From 6d0b325f7f5b9c1f3cfac9b73c6cd5fc3d1e2af0 Mon Sep 17 00:00:00 2001
From: "R. Merkert" <merkertr@gmail.com>
Date: Tue, 16 Apr 2013 20:09:43 -0400
Subject: [PATCH] fix(angular): do not copy $$hashKey in copy/extend functions.

Copying the $$hashKey as part of copy/extend operations makes little
sense since hashkey is used primarily as an object id, especially in
the context of the ngRepeat directive. This change maintains the
existing $$hashKey of an object that is being copied into (likewise for
extend).
It is not uncommon to take an item in a collection, copy it,
and then append it to the collection. By copying the $$hashKey, this
leads to duplicate object errors with the current ngRepeat.

Closes #1875
---
 src/Angular.js      | 20 ++++++++++++++++
 test/AngularSpec.js | 57 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/src/Angular.js b/src/Angular.js
index bf64c6c27de5..45023d6c64d6 100644
--- a/src/Angular.js
+++ b/src/Angular.js
@@ -215,6 +215,21 @@ function nextUid() {
   return uid.join('');
 }
 
+
+/**
+ * Set or clear the hashkey for an object.
+ * @param obj object 
+ * @param h the hashkey (!truthy to delete the hashkey)
+ */
+function setHashKey(obj, h) {
+  if (h) {
+    obj.$$hashKey = h;
+  }
+  else {
+    delete obj.$$hashKey;
+  }
+}
+
 /**
  * @ngdoc function
  * @name angular.extend
@@ -228,6 +243,7 @@ function nextUid() {
  * @param {...Object} src Source object(s).
  */
 function extend(dst) {
+  var h = dst.$$hashKey;
   forEach(arguments, function(obj){
     if (obj !== dst) {
       forEach(obj, function(value, key){
@@ -235,6 +251,8 @@ function extend(dst) {
       });
     }
   });
+
+  setHashKey(dst,h);
   return dst;
 }
 
@@ -594,12 +612,14 @@ function copy(source, destination){
         destination.push(copy(source[i]));
       }
     } else {
+      var h = destination.$$hashKey;
       forEach(destination, function(value, key){
         delete destination[key];
       });
       for ( var key in source) {
         destination[key] = copy(source[key]);
       }
+      setHashKey(destination,h);
     }
   }
   return destination;
diff --git a/test/AngularSpec.js b/test/AngularSpec.js
index 7f1ab8a32c26..0e5017ad25d9 100644
--- a/test/AngularSpec.js
+++ b/test/AngularSpec.js
@@ -98,6 +98,63 @@ describe('angular', function() {
       src = dst = [2, 4];
       expect(function() { copy(src, dst); }).toThrow("Can't copy equivalent objects or arrays");
     });
+
+    it('should not copy the private $$hashKey', function() {
+      var src,dst;
+      src = {};
+      hashKey(src);
+      dst = copy(src);
+      expect(hashKey(dst)).not.toEqual(hashKey(src));
+    });
+
+    it('should retain the previous $$hashKey', function() {
+      var src,dst,h;
+      src = {};
+      dst = {};
+      // force creation of a hashkey
+      h = hashKey(dst);
+      hashKey(src);
+      dst = copy(src,dst);
+
+      // make sure we don't copy the key
+      expect(hashKey(dst)).not.toEqual(hashKey(src));
+      // make sure we retain the old key
+      expect(hashKey(dst)).toEqual(h);
+    });
+  });
+
+  describe("extend", function() {
+
+    it('should not copy the private $$hashKey', function() {
+      var src,dst;
+      src = {};
+      dst = {};
+      hashKey(src);
+      dst = extend(dst,src);
+      expect(hashKey(dst)).not.toEqual(hashKey(src));
+    });
+
+    it('should retain the previous $$hashKey', function() {
+      var src,dst,h;
+      src = {};
+      dst = {};
+      h = hashKey(dst);
+      hashKey(src);
+      dst = extend(dst,src);
+      // make sure we don't copy the key
+      expect(hashKey(dst)).not.toEqual(hashKey(src));
+      // make sure we retain the old key
+      expect(hashKey(dst)).toEqual(h);
+    });
+
+    it('should work when extending with itself', function() {
+      var src,dst,h;
+      dst = src = {};
+      h = hashKey(dst);
+      dst = extend(dst,src);
+      // make sure we retain the old key
+      expect(hashKey(dst)).toEqual(h);
+    });
   });
 
   describe('shallow copy', function() {