addon/components/ember-collection.js
@@ -36,7 +36,6 @@ export default Component.extend({
     // this.cellCount = undefined;
     this.contentElement = undefined;
     this._cells = A();
-    this._cellMap = Object.create(null);
 
     // TODO: Super calls should always be at the top of the constructor.
     // I had to move the super call after the properties were defined to
@@ -141,9 +140,6 @@ export default Component.extend({
       this._cellLayout.length = numItems;
     }
 
-    var priorMap = this._cellMap;
-    var cellMap = Object.create(null);
-
     var index = this._cellLayout.indexAt(this._scrollLeft, this._scrollTop, this._clientWidth, this._clientHeight);
     var count = this._cellLayout.count(this._scrollLeft, this._scrollTop, this._clientWidth, this._clientHeight);
     var items = this._items;
@@ -157,40 +153,24 @@ export default Component.extend({
 
     for (i=0; i<count; i++) {
       itemIndex = index+i;
-      itemKey = identity(items.objectAt(itemIndex));
-      if (priorMap) {
-        cell = priorMap[itemKey];
-      }
-      if (cell) {
+      newItems.push(itemIndex);
+    }
+
+    for (i=0; i<this._cells.length; i++) {
+      cell = this._cells[i];
+      if (newItems.length) {
+        itemIndex = newItems.pop();
+        let item = items.objectAt(itemIndex);
+        itemKey = identity(item);
         style = this._cellLayout.formatItemStyle(itemIndex, this._clientWidth, this._clientHeight);
         set(cell, 'style', style);
-        set(cell, 'hidden', false);
         set(cell, 'key', itemKey);
         set(cell, 'index', itemIndex);
-        cellMap[itemKey] = cell;
+        set(cell, 'item', item);
+        set(cell, 'hidden', false);
       } else {
-        newItems.push(itemIndex);
-      }
-    }
-
-    for (i=0; i<this._cells.length; i++) {
-      cell = this._cells[i];
-      if (!cellMap[cell.key]) {
-        if (newItems.length) {
-          itemIndex = newItems.pop();
-          let item = items.objectAt(itemIndex);
-          itemKey = identity(item);
-          style = this._cellLayout.formatItemStyle(itemIndex, this._clientWidth, this._clientHeight);
-          set(cell, 'style', style);
-          set(cell, 'key', itemKey);
-          set(cell, 'index', itemIndex);
-          set(cell, 'item', item);
-          set(cell, 'hidden', false);
-          cellMap[itemKey] = cell;
-        } else {
-          set(cell, 'hidden', true);
-          set(cell, 'style', 'height: 0; display: none;');
-        }
+        set(cell, 'hidden', true);
+        set(cell, 'style', 'height: 0; display: none;');
       }
     }
 
@@ -200,10 +180,8 @@ export default Component.extend({
       itemKey = identity(item);
       style = this._cellLayout.formatItemStyle(itemIndex, this._clientWidth, this._clientHeight);
       cell = new Cell(itemKey, item, itemIndex, style);
-      cellMap[itemKey] = cell;
       this._cells.pushObject(cell);
     }
-    this._cellMap = cellMap;
   },
 
   _isGlimmer2() {