Quick Assist for creating a constructor for selected final fields.

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

Index: pkg/analysis_server/lib/src/services/correction/assist_internal.dart
diff --git a/pkg/analysis_server/lib/src/services/correction/assist_internal.dart b/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
index 525a198d0775746ccd58a30bee4c5079c91d9c15..cb69ae74d460a4c50cbc1aec91a4482b997d8e1f 100644
--- a/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
@@ -84,6 +84,7 @@ class AssistProcessor {
     _addProposal_convertToIsNot_onIs();
     _addProposal_convertToIsNot_onNot();
     _addProposal_convertToIsNotEmpty();
+    _addProposal_createFieldFieldsConstructor();
     _addProposal_exchangeOperands();
     _addProposal_importAddShow();
     _addProposal_introduceLocalTestedType();
@@ -215,6 +216,44 @@ class AssistProcessor {
     _addAssist(AssistKind.ADD_TYPE_ANNOTATION, []);
   }
 
+  void _addProposal_addTypeAnnotation_SimpleFormalParameter() {
+    AstNode node = this.node;
+    // should be the name of a simple parameter
+    if (node is! SimpleIdentifier || node.parent is! SimpleFormalParameter) {
+      _coverageMarker();
+      return;
+    }
+    SimpleIdentifier name = node;
+    SimpleFormalParameter parameter = node.parent;
+    // the parameter should not have a type
+    if (parameter.type != null) {
+      _coverageMarker();
+      return;
+    }
+    // prepare propagated type
+    DartType type = name.propagatedType;
+    // TODO(scheglov) If the parameter is in a method declaration, and if the
+    // method overrides a method that has a type for the corresponding
+    // parameter, it would be nice to copy down the type from the overridden
+    // method.
+    if (type is! InterfaceType) {
+      _coverageMarker();
+      return;
+    }
+    // prepare type source
+    String typeSource;
+    {
+      _configureTargetLocation(node);
+      Set<LibraryElement> librariesToImport = new Set<LibraryElement>();
+      typeSource = utils.getTypeSource(type, librariesToImport);
+      addLibraryImports(change, unitLibraryElement, librariesToImport);
+    }
+    // add edit
+    _addInsertEdit(name.offset, '$typeSource ');
+    // add proposal
+    _addAssist(AssistKind.ADD_TYPE_ANNOTATION, []);
+  }
+
   void _addProposal_addTypeAnnotation_VariableDeclaration() {
     AstNode node = this.node;
     // check if "var v = 42;^"
@@ -270,44 +309,6 @@ class AssistProcessor {
     _addAssist(AssistKind.ADD_TYPE_ANNOTATION, []);
   }
 
-  void _addProposal_addTypeAnnotation_SimpleFormalParameter() {
-    AstNode node = this.node;
-    // should be the name of a simple parameter
-    if (node is! SimpleIdentifier || node.parent is! SimpleFormalParameter) {
-      _coverageMarker();
-      return;
-    }
-    SimpleIdentifier name = node;
-    SimpleFormalParameter parameter = node.parent;
-    // the parameter should not have a type
-    if (parameter.type != null) {
-      _coverageMarker();
-      return;
-    }
-    // prepare propagated type
-    DartType type = name.propagatedType;
-    // TODO(scheglov) If the parameter is in a method declaration, and if the
-    // method overrides a method that has a type for the corresponding
-    // parameter, it would be nice to copy down the type from the overridden
-    // method.
-    if (type is! InterfaceType) {
-      _coverageMarker();
-      return;
-    }
-    // prepare type source
-    String typeSource;
-    {
-      _configureTargetLocation(node);
-      Set<LibraryElement> librariesToImport = new Set<LibraryElement>();
-      typeSource = utils.getTypeSource(type, librariesToImport);
-      addLibraryImports(change, unitLibraryElement, librariesToImport);
-    }
-    // add edit
-    _addInsertEdit(name.offset, '$typeSource ');
-    // add proposal
-    _addAssist(AssistKind.ADD_TYPE_ANNOTATION, []);
-  }
-
   void _addProposal_assignToLocalVariable() {
     // prepare enclosing ExpressionStatement
     Statement statement = node.getAncestor((node) => node is Statement);
@@ -578,6 +579,55 @@ class AssistProcessor {
     _addAssist(AssistKind.CONVERT_INTO_IS_NOT_EMPTY, []);
   }
 
+  void _addProposal_createFieldFieldsConstructor() {
+    // prepare enclosing ClassDeclaration
+    if (node is! ClassDeclaration) {
+      _coverageMarker();
+      return;
+    }
+    ClassDeclaration classDeclaration = node;
+    // prepare names of final fields covered be the selection
+    List<String> fieldNames = <String>[];
+    for (ClassMember member in classDeclaration.members) {
+      if (member is FieldDeclaration) {
+        if (member.end < selectionOffset) {
+          _coverageMarker();
+          continue;
+        }
+        if (member.offset > selectionOffset + selectionLength) {
+          _coverageMarker();
+          continue;
+        }
+        VariableDeclarationList variableList = member.fields;
+        if (variableList.isFinal) {
+          List<VariableDeclaration> variables = variableList.variables;
+          fieldNames.addAll(variables.map((v) => v.name.name));
+        }
+      }
+    }
+    // add proposal
+    if (fieldNames.isNotEmpty) {
+      ConstructorLocation targetLocation =
+          utils.findNewConstructorLocation(classDeclaration);
+      // build method source
+      SourceBuilder sb = new SourceBuilder(file, targetLocation.offset);
+      {
+        String indent = '  ';
+        sb.append(targetLocation.prefix);
+        sb.append(indent);
+        sb.append(classDeclaration.name.name);
+        sb.append('(');
+        sb.append(fieldNames.map((name) => 'this.$name').join(', '));
+        sb.append(');');
+        sb.append(targetLocation.suffix);
+      }
+      // insert source
+      _insertBuilder(sb);
+      // add proposal
+      _addAssist(AssistKind.CREATE_FINAL_FIELD_CONSTRUCTOR, []);
+    }
+  }
+
   void _addProposal_exchangeOperands() {
     // check that user invokes quick assist on binary expression
     if (node is! BinaryExpression) {