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 �

Author: nate-thegrate

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,
-          primarySwatch: Colors.purple,
-        );
-      case StockMode.pessimistic:
-        return ThemeData(
-          useMaterial3: false,
-          brightness: Brightness.dark,
-          primarySwatch: Colors.purple,
-        );
-    }
+    return ThemeData(
+      useMaterial3: false,
+      brightness: switch (_configuration.stockMode) {
+        StockMode.optimistic => Brightness.light,
+        StockMode.pessimistic => 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;
-  late final String workingBranch;
-  late final String repoLabel;
-  switch (repoName) {
-    case 'flutter':
-      candidateBranch = state.framework.candidateBranch;
-      workingBranch = state.framework.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.');
-  }
+  final (pb.Repository repository, String repoLabel) = switch (repoName) {
+    'flutter' => (state.framework, 'Framework'),
+    'engine'  => (state.engine, 'Engine'),
+    _ => throw ConductorException('Expected repoName to be one of flutter or engine but got $repoName.'),
+  };
+  final String candidateBranch = repository.candidateBranch;
+  final String workingBranch = repository.workingBranch;
   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) {
-            Widget? child;
-            switch (destination.type) {
-              case CardDemoType.standard:
-                child = TravelDestinationItem(destination: destination, shape: _shape);
-              case CardDemoType.tappable:
-                child = TappableTravelDestinationItem(destination: destination, shape: _shape);
-              case CardDemoType.selectable:
-                child = SelectableTravelDestinationItem(destination: destination, shape: _shape);
-            }
-
-            return Container(
-              margin: const EdgeInsets.only(bottom: 8.0),
-              child: child,
-            );
-          }).toList(),
+          children: <Widget>[
+            for (final TravelDestination destination in destinations)
+              Padding(
+                padding: const EdgeInsets.only(bottom: 8.0),
+                child: switch (destination.type) {
+                  CardDemoType.standard   => TravelDestinationItem(destination: destination, shape: _shape),
+                  CardDemoType.tappable   => TappableTravelDestinationItem(destination: destination, shape: _shape),
+                  CardDemoType.selectable => SelectableTravelDestinationItem(destination: destination, shape: _shape),
+                },
+              ),
+          ],
         ),
       ),
     );

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);
-      switch (textDirection) {
-        case TextDirection.rtl: {
-          final Path path = _notchedCornerPath(outer.middleRect, gapStart + gapPadding - extent!, extent);
-          canvas.drawPath(path, paint);
-          break;
-        }
-        case TextDirection.ltr: {
-          final Path path = _notchedCornerPath(outer.middleRect, gapStart - gapPadding, extent);
-          canvas.drawPath(path, paint);
-          break;
-        }
-        case null:
-          break;
+      final double extent = lerpDouble(0.0, gapExtent + gapPadding * 2.0, gapPercentage)!;
+      if (textDirection != null) {
+        final double start = switch (textDirection) {
+          TextDirection.rtl => gapStart + gapPadding - extent,
+          TextDirection.ltr => gapStart - gapPadding,
+        };
+        canvas.drawPath(_notchedCornerPath(outer.middleRect, start, extent), paint);
       }
     }
   }

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(
-                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,
-                    ),
-                  ),
-                ),
-              ),
+              Expanded(child: Center(child: showAlertButton)),
               if (lastSelectedValue.value != null)
                 Padding(
                   padding: const EdgeInsets.all(16),
                   child: Text(
-                    GalleryLocalizations.of(context)!
-                        .dialogSelectedOption(lastSelectedValue.value!),
+                    localizations.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;
-    switch (type) {
-      case DividerDemoType.horizontal:
-        dividers = _HorizontalDividerDemo();
-      case DividerDemoType.vertical:
-        dividers = _VerticalDividerDemo();
-    }
-
+    final GalleryLocalizations localizations = GalleryLocalizations.of(context)!;
     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) {
-      case PickerDemoType.date:
-        return DateFormat.yMMMd().format(_fromDate.value);
-      case PickerDemoType.time:
-        return _fromTime.value.format(context);
-      case PickerDemoType.range:
-        return '${DateFormat.yMMMd().format(_startDate.value)} - ${DateFormat.yMMMd().format(_endDate.value)}';
-    }
+    final DateFormat yMMMd = DateFormat.yMMMd();
+    return switch (widget.type) {
+      PickerDemoType.date  => yMMMd.format(_fromDate.value),
+      PickerDemoType.time  => _fromTime.value.format(context),
+      PickerDemoType.range => '${yMMMd.format(_startDate.value)} - ${yMMMd.format(_endDate.value)}',
+    };
   }
 
   @override
@@ -199,16 +197,11 @@ class _PickerDemoState extends State<PickerDemo> with RestorationMixin {
                   Text(_labelText),
                   const SizedBox(height: 16),
                   ElevatedButton(
-                    onPressed: () {
-                      switch (widget.type) {
-                        case PickerDemoType.date:
-                          _restorableDatePickerRouteFuture.present();
-                        case PickerDemoType.time:
-                          _restorableTimePickerRouteFuture.present();
-                        case PickerDemoType.range:
-                          _restorableDateRangePickerRouteFuture.present();
-                      }
-                    },
+                    onPressed: () => switch (widget.type) {
+                      PickerDemoType.date  => _restorableDatePickerRouteFuture,
+                      PickerDemoType.time  => _restorableTimePickerRouteFuture,
+                      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(),
+      },
     );
   }
 }