Include required parameter names when completing a method call.

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

 // Copyright (c) 2014, 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.
 
 library services.completion.suggestion.builder;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol_server.dart' as protocol;
 import 'package:analysis_server/src/protocol_server.dart' hide Element,
     ElementKind;
 import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
+import 'package:analyzer/src/generated/utilities_dart.dart';
 
 /**
  * Create a suggestion based upon the given imported element.
  */
 CompletionSuggestion createElementSuggestion(Element element,
     {CompletionRelevance relevance: CompletionRelevance.DEFAULT}) {
   String completion = element.displayName;
   CompletionSuggestion suggestion = new CompletionSuggestion(
       CompletionSuggestionKind.INVOCATION,
       element.isDeprecated ? CompletionRelevance.LOW : relevance,
@@ skipping 351 matching lines @@
     }
     if (enclosingElement != null) {
       suggestion.declaringType = enclosingElement.displayName;
     }
     if (type != null) {
       String typeName = type.displayName;
       if (typeName != null && typeName.length > 0 && typeName != 'dynamic') {
         suggestion.returnType = typeName;
       }
     }
+    if (element is ExecutableElement && element is! PropertyAccessorElement) {
+      suggestion.parameterNames = element.parameters.map(
+          (ParameterElement parameter) => parameter.name).toList();
+      suggestion.parameterTypes = element.parameters.map(
+          (ParameterElement parameter) => parameter.type.displayName).toList();

[danrubel, 2015/01/06 23:49:36]

Can parameter.type ever be null?

[Paul Berry, 2015/01/07 15:39:14]

My belief is that it should never be null, but I will double check with Brian
this morning.

+      suggestion.requiredParameterCount = element.parameters.where(
+          (ParameterElement parameter) =>
+              parameter.parameterKind == ParameterKind.REQUIRED).length;
+      suggestion.hasNamedParameters = element.parameters.any(
+          (ParameterElement parameter) => parameter.parameterKind == ParameterKind.NAMED);
+    }
     request.suggestions.add(suggestion);
   }
 }