Refactoring if chains into switch statements (#144905)

Based on issue #144903, this PR aims to bring the codebase more in line with the [Flutter repo style guide](https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#avoid-using-if-chains-or--or--with-enum-values): > #### Avoid using `if` chains or `?:` or `==` with enum values <br> This change unfortunately increases the total line length, but it also improves readability.
flutter · Mar 11, 2024 · 26e379e · 26e379e
1 parent 187ec75
commit 26e379e
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diff --git a/dev/integration_tests/flutter_gallery/lib/demo/material/bottom_navigation_demo.dart b/dev/integration_tests/flutter_gallery/lib/demo/material/bottom_navigation_demo.dart
@@ -40,14 +40,15 @@ class NavigationIconView {
 
  FadeTransition transition(BottomNavigationBarType type, BuildContext context) {
  Color? iconColor;
- if (type == BottomNavigationBarType.shifting) {
- iconColor = _color;
- } else {
- final ThemeData theme = Theme.of(context);
- final ColorScheme colorScheme = theme.colorScheme;
- iconColor = theme.brightness == Brightness.light
- ? colorScheme.primary
- : colorScheme.secondary;
+ switch (type) {
+ case BottomNavigationBarType.shifting:
+ iconColor = _color;
+ case BottomNavigationBarType.fixed:
+ final ThemeData theme = Theme.of(context);
+ iconColor = switch (theme.brightness) {
+ Brightness.light => theme.colorScheme.primary,
+ Brightness.dark => theme.colorScheme.secondary,
+ };
  }
 
  return FadeTransition(

diff --git a/dev/manual_tests/lib/overlay_geometry.dart b/dev/manual_tests/lib/overlay_geometry.dart
@@ -37,13 +37,16 @@ class _MarkerPainter extends CustomPainter {
  ..color = const Color(0xFFFFFFFF)
  ..style = PaintingStyle.stroke
  ..strokeWidth = 1.0;
- if (type == MarkerType.topLeft) {
- canvas.drawLine(Offset(r, r), Offset(r + r - 1.0, r), paint);
- canvas.drawLine(Offset(r, r), Offset(r, r + r - 1.0), paint);
- }
- if (type == MarkerType.bottomRight) {
- canvas.drawLine(Offset(r, r), Offset(1.0, r), paint);
- canvas.drawLine(Offset(r, r), Offset(r, 1.0), paint);
+
+ switch (type) {
+ case MarkerType.topLeft:
+ canvas.drawLine(Offset(r, r), Offset(r + r - 1.0, r), paint);
+ canvas.drawLine(Offset(r, r), Offset(r, r + r - 1.0), paint);
+ case MarkerType.bottomRight:
+ canvas.drawLine(Offset(r, r), Offset(1.0, r), paint);
+ canvas.drawLine(Offset(r, r), Offset(r, 1.0), paint);
+ case MarkerType.touch:
+ break;
  }
  }
 

diff --git a/examples/api/lib/material/bottom_app_bar/bottom_app_bar.2.dart b/examples/api/lib/material/bottom_app_bar/bottom_app_bar.2.dart
@@ -41,11 +41,13 @@ class _BottomAppBarDemoState extends State<BottomAppBarDemo> {
  _isVisible ? FloatingActionButtonLocation.endContained : FloatingActionButtonLocation.endFloat;
 
  void _listen() {
- final ScrollDirection direction = _controller.position.userScrollDirection;
- if (direction == ScrollDirection.forward) {
- _show();
- } else if (direction == ScrollDirection.reverse) {
- _hide();
+ switch (_controller.position.userScrollDirection) {
+ case ScrollDirection.idle:
+ break;
+ case ScrollDirection.forward:
+ _show();
+ case ScrollDirection.reverse:
+ _hide();
  }
  }
 

diff --git a/packages/flutter/lib/src/cupertino/date_picker.dart b/packages/flutter/lib/src/cupertino/date_picker.dart
@@ -1021,25 +1021,29 @@ class _CupertinoDatePickerDateTimeState extends State<CupertinoDatePicker> {
 
  // Adds am/pm column if the picker is not using 24h format.
  if (!widget.use24hFormat) {
- if (localizations.datePickerDateTimeOrder == DatePickerDateTimeOrder.date_time_dayPeriod
- || localizations.datePickerDateTimeOrder == DatePickerDateTimeOrder.time_dayPeriod_date) {
- pickerBuilders.add(_buildAmPmPicker);
- columnWidths.add(_getEstimatedColumnWidth(_PickerColumnType.dayPeriod));
- } else {
- pickerBuilders.insert(0, _buildAmPmPicker);
- columnWidths.insert(0, _getEstimatedColumnWidth(_PickerColumnType.dayPeriod));
+ switch (localizations.datePickerDateTimeOrder) {
+ case DatePickerDateTimeOrder.date_time_dayPeriod:
+ case DatePickerDateTimeOrder.time_dayPeriod_date:
+ pickerBuilders.add(_buildAmPmPicker);
+ columnWidths.add(_getEstimatedColumnWidth(_PickerColumnType.dayPeriod));
+ case DatePickerDateTimeOrder.date_dayPeriod_time:
+ case DatePickerDateTimeOrder.dayPeriod_time_date:
+ pickerBuilders.insert(0, _buildAmPmPicker);
+ columnWidths.insert(0, _getEstimatedColumnWidth(_PickerColumnType.dayPeriod));
  }
  }
 
  // Adds medium date column if the picker's mode is date and time.
  if (widget.mode == CupertinoDatePickerMode.dateAndTime) {
- if (localizations.datePickerDateTimeOrder == DatePickerDateTimeOrder.time_dayPeriod_date
- || localizations.datePickerDateTimeOrder == DatePickerDateTimeOrder.dayPeriod_time_date) {
- pickerBuilders.add(_buildMediumDatePicker);
- columnWidths.add(_getEstimatedColumnWidth(_PickerColumnType.date));
- } else {
- pickerBuilders.insert(0, _buildMediumDatePicker);
- columnWidths.insert(0, _getEstimatedColumnWidth(_PickerColumnType.date));
+ switch (localizations.datePickerDateTimeOrder) {
+ case DatePickerDateTimeOrder.time_dayPeriod_date:
+ case DatePickerDateTimeOrder.dayPeriod_time_date:
+ pickerBuilders.add(_buildMediumDatePicker);
+ columnWidths.add(_getEstimatedColumnWidth(_PickerColumnType.date));
+ case DatePickerDateTimeOrder.date_time_dayPeriod:
+ case DatePickerDateTimeOrder.date_dayPeriod_time:
+ pickerBuilders.insert(0, _buildMediumDatePicker);
+ columnWidths.insert(0, _getEstimatedColumnWidth(_PickerColumnType.date));
  }
  }
 

diff --git a/packages/flutter/lib/src/cupertino/form_section.dart b/packages/flutter/lib/src/cupertino/form_section.dart
@@ -210,24 +210,29 @@ class CupertinoFormSection extends StatelessWidget {
  ),
  child: footer!);
 
- return _type == CupertinoListSectionType.base
- ? CupertinoListSection(
- header: headerWidget,
- footer: footerWidget,
- margin: margin,
- backgroundColor: backgroundColor,
- decoration: decoration,
- clipBehavior: clipBehavior,
- hasLeading: false,
- children: children)
- : CupertinoListSection.insetGrouped(
- header: headerWidget,
- footer: footerWidget,
- margin: margin,
- backgroundColor: backgroundColor,
- decoration: decoration,
- clipBehavior: clipBehavior,
- hasLeading: false,
- children: children);
+ switch (_type) {
+ case CupertinoListSectionType.base:
+ return CupertinoListSection(
+ header: headerWidget,
+ footer: footerWidget,
+ margin: margin,
+ backgroundColor: backgroundColor,
+ decoration: decoration,
+ clipBehavior: clipBehavior,
+ hasLeading: false,
+ children: children,
+ );
+ case CupertinoListSectionType.insetGrouped:
+ return CupertinoListSection.insetGrouped(
+ header: headerWidget,
+ footer: footerWidget,
+ margin: margin,
+ backgroundColor: backgroundColor,
+ decoration: decoration,
+ clipBehavior: clipBehavior,
+ hasLeading: false,
+ children: children,
+ );
+ }
  }
 }
diff --git a/packages/flutter/lib/src/gestures/arena.dart b/packages/flutter/lib/src/gestures/arena.dart
@@ -222,22 +222,23 @@ class GestureArenaManager {
  if (state == null) {
  return; // This arena has already resolved.
  }
- assert(_debugLogDiagnostic(pointer, '${ disposition == GestureDisposition.accepted ? "Accepting" : "Rejecting" }: $member'));
  assert(state.members.contains(member));
- if (disposition == GestureDisposition.rejected) {
- state.members.remove(member);
- member.rejectGesture(pointer);
- if (!state.isOpen) {
- _tryToResolveArena(pointer, state);
- }
- } else {
- assert(disposition == GestureDisposition.accepted);
- if (state.isOpen) {
- state.eagerWinner ??= member;
- } else {
- assert(_debugLogDiagnostic(pointer, 'Self-declared winner: $member'));
- _resolveInFavorOf(pointer, state, member);
- }
+ switch (disposition) {
+ case GestureDisposition.accepted:
+ assert(_debugLogDiagnostic(pointer, 'Accepting: $member'));
+ if (state.isOpen) {
+ state.eagerWinner ??= member;
+ } else {
+ assert(_debugLogDiagnostic(pointer, 'Self-declared winner: $member'));
+ _resolveInFavorOf(pointer, state, member);
+ }
+ case GestureDisposition.rejected:
+ assert(_debugLogDiagnostic(pointer, 'Rejecting: $member'));
+ state.members.remove(member);
+ member.rejectGesture(pointer);
+ if (!state.isOpen) {
+ _tryToResolveArena(pointer, state);
+ }
  }
  }
 

diff --git a/packages/flutter/lib/src/gestures/monodrag.dart b/packages/flutter/lib/src/gestures/monodrag.dart
@@ -349,17 +349,20 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
 
  void _addPointer(PointerEvent event) {
  _velocityTrackers[event.pointer] = velocityTrackerBuilder(event);
- if (_state == _DragState.ready) {
- _state = _DragState.possible;
- _initialPosition = OffsetPair(global: event.position, local: event.localPosition);
- _finalPosition = _initialPosition;
- _pendingDragOffset = OffsetPair.zero;
- _globalDistanceMoved = 0.0;
- _lastPendingEventTimestamp = event.timeStamp;
- _lastTransform = event.transform;
- _checkDown();
- } else if (_state == _DragState.accepted) {
- resolve(GestureDisposition.accepted);
+ switch (_state) {
+ case _DragState.ready:
+ _state = _DragState.possible;
+ _initialPosition = OffsetPair(global: event.position, local: event.localPosition);
+ _finalPosition = _initialPosition;
+ _pendingDragOffset = OffsetPair.zero;
+ _globalDistanceMoved = 0.0;
+ _lastPendingEventTimestamp = event.timeStamp;
+ _lastTransform = event.transform;
+ _checkDown();
+ case _DragState.possible:
+ break;
+ case _DragState.accepted:
+ resolve(GestureDisposition.accepted);
  }
  }
 
@@ -421,36 +424,37 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
  final Offset position = (event is PointerMoveEvent) ? event.position : (event.position + (event as PointerPanZoomUpdateEvent).pan);
  final Offset localPosition = (event is PointerMoveEvent) ? event.localPosition : (event.localPosition + (event as PointerPanZoomUpdateEvent).localPan);
  _finalPosition = OffsetPair(local: localPosition, global: position);
- if (_state == _DragState.accepted) {
- _checkUpdate(
- sourceTimeStamp: event.timeStamp,
- delta: _getDeltaForDetails(localDelta),
- primaryDelta: _getPrimaryValueFromOffset(localDelta),
- globalPosition: position,
- localPosition: localPosition,
- );
- } else {
- _pendingDragOffset += OffsetPair(local: localDelta, global: delta);
- _lastPendingEventTimestamp = event.timeStamp;
- _lastTransform = event.transform;
- final Offset movedLocally = _getDeltaForDetails(localDelta);
- final Matrix4? localToGlobalTransform = event.transform == null ? null : Matrix4.tryInvert(event.transform!);
- _globalDistanceMoved += PointerEvent.transformDeltaViaPositions(
- transform: localToGlobalTransform,
- untransformedDelta: movedLocally,
- untransformedEndPosition: localPosition
- ).distance * (_getPrimaryValueFromOffset(movedLocally) ?? 1).sign;
- if (_hasSufficientGlobalDistanceToAccept(event.kind, gestureSettings?.touchSlop)) {
- _hasDragThresholdBeenMet = true;
- if (_acceptedActivePointers.contains(event.pointer)) {
- _checkDrag(event.pointer);
- } else {
- resolve(GestureDisposition.accepted);
+ switch (_state) {
+ case _DragState.ready || _DragState.possible:
+ _pendingDragOffset += OffsetPair(local: localDelta, global: delta);
+ _lastPendingEventTimestamp = event.timeStamp;
+ _lastTransform = event.transform;
+ final Offset movedLocally = _getDeltaForDetails(localDelta);
+ final Matrix4? localToGlobalTransform = event.transform == null ? null : Matrix4.tryInvert(event.transform!);
+ _globalDistanceMoved += PointerEvent.transformDeltaViaPositions(
+ transform: localToGlobalTransform,
+ untransformedDelta: movedLocally,
+ untransformedEndPosition: localPosition
+ ).distance * (_getPrimaryValueFromOffset(movedLocally) ?? 1).sign;
+ if (_hasSufficientGlobalDistanceToAccept(event.kind, gestureSettings?.touchSlop)) {
+ _hasDragThresholdBeenMet = true;
+ if (_acceptedActivePointers.contains(event.pointer)) {
+ _checkDrag(event.pointer);
+ } else {
+ resolve(GestureDisposition.accepted);
+ }
  }
- }
+ case _DragState.accepted:
+ _checkUpdate(
+ sourceTimeStamp: event.timeStamp,
+ delta: _getDeltaForDetails(localDelta),
+ primaryDelta: _getPrimaryValueFromOffset(localDelta),
+ globalPosition: position,
+ localPosition: localPosition,
+ );
  }
  }
- if (event is PointerUpEvent || event is PointerCancelEvent || event is PointerPanZoomEndEvent) {
+ if (event case PointerUpEvent() || PointerCancelEvent() || PointerPanZoomEndEvent()) {
  _giveUpPointer(event.pointer);
  }
  }

diff --git a/packages/flutter/lib/src/material/about.dart b/packages/flutter/lib/src/material/about.dart
@@ -1152,10 +1152,11 @@ class _MasterDetailFlowState extends State<_MasterDetailFlow> implements _PageOp
  @override
  void openDetailPage(Object arguments) {
  _cachedDetailArguments = arguments;
- if (_builtLayout == _LayoutMode.nested) {
- _navigatorKey.currentState!.pushNamed(_navDetail, arguments: arguments);
- } else {
- focus = _Focus.detail;
+ switch (_builtLayout) {
+ case _LayoutMode.nested:
+ _navigatorKey.currentState!.pushNamed(_navDetail, arguments: arguments);
+ case _LayoutMode.lateral || null:
+ focus = _Focus.detail;
  }
  }
 

diff --git a/packages/flutter/lib/src/material/toggle_buttons.dart b/packages/flutter/lib/src/material/toggle_buttons.dart
@@ -455,19 +455,35 @@ class ToggleButtons extends StatelessWidget {
  // Determines if this is the first child that is being laid out
  // by the render object, _not_ the order of the children in its list.
  bool _isFirstButton(int index, int length, TextDirection textDirection) {
- return index == 0 && ((direction == Axis.horizontal && textDirection == TextDirection.ltr) ||
- (direction == Axis.vertical && verticalDirection == VerticalDirection.down))
- || index == length - 1 && ((direction == Axis.horizontal && textDirection == TextDirection.rtl) ||
- (direction == Axis.vertical && verticalDirection == VerticalDirection.up));
+ switch (direction) {
+ case Axis.horizontal:
+ return switch (textDirection) {
+ TextDirection.rtl => index == length - 1,
+ TextDirection.ltr => index == 0,
+ };
+ case Axis.vertical:
+ return switch (verticalDirection) {
+ VerticalDirection.up => index == length - 1,
+ VerticalDirection.down => index == 0,
+ };
+ }
  }
 
  // Determines if this is the last child that is being laid out
  // by the render object, _not_ the order of the children in its list.
  bool _isLastButton(int index, int length, TextDirection textDirection) {
- return index == length - 1 && ((direction == Axis.horizontal && textDirection == TextDirection.ltr) ||
- (direction == Axis.vertical && verticalDirection == VerticalDirection.down))
- || index == 0 && ((direction == Axis.horizontal && textDirection == TextDirection.rtl) ||
- (direction == Axis.vertical && verticalDirection == VerticalDirection.up));
+ switch (direction) {
+ case Axis.horizontal:
+ return switch (textDirection) {
+ TextDirection.rtl => index == 0,
+ TextDirection.ltr => index == length - 1,
+ };
+ case Axis.vertical:
+ return switch (verticalDirection) {
+ VerticalDirection.up => index == 0,
+ VerticalDirection.down => index == length - 1,
+ };
+ }
  }
 
  BorderRadius _getEdgeBorderRadius(