Completion boilerplate for Flutter cons children (flutter-intellij#463)

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

Index: pkg/analysis_server/lib/src/services/completion/dart/utilities.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/utilities.dart b/pkg/analysis_server/lib/src/services/completion/dart/utilities.dart
index 80002537ba2f696601afd7b98ca51cd537c446f8..6d8ce556bafc0b38ca84bb683a8133456d88ebee 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/utilities.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/utilities.dart
@@ -7,13 +7,16 @@
  */
 import 'package:analysis_server/plugin/protocol/protocol.dart' as protocol
     show Element, ElementKind;
+import 'package:analysis_server/src/ide_options.dart';
 import 'package:analysis_server/src/protocol_server.dart'
     show CompletionSuggestion, CompletionSuggestionKind, Location;
 import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
+import 'package:analysis_server/src/services/correction/flutter_util.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/ast/token.dart';
 import 'package:analyzer/src/generated/source.dart';
 
@@ -35,8 +38,10 @@ final TypeName NO_RETURN_TYPE = astFactory.typeName(
  */
 void addDefaultArgDetails(
     CompletionSuggestion suggestion,
+    Element element,
     Iterable<ParameterElement> requiredParams,
-    Iterable<ParameterElement> namedParams) {
+    Iterable<ParameterElement> namedParams,
+    IdeOptions options) {
   StringBuffer sb = new StringBuffer();
   List<int> ranges = <int>[];
 
@@ -66,6 +71,32 @@ void addDefaultArgDetails(
     }
   }
 
+  //TODO(pq): generalize and unify with _getDefaultValue
+  if (options?.generateFlutterWidgetChildrenBoilerPlate == true) {

[Brian Wilkerson, 2017/03/22 22:05:46]

I think I'd just make it mandatory to pass in a non-null options object. ymmv.

+    if (element is ConstructorElement) {
+      ConstructorElement constructorElement = element;
+      ClassElement classElement = constructorElement.enclosingElement;
+      if (isFlutterWidget(classElement)) {
+        for (ParameterElement param in constructorElement.parameters) {
+          if (param.name == 'children') {
+            DartType type = param.type;
+            if (type is InterfaceType && _isDartList(type)) {
+              InterfaceType interfaceType = type;
+              List<DartType> typeArguments = interfaceType.typeArguments;
+              if (typeArguments.length == 1) {
+                if (sb.isNotEmpty) {
+                  sb.write(', ');
+                }
+                offset = sb.length;
+                sb.write('children: <${typeArguments.first.name}>[]');
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+
   suggestion.defaultArgumentListString = sb.isNotEmpty ? sb.toString() : null;
   suggestion.defaultArgumentListTextRanges = ranges.isNotEmpty ? ranges : null;
 }
@@ -199,3 +230,11 @@ String nameForType(TypeAnnotation type) {
 }
 
 String _getDefaultValue(ParameterElement param) => 'null';
+
+bool _isDartList(DartType type) {
+  ClassElement element = type.element;
+  if (element != null) {
+    return element.name == "List" && element.library.isDartCore;
+  }
+  return false;
+}