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

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

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * A collection of utility methods used by completion contributors.
  */
 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';
 
 /**
  * The name of the type `dynamic`;
  */
 const DYNAMIC = 'dynamic';
 
 /**
  * A marker used in place of `null` when a function has no return type.
  */
 final TypeName NO_RETURN_TYPE = astFactory.typeName(
     astFactory.simpleIdentifier(new StringToken(TokenType.IDENTIFIER, '', 0)),
     null);
 
 /**
  * Add default argument list text and ranges based on the given [requiredParams]
  * and [namedParams].
  */
 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>[];
 
   int offset;
 
   for (ParameterElement param in requiredParams) {
     if (sb.isNotEmpty) {
       sb.write(', ');
     }
     offset = sb.length;
     String name = param.name;
     sb.write(name);
     ranges.addAll([offset, name.length]);
   }
 
   for (ParameterElement param in namedParams) {
     if (param.isRequired) {
       if (sb.isNotEmpty) {
         sb.write(', ');
       }
       String name = param.name;
       sb.write('$name: ');
       offset = sb.length;
       String defaultValue = _getDefaultValue(param);
       sb.write(defaultValue);
       ranges.addAll([offset, defaultValue.length]);
     }
   }
 
+  //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;
 }
 
 /**
  * Create a new protocol Element for inclusion in a completion suggestion.
  */
 protocol.Element createLocalElement(
     Source source, protocol.ElementKind kind, SimpleIdentifier id,
     {String parameters,
@@ skipping 113 matching lines @@
       //TODO (danrubel) include type arguments
     }
     return name;
   } else if (type is GenericFunctionType) {
     // TODO(brianwilkerson) Implement this.
   }
   return DYNAMIC;
 }
 
 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;
+}