fix(ng-repeat): don't use iterable.length

Author: chirayuk

lib/change_detection/change_detection.dart

@@ -168,6 +168,7 @@ abstract class ChangedKeyValue<K, V> extends MapKeyValue<K, V> {
 abstract class CollectionChangeRecord<V> {
   /** The underlying iterable object */
   Iterable get iterable;
+  int get length;
 
   /** A list of [CollectionItem]s which are in the iteration order. */
   CollectionItem<V> get collectionHead;

lib/change_detection/dirty_checking_change_detector.dart

@@ -795,6 +795,8 @@ class KeyValueRecord<K, V> implements KeyValue<K, V>, AddedKeyValue<K, V>,
 
 class _CollectionChangeRecord<V> implements CollectionChangeRecord<V> {
   Iterable _iterable;
+  int _length;
+
   /** Used to keep track of items during moves. */
   DuplicateMap _items = new DuplicateMap();
 
@@ -836,6 +838,7 @@ class _CollectionChangeRecord<V> implements CollectionChangeRecord<V> {
   }
 
   Iterable get iterable => _iterable;
+  int get length => _length;
 
   bool _check(Iterable collection) {
     _reset();
@@ -849,6 +852,7 @@ class _CollectionChangeRecord<V> implements CollectionChangeRecord<V> {
 
     if (collection is List) {
       List list = collection;
+      _length = list.length;
       for (int index = 0; index < list.length; index++) {
         var item = list[index];
         if (record == null || !identical(item, record.item)) {
@@ -873,6 +877,7 @@ class _CollectionChangeRecord<V> implements CollectionChangeRecord<V> {
         record = record._nextRec;
         index++;
       }
+      _length = index;
     }
 
     _truncate(record);

lib/directive/ng_repeat.dart

@@ -142,7 +142,7 @@ class NgRepeatDirective {
 
   // Computes and executes DOM changes when the item list changes
   void _onChange(CollectionChangeRecord changes) {
-    final int length = changes.iterable.length;
+    final int length = changes.length;
     final rows = new List<_Row>(length);
     final changeFunctions = new List<Function>(length);
     final removedIndexes = <int>[];

test/change_detection/dirty_checking_change_detector_spec.dart

@@ -701,9 +701,11 @@ class CollectionRecordMatcher extends Matcher {
 
   bool checkCollection(CollectionChangeRecord changeRecord, List diffs) {
     var equals = true;
+    int count = 0;
     if (collection != null) {
       CollectionItem collectionItem = changeRecord.collectionHead;
       for (var item in collection) {
+        count++;
         if (collectionItem == null) {
           equals = false;
           diffs.add('collection too short: $item');
@@ -720,6 +722,11 @@ class CollectionRecordMatcher extends Matcher {
         equals = false;
       }
     }
+    var iterableLength = changeRecord.iterable.toList().length;
+    if (iterableLength != count) {
+      diffs.add('collection length mismatched: $iterableLength != $count');
+      equals = false;
+    }
     return equals;
   }
 

test/directive/ng_repeat_spec.dart

@@ -42,6 +42,20 @@ main() {
     });
 
 
+    it(r'should set create a list of items', (Scope scope, Compiler compiler, Injector injector) {
+      scope.context['items'] = [];
+      scope.watch('1', (_, __) {
+        scope.context['items'].add('a');
+        scope.context['items'].add('b');
+      });
+      var element = es('<div><div ng-repeat="item in items">{{item}}</div></div>');
+      ViewFactory viewFactory = compiler(element, directives);
+      View view = viewFactory(injector, element);
+      scope.apply();
+      expect(element).toHaveText('ab');
+    });
+
+
     it(r'should set create a list of items from iterable',
         (Scope scope, Compiler compiler, Injector injector) {
       var element = es('<div><div ng-repeat="item in items">{{item}}</div></div>');