Simplify Flutter support to a single instance.

Change-Id: I90813c4e01694510971c4ce9cf96a4a3380a2923
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153952
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analysis_server/lib/src/computer/computer_outline.dart

@@ -16,10 +16,8 @@ import 'package:analyzer_plugin/protocol/protocol_common.dart';
 class DartUnitOutlineComputer {
   final ResolvedUnitResult resolvedUnit;
   final bool withBasicFlutter;
-  final Flutter flutter;
 
-  DartUnitOutlineComputer(this.resolvedUnit, {this.withBasicFlutter = false})
-      : flutter = Flutter.of(resolvedUnit);
+  DartUnitOutlineComputer(this.resolvedUnit, {this.withBasicFlutter = false});
 
   /// Returns the computed outline, not `null`.
   Outline compute() {
@@ -409,6 +407,8 @@ class _FunctionBodyOutlinesVisitor extends RecursiveAstVisitor<void> {
 
   _FunctionBodyOutlinesVisitor(this.outlineComputer, this.contents);
 
+  Flutter get _flutter => Flutter.instance;
+
   /// Return `true` if the given [element] is the method 'group' defined in the
   /// test package.
   bool isGroup(engine.ExecutableElement element) {
@@ -438,13 +438,12 @@ class _FunctionBodyOutlinesVisitor extends RecursiveAstVisitor<void> {
 
   @override
   void visitInstanceCreationExpression(InstanceCreationExpression node) {
-    if (outlineComputer.withBasicFlutter &&
-        outlineComputer.flutter.isWidgetCreation(node)) {
+    if (outlineComputer.withBasicFlutter && _flutter.isWidgetCreation(node)) {
       var children = <Outline>[];
       node.argumentList
           .accept(_FunctionBodyOutlinesVisitor(outlineComputer, children));
 
-      var text = outlineComputer.flutter.getWidgetPresentationText(node);
+      var text = _flutter.getWidgetPresentationText(node);
       var element = Element(ElementKind.CONSTRUCTOR_INVOCATION, text, 0,
           location: outlineComputer._getLocationOffsetLength(node.offset, 0));
 

pkg/analysis_server/lib/src/flutter/flutter_outline_computer.dart

@@ -13,20 +13,19 @@ import 'package:analyzer/dart/element/element.dart';
 /// Computer for Flutter specific outlines.
 class FlutterOutlineComputer {
   final ResolvedUnitResult resolvedUnit;
-  Flutter flutter;
 
   final List<protocol.FlutterOutline> _depthFirstOrder = [];
 
   FlutterOutlineComputer(this.resolvedUnit);
 
+  Flutter get _flutter => Flutter.instance;
+
   protocol.FlutterOutline compute() {
     var dartOutline = DartUnitOutlineComputer(
       resolvedUnit,
       withBasicFlutter: false,
     ).compute();
 
-    flutter = Flutter.of(resolvedUnit);
-
     // Convert Dart outlines into Flutter outlines.
     var flutterDartOutline = _convert(dartOutline);
 
@@ -131,7 +130,7 @@ class FlutterOutlineComputer {
   /// a widget reference outline item.
   protocol.FlutterOutline _createOutline(Expression node, bool withGeneric) {
     var type = node.staticType;
-    if (!flutter.isWidgetType(type)) {
+    if (!_flutter.isWidgetType(type)) {
       return null;
     }
     var className = type.element.displayName;
@@ -140,9 +139,9 @@ class FlutterOutlineComputer {
       var attributes = <protocol.FlutterOutlineAttribute>[];
       var children = <protocol.FlutterOutline>[];
       for (var argument in node.argumentList.arguments) {
-        var isWidgetArgument = flutter.isWidgetType(argument.staticType);
+        var isWidgetArgument = _flutter.isWidgetType(argument.staticType);
         var isWidgetListArgument =
-            flutter.isListOfWidgetsType(argument.staticType);
+            _flutter.isListOfWidgetsType(argument.staticType);
 
         String parentAssociationLabel;
         Expression childrenExpression;

pkg/analysis_server/lib/src/services/completion/dart/arglist_contributor.dart

@@ -163,7 +163,7 @@ class ArgListContributor extends DartCompletionContributor {
   }
 
   bool _isInFlutterCreation() {
-    var flutter = Flutter.of(request.result);
+    var flutter = Flutter.instance;
     var containingNode = request.target?.containingNode;
     var newExpr = containingNode != null
         ? flutter.identifyNewExpression(containingNode.parent)

pkg/analysis_server/lib/src/services/completion/dart/suggestion_builder.dart

@@ -164,17 +164,12 @@ class SuggestionBuilder {
   /// computed. In the latter case, [_hasContainingMemberName] will be `false`.
   String _cachedContainingMemberName;
 
-  /// The cached instance of the flutter utilities, or `null` if it hasn't been
-  /// created yet.
-  Flutter _flutter;
-
   /// Initialize a newly created suggestion builder to build suggestions for the
   /// given [request].
   SuggestionBuilder(this.request, {this.listener});
 
-  /// Return an object that can answer questions about Flutter code based on the
-  /// flavor of Flutter being used.
-  Flutter get flutter => _flutter ??= Flutter.of(request.result);
+  /// Return an object that can answer questions about Flutter code.
+  Flutter get flutter => Flutter.instance;
 
   /// Return an iterable that can be used to access the completion suggestions
   /// that have been built.
@@ -803,8 +798,7 @@ class SuggestionBuilder {
     // todo (pq): revisit this special casing; likely it can be generalized away
     var element = parameter.enclosingElement;
     if (element is ConstructorElement) {
-      var flutter = Flutter.of(request.result);
-      if (flutter.isWidget(element.enclosingElement)) {
+      if (Flutter.instance.isWidget(element.enclosingElement)) {
         var defaultValue = getDefaultStringParameterValue(parameter);
         // TODO(devoncarew): Should we remove the check here? We would then
         // suggest values for param types like closures.

pkg/analysis_server/lib/src/services/correction/base_processor.dart

@@ -23,7 +23,6 @@ abstract class BaseProcessor {
   final String file;
 
   final TypeProvider typeProvider;
-  final Flutter flutter;
 
   final AnalysisSession session;
   final AnalysisSessionHelper sessionHelper;
@@ -38,13 +37,14 @@ abstract class BaseProcessor {
     @required this.resolvedResult,
     @required this.workspace,
   })  : file = resolvedResult.path,
-        flutter = Flutter.of(resolvedResult),
         session = resolvedResult.session,
         sessionHelper = AnalysisSessionHelper(resolvedResult.session),
         typeProvider = resolvedResult.typeProvider,
         selectionEnd = (selectionOffset ?? 0) + (selectionLength ?? 0),
         utils = CorrectionUtils(resolvedResult);
 
+  Flutter get flutter => Flutter.instance;
+
   @protected
   bool setupCompute() {
     final locator = NodeLocator(selectionOffset, selectionEnd);

pkg/analysis_server/lib/src/services/correction/dart/abstract_producer.dart

@@ -252,7 +252,6 @@ class CorrectionProducerContext {
   final String file;
 
   final TypeProvider typeProvider;
-  final Flutter flutter;
 
   final AnalysisSession session;
   final AnalysisSessionHelper sessionHelper;
@@ -272,7 +271,6 @@ class CorrectionProducerContext {
     this.selectionOffset = -1,
     this.selectionLength = 0,
   })  : file = resolvedResult.path,
-        flutter = Flutter.of(resolvedResult),
         session = resolvedResult.session,
         sessionHelper = AnalysisSessionHelper(resolvedResult.session),
         typeProvider = resolvedResult.typeProvider,
@@ -344,7 +342,7 @@ abstract class _AbstractCorrectionProducer {
 
   String get file => _context.file;
 
-  Flutter get flutter => _context.flutter;
+  Flutter get flutter => Flutter.instance;
 
   /// Return the library element for the library in which a correction is being
   /// produced.

pkg/analysis_server/lib/src/services/flutter/widget_descriptions.dart

@@ -131,9 +131,6 @@ class _WidgetDescriptionComputer {
   /// The offset of the widget expression.
   final int widgetOffset;
 
-  /// The instance of [Flutter] support.
-  final Flutter flutter;
-
   ClassElement _classAlignment;
   ClassElement _classAlignmentDirectional;
   ClassElement _classContainer;
@@ -143,11 +140,13 @@ class _WidgetDescriptionComputer {
     this.classRegistry,
     this.resolvedUnit,
     this.widgetOffset,
-  ) : flutter = Flutter.of(resolvedUnit);
+  );
+
+  Flutter get _flutter => Flutter.instance;
 
   Future<_WidgetDescription> compute() async {
     var node = NodeLocator2(widgetOffset).searchWithin(resolvedUnit.unit);
-    var instanceCreation = flutter.identifyNewExpression(node);
+    var instanceCreation = _flutter.identifyNewExpression(node);
     if (instanceCreation == null) {
       return null;
     }
@@ -173,7 +172,7 @@ class _WidgetDescriptionComputer {
     List<PropertyDescription> properties,
     InstanceCreationExpression widgetCreation,
   ) {
-    if (!flutter.isWidgetCreation(widgetCreation)) {
+    if (!_flutter.isWidgetCreation(widgetCreation)) {
       return;
     }
 
@@ -190,7 +189,7 @@ class _WidgetDescriptionComputer {
     }
 
     PropertyDescription containerProperty;
-    if (flutter.isExactlyContainerCreation(parentCreation)) {
+    if (_flutter.isExactlyContainerCreation(parentCreation)) {
       containerProperty = PropertyDescription(
         resolvedUnit: resolvedUnit,
         instanceCreation: parentCreation,
@@ -236,17 +235,17 @@ class _WidgetDescriptionComputer {
         classDescription: containerDescription,
       );
 
-      if (flutter.isExactlyAlignCreation(parentCreation) &&
-          flutter.findNamedArgument(parentCreation, 'widthFactor') == null &&
-          flutter.findNamedArgument(parentCreation, 'heightFactor') == null) {
+      if (_flutter.isExactlyAlignCreation(parentCreation) &&
+          _flutter.findNamedArgument(parentCreation, 'widthFactor') == null &&
+          _flutter.findNamedArgument(parentCreation, 'heightFactor') == null) {
         _replaceNestedContainerProperty(
           containerProperty,
           parentCreation,
           'alignment',
         );
       }
 
-      if (flutter.isExactlyPaddingCreation(parentCreation)) {
+      if (_flutter.isExactlyPaddingCreation(parentCreation)) {
         _replaceNestedContainerProperty(
           containerProperty,
           parentCreation,
@@ -347,7 +346,7 @@ class _WidgetDescriptionComputer {
     var propertyDescription = PropertyDescription(
       parent: parent,
       resolvedUnit: resolvedUnit,
-      flutter: flutter,
+      flutter: _flutter,
       classDescription: classDescription,
       instanceCreation: instanceCreation,
       argumentExpression: argumentExpression,
@@ -366,7 +365,7 @@ class _WidgetDescriptionComputer {
     );
     properties.add(propertyDescription);
 
-    if (flutter.isExactEdgeInsetsGeometryType(parameter.type)) {
+    if (_flutter.isExactEdgeInsetsGeometryType(parameter.type)) {
       propertyDescription.addEdgeInsetsNestedProperties(_classEdgeInsets);
     } else if (valueExpression is InstanceCreationExpression) {
       var type = valueExpression.staticType;
@@ -414,19 +413,19 @@ class _WidgetDescriptionComputer {
   Future<void> _fetchClassElements() async {
     var sessionHelper = AnalysisSessionHelper(resolvedUnit.session);
     _classAlignment = await sessionHelper.getClass(
-      flutter.widgetsUri,
+      _flutter.widgetsUri,
       'Alignment',
     );
     _classAlignmentDirectional = await sessionHelper.getClass(
-      flutter.widgetsUri,
+      _flutter.widgetsUri,
       'AlignmentDirectional',
     );
     _classContainer = await sessionHelper.getClass(
-      flutter.widgetsUri,
+      _flutter.widgetsUri,
       'Container',
     );
     _classEdgeInsets = await sessionHelper.getClass(
-      flutter.widgetsUri,
+      _flutter.widgetsUri,
       'EdgeInsets',
     );
   }
@@ -460,7 +459,7 @@ class _WidgetDescriptionComputer {
           enumItems: _enumItemsForEnum(classElement),
         );
       }
-      if (flutter.isExactAlignmentGeometry(classElement)) {
+      if (_flutter.isExactAlignmentGeometry(classElement)) {
         var items = <protocol.FlutterWidgetPropertyValueEnumItem>[];
         items.addAll(
           _enumItemsForStaticFields(_classAlignment),
@@ -484,7 +483,7 @@ class _WidgetDescriptionComputer {
     InstanceCreationExpression parentCreation,
     String name,
   ) {
-    var argument = flutter.findNamedArgument(parentCreation, name);
+    var argument = _flutter.findNamedArgument(parentCreation, name);
     if (argument != null) {
       var replacements = <PropertyDescription>[];
       _addProperty(
@@ -536,8 +535,8 @@ class _WidgetDescriptionComputer {
         if (field is FieldElement && field.isStatic) {
           var enclosingClass = field.enclosingElement as ClassElement;
           if (field.isEnumConstant ||
-              flutter.isExactAlignment(enclosingClass) ||
-              flutter.isExactAlignmentDirectional(enclosingClass)) {
+              _flutter.isExactAlignment(enclosingClass) ||
+              _flutter.isExactAlignmentDirectional(enclosingClass)) {
             return protocol.FlutterWidgetPropertyValue(
               enumValue: _toEnumItem(field),
             );

pkg/analysis_server/lib/src/services/refactoring/extract_widget.dart

@@ -37,7 +37,6 @@ class ExtractWidgetRefactoringImpl extends RefactoringImpl
   final int length;
 
   CorrectionUtils utils;
-  Flutter flutter;
 
   ClassElement classBuildContext;
   ClassElement classKey;
@@ -78,7 +77,6 @@ class ExtractWidgetRefactoringImpl extends RefactoringImpl
       this.searchEngine, this.resolveResult, this.offset, this.length)
       : sessionHelper = AnalysisSessionHelper(resolveResult.session) {
     utils = CorrectionUtils(resolveResult);
-    flutter = Flutter.of(resolveResult);
   }
 
   @override
@@ -90,6 +88,8 @@ class ExtractWidgetRefactoringImpl extends RefactoringImpl
     return resolveResult.unit.featureSet;
   }
 
+  Flutter get _flutter => Flutter.instance;
+
   bool get _isNonNullable => _featureSet.isEnabled(Feature.non_nullable);
 
   @override
@@ -184,8 +184,8 @@ class ExtractWidgetRefactoringImpl extends RefactoringImpl
     _enclosingClassElement = _enclosingClassNode?.declaredElement;
 
     // new MyWidget(...)
-    var newExpression = flutter.identifyNewExpression(node);
-    if (flutter.isWidgetCreation(newExpression)) {
+    var newExpression = _flutter.identifyNewExpression(node);
+    if (_flutter.isWidgetCreation(newExpression)) {
       _expression = newExpression;
       return RefactoringStatus();
     }
@@ -203,7 +203,7 @@ class ExtractWidgetRefactoringImpl extends RefactoringImpl
       if (statements.isNotEmpty) {
         var lastStatement = statements.last;
         if (lastStatement is ReturnStatement &&
-            flutter.isWidgetExpression(lastStatement.expression)) {
+            _flutter.isWidgetExpression(lastStatement.expression)) {
           _statements = statements;
           _statementsRange = range.startEnd(statements.first, statements.last);
           return RefactoringStatus();
@@ -221,7 +221,7 @@ class ExtractWidgetRefactoringImpl extends RefactoringImpl
       }
       if (node is MethodDeclaration) {
         var returnType = node.returnType?.type;
-        if (flutter.isWidgetType(returnType) && node.body != null) {
+        if (_flutter.isWidgetType(returnType) && node.body != null) {
           _method = node;
           return RefactoringStatus();
         }
@@ -238,10 +238,10 @@ class ExtractWidgetRefactoringImpl extends RefactoringImpl
     var result = RefactoringStatus();
 
     Future<ClassElement> getClass(String name) async {
-      var element = await sessionHelper.getClass(flutter.widgetsUri, name);
+      var element = await sessionHelper.getClass(_flutter.widgetsUri, name);
       if (element == null) {
         result.addFatalError(
-          "Unable to find '$name' in ${flutter.widgetsUri}",
+          "Unable to find '$name' in ${_flutter.widgetsUri}",
         );
       }
       return element;

pkg/analysis_server/lib/src/services/refactoring/rename_unit_member.dart

@@ -141,8 +141,7 @@ class RenameUnitMemberRefactoringImpl extends RenameRefactoringImpl {
   }
 
   void _findFlutterStateClass() {
-    var flutter = Flutter.of(resolvedUnit);
-    if (flutter.isStatefulWidgetDeclaration(element)) {
+    if (Flutter.instance.isStatefulWidgetDeclaration(element)) {
       var oldStateName = oldName + 'State';
       _flutterWidgetState = element.library.getType(oldStateName) ??
           element.library.getType('_' + oldStateName);