add code completion cache

pkg/analysis_server/lib/src/domain_completion.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 domain.completion;
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/completion/completion_manager.dart';
 
+export 'package:analysis_server/src/services/completion/completion_manager.dart'
+    show CompletionPerformance, OperationPerformance;
+
 /**
  * Instances of the class [CompletionDomainHandler] implement a [RequestHandler]
  * that handles requests in the search domain.
  */
 class CompletionDomainHandler implements RequestHandler {
   /**
    * The analysis server that is using this handler to process requests.
    */
   final AnalysisServer server;
 
   /**
    * The next completion response id.
    */
   int _nextCompletionId = 0;
 
   /**
+   * Cached information from a prior completion operation.
+   * The type of cached information depends upon the completion operation.
+   */
+  // TODO (danrubel) clear cache if either source or context changes
+  CompletionCache _cache;
+
+  /**
    * Code completion peformance for the last completion operation.
    */
   CompletionPerformance performance;
 
   /**
    * Initialize a new request handler for the given [server].
    */
   CompletionDomainHandler(this.server);
 
   @override
@@ skipping 12 matching lines @@
   /**
    * Process a `completion.getSuggestions` request.
    */
   Response processRequest(Request request) {
     performance = new CompletionPerformance();
     // extract params
     CompletionGetSuggestionsParams params =
         new CompletionGetSuggestionsParams.fromRequest(request);
     // schedule completion analysis
     String completionId = (_nextCompletionId++).toString();
-    CompletionManager.create(
+    CompletionManager manager = new CompletionManager.create(
         server.getAnalysisContext(params.file),
         server.getSource(params.file),
         params.offset,
         server.searchEngine,
-        performance).results().listen((CompletionResult result) {
+        _cache,
+        performance);
+    manager.results().listen((CompletionResult result) {
       sendCompletionNotification(
           completionId,
           result.replacementOffset,
           result.replacementLength,
           result.suggestions,
           result.last);
       if (result.last) {
         performance.complete();
+        _cache = manager.completionCache;
       }
     });
     // initial response without results
     return new CompletionGetSuggestionsResult(
         completionId).toResponse(request.id);
   }
 
   /**
    * Send completion notification results.
    */
   void sendCompletionNotification(String completionId, int replacementOffset,
       int replacementLength, Iterable<CompletionSuggestion> results, bool isLast) {
     server.sendNotification(
         new CompletionResultsParams(
             completionId,
             replacementOffset,
             replacementLength,
             results,
             isLast).toNotification());
   }
 }