refactor optype to be computed once per refactoring request

pkg/analysis_server/lib/src/services/completion/local_computer.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.computer.dart.local;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart' as protocol show Element,
     ElementKind;
 import 'package:analysis_server/src/protocol.dart' hide Element, ElementKind;
 import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
 import 'package:analysis_server/src/services/completion/local_declaration_visitor.dart';
-import 'package:analysis_server/src/services/completion/optype_ast_visitor.dart';
+import 'package:analysis_server/src/services/completion/optype.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 
 /**
  * A computer for calculating `completion.getSuggestions` request results
  * for the local library in which the completion is requested.
  */
 class LocalComputer extends DartCompletionComputer {
 
   @override
   bool computeFast(DartCompletionRequest request) {
-
-    // Determine the type of suggestions to be made
-    OpTypeAstVisitor opTypeVisitor = new OpTypeAstVisitor(request.offset);
-    request.node.accept(opTypeVisitor);
-
-    // Build the suggestions
-    if (opTypeVisitor.includeTopLevelSuggestions) {
+    OpType optype = request.optype;
+    if (optype.includeTopLevelSuggestions) {
       _LocalVisitor localVisitor = new _LocalVisitor(request, request.offset);
-      localVisitor.typesOnly = opTypeVisitor.includeOnlyTypeNameSuggestions;
-      localVisitor.excludeVoidReturn =
-          !opTypeVisitor.includeVoidReturnSuggestions;
+      localVisitor.typesOnly = optype.includeOnlyTypeNameSuggestions;
+      localVisitor.excludeVoidReturn = !optype.includeVoidReturnSuggestions;
 
       // Collect suggestions from the specific child [AstNode] that contains
       // the completion offset and all of its parents recursively.
       request.node.accept(localVisitor);
     }
 
     // If the unit is not a part and does not reference any parts
     // then work is complete
     return !request.unit.directives.any(
         (Directive directive) =>
@@ skipping 325 matching lines @@
     if (name == null || name.length <= 0) {
       return DYNAMIC;
     }
     TypeArgumentList typeArgs = type.typeArguments;
     if (typeArgs != null) {
       //TODO (danrubel) include type arguments
     }
     return name;
   }
 }