switch expressions: finale (#148711)

### fixes #136139

<br>

<details open> <summary><b>getting sentimental in the PR description</b> (click to collapse)<br><br></summary>

The past 7 months have been quite the journey—I made some huge blunders and some huge accomplishments—a very fun time overall.

I really appreciate the people who took the time to perform code review for my refactoring shenanigans: **christopherfujino**, **andrewkolos**, **LongCatIsLooong**, **gspencergoog**, **loic-sharma**, **Piinks**, **bernaferrari**, **bartekpacia**, **bleroux**, **kevmoo**, **rakudrama**, **XilaiZhang**, **QuncCccccc**, **MominRaza**, and **victorsanni**.

And a huge shoutout to 2 individuals:
- @justinmc, for offering to sponsor me for commit access (words could not describe my excitement)
- @goderbauer, for being super duper proactive and consistent with code review

<br>

</details>

This pull request makes 13 "switch statements → switch expressions" PRs in total, reducing the LOC in this repo by **1,974**!

From now on, I'll make sure to request a test exemption for each refactoring PR 🙂

dev/benchmarks/test_apps/stocks/lib/main.dart

@@ -47,20 +47,14 @@ class StocksAppState extends State<StocksApp> {
   }
 
   ThemeData get theme {
-    switch (_configuration.stockMode) {
-      case StockMode.optimistic:
     return ThemeData(
       useMaterial3: false,
-          brightness: Brightness.light,
+      brightness: switch (_configuration.stockMode) {
+        StockMode.optimistic => Brightness.light,
+        StockMode.pessimistic => Brightness.dark,
+      },
       primarySwatch: Colors.purple,
     );
-      case StockMode.pessimistic:
-        return ThemeData(
-          useMaterial3: false,
-          brightness: Brightness.dark,
-          primarySwatch: Colors.purple,
-        );
-    }
   }
 
   Route<dynamic>? _getRoute(RouteSettings settings) {

dev/conductor/core/lib/src/globals.dart

@@ -152,21 +152,13 @@ String getNewPrLink({
 }) {
   assert(state.releaseChannel.isNotEmpty);
   assert(state.releaseVersion.isNotEmpty);
-  late final String candidateBranch;
+  final (pb.Repository repository, String repoLabel) = switch (repoName) {
-  late final String workingBranch;
+    'flutter' => (state.framework, 'Framework'),
-  late final String repoLabel;
+    'engine'  => (state.engine, 'Engine'),
-  switch (repoName) {
+    _ => throw ConductorException('Expected repoName to be one of flutter or engine but got $repoName.'),
-    case 'flutter':
+  };
-      candidateBranch = state.framework.candidateBranch;
+  final String candidateBranch = repository.candidateBranch;
-      workingBranch = state.framework.workingBranch;
+  final String workingBranch = repository.workingBranch;
-      repoLabel = 'Framework';
-    case 'engine':
-      candidateBranch = state.engine.candidateBranch;
-      workingBranch = state.engine.workingBranch;
-      repoLabel = 'Engine';
-    default:
-      throw ConductorException('Expected repoName to be one of flutter or engine but got $repoName.');
-  }
   assert(candidateBranch.isNotEmpty);
   assert(workingBranch.isNotEmpty);
   final String title = '[flutter_releases] Flutter ${state.releaseChannel} '

dev/integration_tests/flutter_gallery/lib/demo/material/cards_demo.dart

@@ -377,22 +377,17 @@ class _CardsDemoState extends State<CardsDemo> {
         child: ListView(
           primary: true,
           padding: const EdgeInsets.only(top: 8.0, left: 8.0, right: 8.0),
-          children: destinations.map<Widget>((TravelDestination destination) {
+          children: <Widget>[
-            Widget? child;
+            for (final TravelDestination destination in destinations)
-            switch (destination.type) {
+              Padding(
-              case CardDemoType.standard:
+                padding: const EdgeInsets.only(bottom: 8.0),
-                child = TravelDestinationItem(destination: destination, shape: _shape);
+                child: switch (destination.type) {
-              case CardDemoType.tappable:
+                  CardDemoType.standard   => TravelDestinationItem(destination: destination, shape: _shape),
-                child = TappableTravelDestinationItem(destination: destination, shape: _shape);
+                  CardDemoType.tappable   => TappableTravelDestinationItem(destination: destination, shape: _shape),
-              case CardDemoType.selectable:
+                  CardDemoType.selectable => SelectableTravelDestinationItem(destination: destination, shape: _shape),
-                child = SelectableTravelDestinationItem(destination: destination, shape: _shape);
+                },
-            }
+              ),
-
+          ],
-            return Container(
-              margin: const EdgeInsets.only(bottom: 8.0),
-              child: child,
-            );
-          }).toList(),
         ),
       ),
     );

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

@@ -100,20 +100,13 @@ class CutCornersBorder extends OutlineInputBorder {
     if (gapStart == null || gapExtent <= 0.0 || gapPercentage == 0.0) {
       canvas.drawPath(_notchedCornerPath(outer.middleRect), paint);
     } else {
-      final double? extent = lerpDouble(0.0, gapExtent + gapPadding * 2.0, gapPercentage);
+      final double extent = lerpDouble(0.0, gapExtent + gapPadding * 2.0, gapPercentage)!;
-      switch (textDirection) {
+      if (textDirection != null) {
-        case TextDirection.rtl: {
+        final double start = switch (textDirection) {
-          final Path path = _notchedCornerPath(outer.middleRect, gapStart + gapPadding - extent!, extent);
+          TextDirection.rtl => gapStart + gapPadding - extent,
-          canvas.drawPath(path, paint);
+          TextDirection.ltr => gapStart - gapPadding,
-          break;
+        };
-        }
+        canvas.drawPath(_notchedCornerPath(outer.middleRect, start, extent), paint);
-        case TextDirection.ltr: {
-          final Path path = _notchedCornerPath(outer.middleRect, gapStart - gapPadding, extent);
-          canvas.drawPath(path, paint);
-          break;
-        }
-        case null:
-          break;
       }
     }
   }

dev/integration_tests/new_gallery/lib/demos/cupertino/cupertino_alert_demo.dart

@@ -298,37 +298,26 @@ class _CupertinoAlertDemoState extends State<CupertinoAlertDemo>
       ),
       child: Builder(
         builder: (BuildContext context) {
+          final GalleryLocalizations localizations = GalleryLocalizations.of(context)!;
+          final Widget showAlertButton = CupertinoButton.filled(
+            onPressed: () => switch (widget.type) {
+              AlertDemoType.alert            => _alertDialogRoute,
+              AlertDemoType.alertTitle       => _alertWithTitleDialogRoute,
+              AlertDemoType.alertButtons     => _alertWithButtonsDialogRoute,
+              AlertDemoType.alertButtonsOnly => _alertWithButtonsOnlyDialogRoute,
+              AlertDemoType.actionSheet      => _modalPopupRoute,
+            }.present(),
+            child: Text(localizations.cupertinoShowAlert),
+          );
+
           return Column(
             children: <Widget>[
-              Expanded(
+              Expanded(child: Center(child: showAlertButton)),
-                child: Center(
-                  child: CupertinoButton.filled(
-                    onPressed: () {
-                      switch (widget.type) {
-                        case AlertDemoType.alert:
-                          _alertDialogRoute.present();
-                        case AlertDemoType.alertTitle:
-                          _alertWithTitleDialogRoute.present();
-                        case AlertDemoType.alertButtons:
-                          _alertWithButtonsDialogRoute.present();
-                        case AlertDemoType.alertButtonsOnly:
-                          _alertWithButtonsOnlyDialogRoute.present();
-                        case AlertDemoType.actionSheet:
-                          _modalPopupRoute.present();
-                      }
-                    },
-                    child: Text(
-                      GalleryLocalizations.of(context)!.cupertinoShowAlert,
-                    ),
-                  ),
-                ),
-              ),
               if (lastSelectedValue.value != null)
                 Padding(
                   padding: const EdgeInsets.all(16),
                   child: Text(
-                    GalleryLocalizations.of(context)!
+                    localizations.dialogSelectedOption(lastSelectedValue.value!),
-                        .dialogSelectedOption(lastSelectedValue.value!),
                     style: CupertinoTheme.of(context).textTheme.textStyle,
                     textAlign: TextAlign.center,
                   ),

dev/integration_tests/new_gallery/lib/demos/material/button_demo.dart

@@ -24,26 +24,18 @@ class ButtonDemo extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    Widget? buttons;
-    switch (type) {
-      case ButtonDemoType.text:
-        buttons = _TextButtonDemo();
-      case ButtonDemoType.elevated:
-        buttons = _ElevatedButtonDemo();
-      case ButtonDemoType.outlined:
-        buttons = _OutlinedButtonDemo();
-      case ButtonDemoType.toggle:
-        buttons = _ToggleButtonsDemo();
-      case ButtonDemoType.floating:
-        buttons = _FloatingActionButtonDemo();
-    }
-
     return Scaffold(
       appBar: AppBar(
         automaticallyImplyLeading: false,
         title: Text(_title(context)),
       ),
-      body: buttons,
+      body: switch (type) {
+        ButtonDemoType.text     => _TextButtonDemo(),
+        ButtonDemoType.elevated => _ElevatedButtonDemo(),
+        ButtonDemoType.outlined => _OutlinedButtonDemo(),
+        ButtonDemoType.toggle   => _ToggleButtonsDemo(),
+        ButtonDemoType.floating => _FloatingActionButtonDemo(),
+      },
     );
   }
 }

dev/integration_tests/new_gallery/lib/demos/material/chip_demo.dart

@@ -26,24 +26,17 @@ class ChipDemo extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    Widget? buttons;
-    switch (type) {
-      case ChipDemoType.action:
-        buttons = _ActionChipDemo();
-      case ChipDemoType.choice:
-        buttons = _ChoiceChipDemo();
-      case ChipDemoType.filter:
-        buttons = _FilterChipDemo();
-      case ChipDemoType.input:
-        buttons = _InputChipDemo();
-    }
-
     return Scaffold(
       appBar: AppBar(
         automaticallyImplyLeading: false,
         title: Text(_title(context)),
       ),
-      body: buttons,
+      body: switch (type) {
+        ChipDemoType.action => _ActionChipDemo(),
+        ChipDemoType.choice => _ChoiceChipDemo(),
+        ChipDemoType.filter => _FilterChipDemo(),
+        ChipDemoType.input  => _InputChipDemo(),
+      },
     );
   }
 }

dev/integration_tests/new_gallery/lib/demos/material/divider_demo.dart

@@ -11,33 +11,23 @@ class DividerDemo extends StatelessWidget {
 
   final DividerDemoType type;
 
-  String _title(BuildContext context) {
-    switch (type) {
-      case DividerDemoType.horizontal:
-        return GalleryLocalizations.of(context)!.demoDividerTitle;
-      case DividerDemoType.vertical:
-        return GalleryLocalizations.of(context)!.demoVerticalDividerTitle;
-    }
-  }
-
   @override
   Widget build(BuildContext context) {
-    late Widget dividers;
+    final GalleryLocalizations localizations = GalleryLocalizations.of(context)!;
-    switch (type) {
-      case DividerDemoType.horizontal:
-        dividers = _HorizontalDividerDemo();
-      case DividerDemoType.vertical:
-        dividers = _VerticalDividerDemo();
-    }
-
     return Scaffold(
       appBar: AppBar(
         automaticallyImplyLeading: false,
         title: Text(
-          _title(context),
+          switch (type) {
+            DividerDemoType.horizontal => localizations.demoDividerTitle,
+            DividerDemoType.vertical   => localizations.demoVerticalDividerTitle,
+          },
         ),
       ),
-      body: dividers,
+      body: switch (type) {
+        DividerDemoType.horizontal => _HorizontalDividerDemo(),
+        DividerDemoType.vertical   => _VerticalDividerDemo(),
+      },
     );
   }
 }

dev/integration_tests/new_gallery/lib/demos/material/picker_demo.dart

@@ -172,14 +172,12 @@ class _PickerDemoState extends State<PickerDemo> with RestorationMixin {
   }
 
   String get _labelText {
-    switch (widget.type) {
+    final DateFormat yMMMd = DateFormat.yMMMd();
-      case PickerDemoType.date:
+    return switch (widget.type) {
-        return DateFormat.yMMMd().format(_fromDate.value);
+      PickerDemoType.date  => yMMMd.format(_fromDate.value),
-      case PickerDemoType.time:
+      PickerDemoType.time  => _fromTime.value.format(context),
-        return _fromTime.value.format(context);
+      PickerDemoType.range => '${yMMMd.format(_startDate.value)} - ${yMMMd.format(_endDate.value)}',
-      case PickerDemoType.range:
+    };
-        return '${DateFormat.yMMMd().format(_startDate.value)} - ${DateFormat.yMMMd().format(_endDate.value)}';
-    }
   }
 
   @override
@@ -199,16 +197,11 @@ class _PickerDemoState extends State<PickerDemo> with RestorationMixin {
                   Text(_labelText),
                   const SizedBox(height: 16),
                   ElevatedButton(
-                    onPressed: () {
+                    onPressed: () => switch (widget.type) {
-                      switch (widget.type) {
+                      PickerDemoType.date  => _restorableDatePickerRouteFuture,
-                        case PickerDemoType.date:
+                      PickerDemoType.time  => _restorableTimePickerRouteFuture,
-                          _restorableDatePickerRouteFuture.present();
+                      PickerDemoType.range => _restorableDateRangePickerRouteFuture,
-                        case PickerDemoType.time:
+                    }.present(),
-                          _restorableTimePickerRouteFuture.present();
-                        case PickerDemoType.range:
-                          _restorableDateRangePickerRouteFuture.present();
-                      }
-                    },
                     child: Text(
                       GalleryLocalizations.of(context)!.demoPickersShowPicker,
                     ),

dev/integration_tests/new_gallery/lib/demos/material/selection_controls_demo.dart

@@ -27,22 +27,16 @@ class SelectionControlsDemo extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    Widget? controls;
-    switch (type) {
-      case SelectionControlsDemoType.checkbox:
-        controls = _CheckboxDemo();
-      case SelectionControlsDemoType.radio:
-        controls = _RadioDemo();
-      case SelectionControlsDemoType.switches:
-        controls = _SwitchDemo();
-    }
-
     return Scaffold(
       appBar: AppBar(
         automaticallyImplyLeading: false,
         title: Text(_title(context)),
       ),
-      body: controls,
+      body: switch (type) {
+        SelectionControlsDemoType.checkbox => _CheckboxDemo(),
+        SelectionControlsDemoType.radio    => _RadioDemo(),
+        SelectionControlsDemoType.switches => _SwitchDemo(),
+      },
     );
   }
 }

dev/integration_tests/new_gallery/lib/demos/material/sliders_demo.dart

@@ -27,21 +27,16 @@ class SlidersDemo extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    Widget sliders;
-    switch (type) {
-      case SlidersDemoType.sliders:
-        sliders = _Sliders();
-      case SlidersDemoType.rangeSliders:
-        sliders = _RangeSliders();
-      case SlidersDemoType.customSliders:
-        sliders = _CustomSliders();
-    }
     return Scaffold(
       appBar: AppBar(
         automaticallyImplyLeading: false,
         title: Text(_title(context)),
       ),
-      body: sliders,
+      body: switch (type) {
+        SlidersDemoType.sliders       => _Sliders(),
+        SlidersDemoType.rangeSliders  => _RangeSliders(),
+        SlidersDemoType.customSliders => _CustomSliders(),
+      },
     );
   }
 }
@@ -345,25 +340,13 @@ class _CustomRangeThumbShape extends RangeSliderThumbShape {
     );
 
     final double size = _thumbSize * sizeTween.evaluate(enableAnimation);
-    Path thumbPath;
-    switch (textDirection!) {
-      case TextDirection.rtl:
-        switch (thumb!) {
-          case Thumb.start:
-            thumbPath = _rightTriangle(size, center);
-          case Thumb.end:
-            thumbPath = _leftTriangle(size, center);
-        }
-      case TextDirection.ltr:
-        switch (thumb!) {
-          case Thumb.start:
-            thumbPath = _leftTriangle(size, center);
-          case Thumb.end:
-            thumbPath = _rightTriangle(size, center);
-        }
-    }
     canvas.drawPath(
-      thumbPath,
+      switch ((textDirection!, thumb!)) {
+        (TextDirection.rtl, Thumb.start) => _rightTriangle(size, center),
+        (TextDirection.rtl, Thumb.end)   => _leftTriangle(size, center),
+        (TextDirection.ltr, Thumb.start) => _leftTriangle(size, center),
+        (TextDirection.ltr, Thumb.end)   => _rightTriangle(size, center),
+      },
       Paint()..color = colorTween.evaluate(enableAnimation)!,
     );
   }

dev/integration_tests/new_gallery/lib/studies/shrine/supplemental/cut_corners_border.dart

@@ -102,23 +102,12 @@ class CutCornersBorder extends OutlineInputBorder {
     if (gapStart == null || gapExtent <= 0 || gapPercentage == 0) {
       canvas.drawPath(_notchedCornerPath(outer.middleRect), paint);
     } else {
-      final double? extent = lerpDouble(0.0, gapExtent + gapPadding * 2, gapPercentage);
+      final double extent = lerpDouble(0.0, gapExtent + gapPadding * 2, gapPercentage)!;
-      switch (textDirection!) {
+      final double start = switch (textDirection!) {
-        case TextDirection.rtl:
+        TextDirection.rtl => gapStart + gapPadding - extent,
-          {
+        TextDirection.ltr => gapStart - gapPadding,
-            final Path path = _notchedCornerPath(
+      };
-                outer.middleRect, gapStart + gapPadding - extent!, extent);
+      canvas.drawPath(_notchedCornerPath(outer.middleRect, start, extent), paint);
-            canvas.drawPath(path, paint);
-            break;
-          }
-        case TextDirection.ltr:
-          {
-            final Path path = _notchedCornerPath(
-                outer.middleRect, gapStart - gapPadding, extent!);
-            canvas.drawPath(path, paint);
-            break;
-          }
-      }
     }
   }
 }

dev/tools/localization/bin/gen_localizations.dart

@@ -400,17 +400,12 @@ $factoryDeclaration
 ///
 /// Used by [generateGetter] below.
 String generateType(Map<String, dynamic>? attributes) {
-  bool optional = false;
+  final bool optional = attributes?.containsKey('optional') ?? false;
-  String type = 'String';
+  final String type = switch (attributes?['x-flutter-type']) {
-  if (attributes != null) {
+    'icuShortTimePattern' => 'TimeOfDayFormat',
-    optional = attributes.containsKey('optional');
+    'scriptCategory' => 'ScriptCategory',
-    switch (attributes['x-flutter-type'] as String?) {
+    _ => 'String',
-      case 'icuShortTimePattern':
+  };
-        type = 'TimeOfDayFormat';
-      case 'scriptCategory':
-        type = 'ScriptCategory';
-    }
-  }
   return type + (optional ? '?' : '');
 }
 

examples/api/lib/painting/axis_direction/axis_direction.0.dart

@@ -35,33 +35,17 @@ class _MyWidgetState extends State<MyWidget> {
   AxisDirection _axisDirection = AxisDirection.down;
 
   Widget _getArrows() {
-    final Widget arrow;
+    final Widget arrow = switch (_axisDirection) {
-    switch (_axisDirection) {
+      AxisDirection.up    => const Icon(Icons.arrow_upward_rounded),
-      case AxisDirection.up:
+      AxisDirection.down  => const Icon(Icons.arrow_downward_rounded),
-        arrow = const Icon(Icons.arrow_upward_rounded);
+      AxisDirection.left  => const Icon(Icons.arrow_back_rounded),
-        return Row(
+      AxisDirection.right => const Icon(Icons.arrow_forward_rounded),
+    };
+    return Flex(
+      direction: flipAxis(axisDirectionToAxis(_axisDirection)),
       mainAxisAlignment: MainAxisAlignment.center,
       children: <Widget>[arrow, arrow],
     );
-      case AxisDirection.down:
-        arrow = const Icon(Icons.arrow_downward_rounded);
-        return Row(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[arrow, arrow],
-        );
-      case AxisDirection.left:
-        arrow = const Icon(Icons.arrow_back_rounded);
-        return Column(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[arrow, arrow],
-        );
-      case AxisDirection.right:
-        arrow = const Icon(Icons.arrow_forward_rounded);
-        return Column(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[arrow, arrow],
-        );
-    }
   }
 
   void _onAxisDirectionChanged(AxisDirection? axisDirection) {

examples/api/lib/rendering/growth_direction/growth_direction.0.dart

@@ -37,33 +37,17 @@ class _MyWidgetState extends State<MyWidget> {
   AxisDirection _axisDirection = AxisDirection.down;
 
   Widget _getArrows(AxisDirection axisDirection) {
-    final Widget arrow;
+    final Widget arrow = switch (axisDirection) {
-    switch (axisDirection) {
+      AxisDirection.up    => const Icon(Icons.arrow_upward_rounded),
-      case AxisDirection.up:
+      AxisDirection.down  => const Icon(Icons.arrow_downward_rounded),
-        arrow = const Icon(Icons.arrow_upward_rounded);
+      AxisDirection.left  => const Icon(Icons.arrow_back_rounded),
-        return Row(
+      AxisDirection.right => const Icon(Icons.arrow_forward_rounded),
+    };
+    return Flex(
+      direction: flipAxis(axisDirectionToAxis(axisDirection)),
       mainAxisAlignment: MainAxisAlignment.center,
       children: <Widget>[arrow, arrow],
     );
-      case AxisDirection.down:
-        arrow = const Icon(Icons.arrow_downward_rounded);
-        return Row(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[arrow, arrow],
-        );
-      case AxisDirection.left:
-        arrow = const Icon(Icons.arrow_back_rounded);
-        return Column(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[arrow, arrow],
-        );
-      case AxisDirection.right:
-        arrow = const Icon(Icons.arrow_forward_rounded);
-        return Column(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[arrow, arrow],
-        );
-    }
   }
 
   void _onAxisDirectionChanged(AxisDirection? axisDirection) {

examples/api/lib/rendering/scroll_direction/scroll_direction.0.dart

@@ -37,33 +37,17 @@ class _MyWidgetState extends State<MyWidget> {
   AxisDirection _axisDirection = AxisDirection.down;
 
   Widget _getArrows() {
-    final Widget arrow;
+    final Widget arrow = switch (_axisDirection) {
-    switch (_axisDirection) {
+      AxisDirection.up    => const Icon(Icons.arrow_upward_rounded),
-      case AxisDirection.up:
+      AxisDirection.down  => const Icon(Icons.arrow_downward_rounded),
-        arrow = const Icon(Icons.arrow_upward_rounded);
+      AxisDirection.left  => const Icon(Icons.arrow_back_rounded),
-        return Row(
+      AxisDirection.right => const Icon(Icons.arrow_forward_rounded),
+    };
+    return Flex(
+      direction: flipAxis(axisDirectionToAxis(_axisDirection)),
       mainAxisAlignment: MainAxisAlignment.center,
       children: <Widget>[arrow, arrow],
     );
-      case AxisDirection.down:
-        arrow = const Icon(Icons.arrow_downward_rounded);
-        return Row(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[arrow, arrow],
-        );
-      case AxisDirection.left:
-        arrow = const Icon(Icons.arrow_back_rounded);
-        return Column(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[arrow, arrow],
-        );
-      case AxisDirection.right:
-        arrow = const Icon(Icons.arrow_forward_rounded);
-        return Column(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[arrow, arrow],
-        );
-    }
   }
 
   void _onAxisDirectionChanged(AxisDirection? axisDirection) {

examples/api/lib/widgets/overlay/overlay.0.dart

@@ -39,6 +39,24 @@ class _OverlayExampleState extends State<OverlayExample> {
 
     assert(overlayEntry == null);
 
+    Widget builder(BuildContext context) {
+      final (String label, Color? color) = switch (currentPageIndex) {
+        0 => ('Explore page', Colors.red),
+        1 => ('Commute page', Colors.green),
+        2 => ('Saved page', Colors.orange),
+        _ => ('No page selected.', null),
+      };
+      if (color == null) {
+        return Text(label);
+      }
+      return Column(
+        children: <Widget>[
+          Text(label, style: TextStyle(color: color)),
+          Icon(Icons.arrow_downward, color: color),
+        ],
+      );
+    }
+
     overlayEntry = OverlayEntry(
       // Create a new OverlayEntry.
       builder: (BuildContext context) {
@@ -58,57 +76,7 @@ class _OverlayExampleState extends State<OverlayExample> {
                 mainAxisSize: MainAxisSize.min,
                 children: <Widget>[
                   const Text('Tap here for'),
-                  Builder(builder: (BuildContext context) {
+                  Builder(builder: builder),
-                    switch (currentPageIndex) {
-                      case 0:
-                        return const Column(
-                          children: <Widget>[
-                            Text(
-                              'Explore page',
-                              style: TextStyle(
-                                color: Colors.red,
-                              ),
-                            ),
-                            Icon(
-                              Icons.arrow_downward,
-                              color: Colors.red,
-                            ),
-                          ],
-                        );
-                      case 1:
-                        return const Column(
-                          children: <Widget>[
-                            Text(
-                              'Commute page',
-                              style: TextStyle(
-                                color: Colors.green,
-                              ),
-                            ),
-                            Icon(
-                              Icons.arrow_downward,
-                              color: Colors.green,
-                            ),
-                          ],
-                        );
-                      case 2:
-                        return const Column(
-                          children: <Widget>[
-                            Text(
-                              'Saved page',
-                              style: TextStyle(
-                                color: Colors.orange,
-                              ),
-                            ),
-                            Icon(
-                              Icons.arrow_downward,
-                              color: Colors.orange,
-                            ),
-                          ],
-                        );
-                      default:
-                        return const Text('No page selected.');
-                    }
-                  }),
                   SizedBox(
                     width: MediaQuery.of(context).size.width / 3,
                     height: 80.0,

packages/flutter/lib/src/cupertino/scrollbar.dart

@@ -199,18 +199,13 @@ class _CupertinoScrollbarState extends RawScrollbarState<CupertinoScrollbar> {
     }
     _thicknessAnimationController.reverse();
     super.handleThumbPressEnd(localPosition, velocity);
-    switch (direction) {
+    final (double axisPosition, double axisVelocity) = switch (direction) {
-      case Axis.vertical:
+      Axis.horizontal => (localPosition.dx, velocity.pixelsPerSecond.dx),
-        if (velocity.pixelsPerSecond.dy.abs() < 10 &&
+      Axis.vertical   => (localPosition.dy, velocity.pixelsPerSecond.dy),
-          (localPosition.dy - _pressStartAxisPosition).abs() > 0) {
+    };
+    if (axisPosition != _pressStartAxisPosition && axisVelocity.abs() < 10) {
       HapticFeedback.mediumImpact();
     }
-      case Axis.horizontal:
-        if (velocity.pixelsPerSecond.dx.abs() < 10 &&
-          (localPosition.dx - _pressStartAxisPosition).abs() > 0) {
-          HapticFeedback.mediumImpact();
-        }
-    }
   }
 
   @override

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

@@ -560,20 +560,17 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
 
   bool _previouslyOpened = false;
 
+  int get _directionFactor {
+    return switch ((Directionality.of(context), widget.alignment)) {
+      (TextDirection.rtl, DrawerAlignment.start) => -1,
+      (TextDirection.rtl, DrawerAlignment.end)   =>  1,
+      (TextDirection.ltr, DrawerAlignment.start) =>  1,
+      (TextDirection.ltr, DrawerAlignment.end)   => -1,
+    };
+  }
+
   void _move(DragUpdateDetails details) {
-    double delta = details.primaryDelta! / _width;
+    _controller.value += details.primaryDelta! / _width * _directionFactor;
-    switch (widget.alignment) {
-      case DrawerAlignment.start:
-        break;
-      case DrawerAlignment.end:
-        delta = -delta;
-    }
-    switch (Directionality.of(context)) {
-      case TextDirection.rtl:
-        _controller.value -= delta;
-      case TextDirection.ltr:
-        _controller.value += delta;
-    }
 
     final bool opened = _controller.value > 0.5;
     if (opened != _previouslyOpened && widget.drawerCallback != null) {
@@ -586,22 +583,12 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
     if (_controller.isDismissed) {
       return;
     }
-    if (details.velocity.pixelsPerSecond.dx.abs() >= _kMinFlingVelocity) {
+    final double xVelocity = details.velocity.pixelsPerSecond.dx;
-      double visualVelocity = details.velocity.pixelsPerSecond.dx / _width;
+    if (xVelocity.abs() >= _kMinFlingVelocity) {
-      switch (widget.alignment) {
+      final double visualVelocity = xVelocity / _width * _directionFactor;
-        case DrawerAlignment.start:
+
-          break;
-        case DrawerAlignment.end:
-          visualVelocity = -visualVelocity;
-      }
-      switch (Directionality.of(context)) {
-        case TextDirection.rtl:
-          _controller.fling(velocity: -visualVelocity);
-          widget.drawerCallback?.call(visualVelocity < 0.0);
-        case TextDirection.ltr:
       _controller.fling(velocity: visualVelocity);
       widget.drawerCallback?.call(visualVelocity > 0.0);
-      }
     } else if (_controller.value < 0.5) {
       close();
     } else {

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

@@ -539,15 +539,12 @@ class OutlineInputBorder extends InputBorder {
       canvas.drawRRect(center, paint);
     } else {
       final double extent = lerpDouble(0.0, gapExtent + gapPadding * 2.0, gapPercentage)!;
-      switch (textDirection!) {
+      final double start = switch (textDirection!) {
-        case TextDirection.rtl:
+        TextDirection.rtl => gapStart + gapPadding - extent,
-          final Path path = _gapBorderPath(canvas, center, math.max(0.0, gapStart + gapPadding - extent), extent);
+        TextDirection.ltr => gapStart - gapPadding,
+      };
+      final Path path = _gapBorderPath(canvas, center, math.max(0.0, start), extent);
       canvas.drawPath(path, paint);
-
-        case TextDirection.ltr:
-          final Path path = _gapBorderPath(canvas, center, math.max(0.0, gapStart - gapPadding), extent);
-          canvas.drawPath(path, paint);
-      }
     }
   }
 

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

@@ -456,36 +456,20 @@ class _StepperState extends State<Stepper> with TickerProviderStateMixin {
 
   Widget _buildCircleChild(int index, bool oldState) {
     final StepState state = oldState ? _oldStates[index]! : widget.steps[index].state;
-    final bool isDarkActive = _isDark() && widget.steps[index].isActive;
+    if (widget.stepIconBuilder?.call(index, state) case final Widget icon) {
-    final Widget? icon = widget.stepIconBuilder?.call(index, state);
-    if (icon != null) {
       return icon;
     }
     TextStyle? textStyle = _stepStyle(index)?.indexStyle;
+    final bool isDarkActive = _isDark() && widget.steps[index].isActive;
+    final Color iconColor = isDarkActive ? _kCircleActiveDark : _kCircleActiveLight;
     textStyle ??= isDarkActive ? _kStepStyle.copyWith(color: Colors.black87) : _kStepStyle;
 
-    switch (state) {
+    return switch (state) {
-      case StepState.indexed:
+      StepState.indexed || StepState.disabled => Text('${index + 1}', style: textStyle),
-      case StepState.disabled:
+      StepState.editing  => Icon(Icons.edit, color: iconColor, size: 18.0),
-        return Text(
+      StepState.complete => Icon(Icons.check, color: iconColor, size: 18.0),
-          '${index + 1}',
+      StepState.error    => const Center(child: Text('!', style: _kStepStyle)),
-          style: textStyle,
+    };
-        );
-      case StepState.editing:
-        return Icon(
-          Icons.edit,
-          color: isDarkActive ? _kCircleActiveDark : _kCircleActiveLight,
-          size: 18.0,
-        );
-      case StepState.complete:
-        return Icon(
-          Icons.check,
-          color: isDarkActive ? _kCircleActiveDark : _kCircleActiveLight,
-          size: 18.0,
-        );
-      case StepState.error:
-        return const Center(child: Text('!', style: _kStepStyle));
-    }
   }
 
   Color _circleColor(int index) {

packages/flutter/lib/src/widgets/focus_traversal.dart

@@ -705,25 +705,14 @@ mixin DirectionalFocusTraversalPolicyMixin on FocusTraversalPolicy {
 
   @override
   FocusNode? findFirstFocusInDirection(FocusNode currentNode, TraversalDirection direction) {
-    switch (direction) {
-      case TraversalDirection.up:
-        // Find the bottom-most node so we can go up from there.
-        return _sortAndFindInitial(currentNode, vertical: true, first: false);
-      case TraversalDirection.down:
-        // Find the top-most node so we can go down from there.
-        return _sortAndFindInitial(currentNode, vertical: true, first: true);
-      case TraversalDirection.left:
-        // Find the right-most node so we can go left from there.
-        return _sortAndFindInitial(currentNode, vertical: false, first: false);
-      case TraversalDirection.right:
-        // Find the left-most node so we can go right from there.
-        return _sortAndFindInitial(currentNode, vertical: false, first: true);
-    }
-  }
-
-  FocusNode? _sortAndFindInitial(FocusNode currentNode, {required bool vertical, required bool first}) {
     final Iterable<FocusNode> nodes = currentNode.nearestScope!.traversalDescendants;
     final List<FocusNode> sorted = nodes.toList();
+    final (bool vertical, bool first) = switch (direction) {
+      TraversalDirection.up    => (true, false),  // Start with the bottom-most node.
+      TraversalDirection.down  => (true, true),   // Start with the topmost node.
+      TraversalDirection.left  => (false, false), // Start with the rightmost node.
+      TraversalDirection.right => (false, true),  // Start with the leftmost node.
+    };
     mergeSort<FocusNode>(sorted, compare: (FocusNode a, FocusNode b) {
       if (vertical) {
         if (first) {
@@ -740,11 +729,7 @@ mixin DirectionalFocusTraversalPolicyMixin on FocusTraversalPolicy {
       }
     });
 
-    if (sorted.isNotEmpty) {
+    return sorted.firstOrNull;
-      return sorted.first;
-    }
-
-    return null;
   }
 
   static int _verticalCompare(Offset target, Offset a, Offset b) {
@@ -849,17 +834,11 @@ mixin DirectionalFocusTraversalPolicyMixin on FocusTraversalPolicy {
     Iterable<FocusNode> nodes,
   ) {
     assert(direction == TraversalDirection.left || direction == TraversalDirection.right);
-    final Iterable<FocusNode> filtered;
+    final List<FocusNode> sorted = nodes.where(switch (direction) {
-    switch (direction) {
+      TraversalDirection.left  => (FocusNode node) => node.rect != target && node.rect.center.dx <= target.left,
-      case TraversalDirection.left:
+      TraversalDirection.right => (FocusNode node) => node.rect != target && node.rect.center.dx >= target.right,
-        filtered = nodes.where((FocusNode node) => node.rect != target && node.rect.center.dx <= target.left);
+      TraversalDirection.up || TraversalDirection.down => throw ArgumentError('Invalid direction $direction'),
-      case TraversalDirection.right:
+    }).toList();
-        filtered = nodes.where((FocusNode node) => node.rect != target && node.rect.center.dx >= target.right);
-      case TraversalDirection.up:
-      case TraversalDirection.down:
-        throw ArgumentError('Invalid direction $direction');
-    }
-    final List<FocusNode> sorted = filtered.toList();
     // Sort all nodes from left to right.
     mergeSort<FocusNode>(sorted, compare: (FocusNode a, FocusNode b) => a.rect.center.dx.compareTo(b.rect.center.dx));
     return sorted;
@@ -874,17 +853,11 @@ mixin DirectionalFocusTraversalPolicyMixin on FocusTraversalPolicy {
     Iterable<FocusNode> nodes,
   ) {
     assert(direction == TraversalDirection.up || direction == TraversalDirection.down);
-    final Iterable<FocusNode> filtered;
+    final List<FocusNode> sorted = nodes.where(switch (direction) {
-    switch (direction) {
+      TraversalDirection.up   => (FocusNode node) => node.rect != target && node.rect.center.dy <= target.top,
-      case TraversalDirection.up:
+      TraversalDirection.down => (FocusNode node) => node.rect != target && node.rect.center.dy >= target.bottom,
-        filtered = nodes.where((FocusNode node) => node.rect != target && node.rect.center.dy <= target.top);
+      TraversalDirection.left || TraversalDirection.right => throw ArgumentError('Invalid direction $direction'),
-      case TraversalDirection.down:
+    }).toList();
-        filtered = nodes.where((FocusNode node) => node.rect != target && node.rect.center.dy >= target.bottom);
-      case TraversalDirection.left:
-      case TraversalDirection.right:
-        throw ArgumentError('Invalid direction $direction');
-    }
-    final List<FocusNode> sorted = filtered.toList();
     mergeSort<FocusNode>(sorted, compare: (FocusNode a, FocusNode b) => a.rect.center.dy.compareTo(b.rect.center.dy));
     return sorted;
   }