use_is_even_rather_than_modulo (#68301)

analysis_options.yaml

@@ -216,7 +216,7 @@ linter:
     # - unsafe_html # not yet tested
     - use_full_hex_values_for_flutter_colors
     # - use_function_type_syntax_for_parameters # not yet tested
-    # - use_is_even_rather_than_modulo # not yet tested
+    - use_is_even_rather_than_modulo
     # - use_key_in_widget_constructors # not yet tested
     - use_late_for_private_fields_and_variables
     # - use_raw_strings # not yet tested

dev/benchmarks/complex_layout/lib/main.dart

@@ -111,7 +111,7 @@ class ComplexLayoutState extends State<ComplexLayout> {
               key: const Key('complex-scroll'), // this key is used by the driver test
               controller: ScrollController(),  // So that the scroll offset can be tracked
               itemBuilder: (BuildContext context, int index) {
-                if (index % 2 == 0)
+                if (index.isEven)
                   return FancyImageItem(index, key: PageStorageKey<int>(index));
                 else
                   return FancyGalleryItem(index, key: PageStorageKey<int>(index));

dev/benchmarks/macrobenchmarks/lib/src/multi_widget_construction.dart

@@ -70,7 +70,7 @@ class _MultiWidgetConstructTableState extends State<MultiWidgetConstructTable>
                     // This implementation rebuild the widget tree for every
                     // frame, and is intentionally designed of poor performance
                     // for benchmark purposes.
-                    return counter % 2 == 0
+                    return counter.isEven
                         ? Container(
                             // This key forces rebuilding the element
                             key: ValueKey<int>(widgetCounter + label),

dev/benchmarks/macrobenchmarks/lib/src/picture_cache.dart

@@ -132,7 +132,7 @@ class ListItem extends StatelessWidget {
           ),
         ),
         Image.asset(
-          index % 2 == 0 ? 'food/butternut_squash_soup.png' : 'food/cherry_pie.png',
+          index.isEven ? 'food/butternut_squash_soup.png' : 'food/cherry_pie.png',
           package: 'flutter_gallery_assets',
           fit: BoxFit.cover,
           width: 110,

dev/benchmarks/macrobenchmarks/lib/src/web/bench_child_layers.dart

@@ -69,7 +69,7 @@ class BenchUpdateManyChildLayers extends SceneBuilderRecorder {
         final double offsetY = row * cellSize.height;
         // Retain every other layer, so we exercise the update path 50% of the
         // time and the retain path the other 50%.
-        final bool shouldRetain = oldLayer != null && (row + col) % 2 == 0;
+        final bool shouldRetain = oldLayer != null && (row + col).isEven;
         if (shouldRetain) {
           sceneBuilder.addRetained(oldLayer);
         } else {

dev/benchmarks/microbenchmarks/lib/language/sync_star_semantics_bench.dart

@@ -21,7 +21,7 @@ void main() {
       data.add(
         InlineSpanSemanticsInformation(words[i], isPlaceholder: false),
       );
-    } else if (i % 2 == 0) {
+    } else if (i.isEven) {
       data.add(
         InlineSpanSemanticsInformation(words[i], isPlaceholder: true),
       );

dev/benchmarks/microbenchmarks/lib/stocks/layout_bench.dart

@@ -46,7 +46,7 @@ Future<void> main() async {
 
     watch.start();
     while (watch.elapsed < kBenchmarkTime) {
-      renderView.configuration = (iterations % 2 == 0) ? big : small;
+      renderView.configuration = iterations.isEven ? big : small;
       await tester.pumpBenchmark(Duration(milliseconds: iterations * 16));
       iterations += 1;
     }

dev/devicelab/lib/tasks/perf_tests.dart

@@ -1376,7 +1376,7 @@ class ReportedDurationTest {
 class ListStatistics {
   factory ListStatistics(Iterable<int> data) {
     assert(data.isNotEmpty);
-    assert(data.length % 2 == 1);
+    assert(data.length.isOdd);
     final List<int> sortedData = data.toList()..sort();
     return ListStatistics._(
       sortedData.first,

dev/integration_tests/flutter_gallery/lib/demo/shrine/supplemental/asymmetric_view.dart

@@ -28,7 +28,7 @@ class AsymmetricView extends StatelessWidget {
     return List<Container>.generate(_listItemCount(products.length), (int index) {
       double width = .59 * MediaQuery.of(context).size.width;
       Widget column;
-      if (index % 2 == 0) {
+      if (index.isEven) {
         /// Even cases
         final int bottom = _evenCasesIndex(index);
         column = TwoProductCardColumn(

packages/flutter/lib/src/animation/animation_controller.dart

@@ -864,7 +864,7 @@ class _RepeatingSimulation extends Simulation {
 
     final double totalTimeInSeconds = timeInSeconds + _initialT;
     final double t = (totalTimeInSeconds / _periodInSeconds) % 1.0;
-    final bool _isPlayingReverse = (totalTimeInSeconds ~/ _periodInSeconds) % 2 == 1;
+    final bool _isPlayingReverse = (totalTimeInSeconds ~/ _periodInSeconds).isOdd;
 
     if (reverse && _isPlayingReverse) {
       directionSetter(_AnimationDirection.reverse);

packages/flutter/lib/src/material/mergeable_material.dart

@@ -711,7 +711,7 @@ class _RenderMergeableMaterialListBody extends RenderListBody {
     while (child != null) {
       final ListBodyParentData childParentData = child.parentData! as ListBodyParentData;
       final Rect rect = (childParentData.offset + offset) & child.size;
-      if (i % 2 == 0)
+      if (i.isEven)
         _paintShadows(context.canvas, rect);
       child = childParentData.nextSibling;
 

packages/flutter/lib/src/rendering/rotated_box.dart

@@ -42,7 +42,7 @@ class RenderRotatedBox extends RenderBox with RenderObjectWithChildMixin<RenderB
     markNeedsLayout();
   }
 
-  bool get _isVertical => quarterTurns % 2 == 1;
+  bool get _isVertical => quarterTurns.isOdd;
 
   @override
   double computeMinIntrinsicWidth(double height) {

packages/flutter/test/foundation/caching_iterable_test.dart

@@ -55,7 +55,7 @@ void main() {
     final Iterable<int> integers = CachingIterable<int>(range(1, 5).iterator);
     expect(yieldCount, equals(0));
 
-    final Iterable<int> evens = integers.where((int i) => i % 2 == 0);
+    final Iterable<int> evens = integers.where((int i) => i.isEven);
     expect(yieldCount, equals(0));
 
     expect(evens.first, equals(2));

packages/flutter/test/widgets/automatic_keep_alive_test.dart

@@ -515,7 +515,7 @@ void main() {
         addSemanticIndexes: false,
         itemCount: 250,
         itemBuilder: (BuildContext context, int index) {
-          if (index % 2 == 0) {
+          if (index.isEven) {
             return _AlwaysKeepAlive(
               key: GlobalObjectKey<_AlwaysKeepAliveState>(index),
             );

packages/flutter/test/widgets/list_view_viewporting_test.dart

@@ -509,7 +509,7 @@ void main() {
               itemBuilder: (_, int i) => Container(
                 height: 200.0,
                 width: 200.0,
-                color: i % 2 == 0 ? Colors.black : Colors.red,
+                color: i.isEven ? Colors.black : Colors.red,
               ),
             ),
           ),

packages/flutter/test/widgets/page_view_test.dart

@@ -393,7 +393,7 @@ void main() {
           itemBuilder: (BuildContext context, int index) {
             return Container(
               height: 200.0,
-              color: index % 2 == 0
+              color: index.isEven
                 ? const Color(0xFF0000FF)
                 : const Color(0xFF00FF00),
               child: Text(kStates[index]),
@@ -499,7 +499,7 @@ void main() {
           itemBuilder: (BuildContext context, int index) {
             return Container(
               height: 200.0,
-              color: index % 2 == 0
+              color: index.isEven
                 ? const Color(0xFF0000FF)
                 : const Color(0xFF00FF00),
               child: Text(kStates[index]),
@@ -543,7 +543,7 @@ void main() {
           itemBuilder: (BuildContext context, int index) {
             return Container(
               height: 200.0,
-              color: index % 2 == 0
+              color: index.isEven
                 ? const Color(0xFF0000FF)
                 : const Color(0xFF00FF00),
               child: Text(kStates[index]),
@@ -576,7 +576,7 @@ void main() {
             itemBuilder: (BuildContext context, int index) {
               return Container(
                 height: 200.0,
-                color: index % 2 == 0
+                color: index.isEven
                   ? const Color(0xFF0000FF)
                   : const Color(0xFF00FF00),
                 child: Text(kStates[index]),
@@ -615,7 +615,7 @@ void main() {
             itemBuilder: (BuildContext context, int index) {
               return Container(
                 height: 200.0,
-                color: index % 2 == 0
+                color: index.isEven
                   ? const Color(0xFF0000FF)
                   : const Color(0xFF00FF00),
                   child: Text(index.toString()),

packages/flutter/test/widgets/scrollable_dispose_test.dart

@@ -49,7 +49,7 @@ void main() {
                   controller: controller,
                   itemBuilder: (BuildContext context, int index) {
                     return Container(
-                      color: index % 2 == 0 ? Colors.red : Colors.green,
+                      color: index.isEven ? Colors.red : Colors.green,
                       height: 200.0,
                       child: Text('Hello $index'),
                     );

packages/flutter/test/widgets/semantics_keep_alive_offstage_test.dart

@@ -99,7 +99,7 @@ Widget _buildTestWidget({
               controller: controller,
               children: List<Widget>.generate(10, (int i) {
                 return Container(
-                  color: i % 2 == 0 ? Colors.red : Colors.blue,
+                  color: i.isEven ? Colors.red : Colors.blue,
                   height: 250.0,
                   child: Text('Item $i'),
                 );

packages/flutter/test/widgets/slivers_appbar_floating_pinned_test.dart

@@ -72,7 +72,7 @@ void main() {
                     (BuildContext _, int index) {
                       return Container(
                         height: 100.0,
-                        color: index % 2 == 0 ? Colors.red : Colors.yellow,
+                        color: index.isEven ? Colors.red : Colors.yellow,
                         child: Text('Tile $index'),
                       );
                     },

packages/flutter/test/widgets/slivers_test.dart

@@ -889,10 +889,10 @@ void main() {
                   (BuildContext context, int index) {
                   return Container(
                     child: Material(
-                      color: index % 2 == 0 ? Colors.yellow : Colors.red,
+                      color: index.isEven ? Colors.yellow : Colors.red,
                       child: InkWell(
                         onTap: () {
-                          index % 2 == 0 ? firstTapped++ : secondTapped++;
+                          index.isEven ? firstTapped++ : secondTapped++;
                         },
                         child: Text('Index $index'),
                       ),

packages/flutter/test/widgets/transformed_scrollable_test.dart

@@ -26,7 +26,7 @@ void main() {
                 itemBuilder: (BuildContext context, int index) {
                   return Container(
                     height: 100.0,
-                    color: index % 2 == 0 ? Colors.blue : Colors.red,
+                    color: index.isEven ? Colors.blue : Colors.red,
                     child: Text('Tile $index'),
                   );
                 },
@@ -70,7 +70,7 @@ void main() {
                 itemBuilder: (BuildContext context, int index) {
                   return Container(
                     height: 100.0,
-                    color: index % 2 == 0 ? Colors.blue : Colors.red,
+                    color: index.isEven ? Colors.blue : Colors.red,
                     child: Text('Tile $index'),
                   );
                 },
@@ -114,7 +114,7 @@ void main() {
                 itemBuilder: (BuildContext context, int index) {
                   return Container(
                     height: 100.0,
-                    color: index % 2 == 0 ? Colors.blue : Colors.red,
+                    color: index.isEven ? Colors.blue : Colors.red,
                     child: Text('Tile $index'),
                   );
                 },
@@ -156,7 +156,7 @@ void main() {
                 itemBuilder: (BuildContext context, int index) {
                   return Container(
                     height: 100.0,
-                    color: index % 2 == 0 ? Colors.blue : Colors.red,
+                    color: index.isEven ? Colors.blue : Colors.red,
                     child: Text('Tile $index'),
                   );
                 },

packages/flutter_test/test/event_simulation_test.dart

@@ -36,7 +36,7 @@ void main() {
 
       expect(events.length, 8);
       for (int i = 0; i < events.length; ++i) {
-        final bool isEven = i % 2 == 0;
+        final bool isEven = i.isEven;
         if (isEven) {
           expect(events[i].runtimeType, equals(RawKeyDownEvent));
         } else {