From 00e7e3141819e14ced3279fa5dfb8eba4ff89e5f Mon Sep 17 00:00:00 2001
From: Igor Minar <igor@angularjs.org>
Date: Mon, 26 Nov 2012 20:25:38 +0100
Subject: [PATCH] fix(ngRepeat): attempt to simplify and improve existing fix
 for #933

I'm keeping this in for future reference. The issue with this solution
is that if we shift() the first item in the array, the whole repeater
DOM will be rebuilt from scratch, we need to do better than that.
---
 src/apis.js                  |  4 ++--
 src/ng/directive/ngRepeat.js | 34 +++++++++-------------------------
 2 files changed, 11 insertions(+), 27 deletions(-)

diff --git a/src/apis.js b/src/apis.js
index 098d9cdd6be8..0e94e2a55ce2 100644
--- a/src/apis.js
+++ b/src/apis.js
@@ -98,12 +98,12 @@ HashQueueMap.prototype = {
       }
     }
   },
-  
+
   /**
    * return the first item without deleting it
    */
   peek: function(key) {
-    var array = this[key = hashKey(key)];
+    var array = this[hashKey(key)];
     if (array) {
     return array[0];
     }
diff --git a/src/ng/directive/ngRepeat.js b/src/ng/directive/ngRepeat.js
index 021845fae0ad..8c934b767210 100644
--- a/src/ng/directive/ngRepeat.js
+++ b/src/ng/directive/ngRepeat.js
@@ -88,7 +88,7 @@ var ngRepeatDirective = ngDirective({
       // We need an array of these objects since the same object can be returned from the iterator.
       // We expect this to be a rare case.
       var lastOrder = new HashQueueMap();
-      var indexValues = [];
+
       scope.$watch(function ngRepeatWatch(scope){
         var index, length,
             collection = scope.$eval(rhs),
@@ -119,18 +119,14 @@ var ngRepeatDirective = ngDirective({
           key = (collection === array) ? index : array[index];
           value = collection[key];
 
-          // if collection is array and value is object, it can be shifted to allow for position change
-          // if collection is array and value is not object, need to first check whether index is same to
-          // avoid shifting wrong value
-          // if collection is not array, need to always check index to avoid shifting wrong value
-          if (lastOrder.peek(value)) {
-            last = collection === array ?
-              ((isObject(value)) ? lastOrder.shift(value) :
-                (index === lastOrder.peek(value).index ? lastOrder.shift(value) : undefined)) :
-              (index === lastOrder.peek(value).index ? lastOrder.shift(value) : undefined);
-          } else {
-            last = undefined;
-          }
+          // if value is object, it can be shifted to allow for position change
+          // if is not object, need to first check whether index is same to avoid shifting wrong val
+          last = isObject(value)
+              ? lastOrder.shift(value)
+              : (last = lastOrder.peek(value)) && (index === last.index)
+                  ? lastOrder.shift(value)
+                  : undefined;
+
 
           if (last) {
             // if we have already seen this object, then we need to reuse the
@@ -151,12 +147,6 @@ var ngRepeatDirective = ngDirective({
               cursor = last.element;
             }
           } else {
-            if (indexValues.hasOwnProperty(index) && collection !== array) {
-              var preValue = indexValues[index];
-              var v = lastOrder.shift(preValue);
-              v.element.remove();
-              v.scope.$destroy();
-            }
             // new item which we don't know about
             childScope = scope.$new();
           }
@@ -178,16 +168,10 @@ var ngRepeatDirective = ngDirective({
                   index: index
                 };
               nextOrder.push(value, last);
-              indexValues[index] = value;
             });
           }
         }
 
-        var i, l;
-        for (i = 0, l = indexValues.length - length; i < l; i++) {
-          indexValues.pop();
-        }
-
         //shrink children
         for (key in lastOrder) {
           if (lastOrder.hasOwnProperty(key)) {