make completion managers responsible for their own caches

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

Index: pkg/analysis_server/lib/src/services/completion/completion_manager.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/completion_manager.dart b/pkg/analysis_server/lib/src/services/completion/completion_manager.dart
index 10b1486de8bdcdfda2e46e90f88aecb7272e03cb..e60f875be8efd23dcf16129828c69da64042065d 100644
--- a/pkg/analysis_server/lib/src/services/completion/completion_manager.dart
+++ b/pkg/analysis_server/lib/src/services/completion/completion_manager.dart
@@ -37,57 +37,60 @@ abstract class CompletionCache {
 abstract class CompletionManager {
 
   /**
+   * The context in which the completion was computed.
+   */
+  final AnalysisContext context;
+
+  /**
+   * The source in which the completion was computed.
+   */
+  final Source source;
+
+  /**
    * The controller used for returning completion results.
    */
   StreamController<CompletionResult> controller;
 
-  CompletionManager();
+  CompletionManager(this.context, this.source);
 
   /**
    * Create a manager for the given request.
    */
   factory CompletionManager.create(AnalysisContext context, Source source,
-      int offset, SearchEngine searchEngine, CompletionCache cache,
-      CompletionPerformance performance) {
+      SearchEngine searchEngine, CompletionCache cache) {
     if (context != null) {
       if (AnalysisEngine.isDartFileName(source.shortName)) {
         return new DartCompletionManager.create(
             context,
             searchEngine,
             source,
-            offset,
-            cache,
-            performance);
+            cache);
       }
       if (AnalysisEngine.isHtmlFileName(source.shortName)) {
         //TODO (danrubel) implement
 //        return new HtmlCompletionManager(context, searchEngine, source, offset);
       }
     }
-    return new NoOpCompletionManager(source, offset);
+    return new NoOpCompletionManager(source);
   }
 
   /**
-   * Return cached information from the current completion operation
-   * if there is any. Subclasses may override this method.
-   */
-  CompletionCache get completionCache => null;
-
-  /**
-   * Compute completion results and append them to the stream.
+   * Compute completion results for the given reqeust and append them to the stream.
    * Clients should not call this method directly as it is automatically called
    * when a client listens to the stream returned by [results].
    * Subclasses should override this method, append at least one result
    * to the [controller], and close the controller stream once complete.
    */
-  void compute();
+  void compute(CompletionRequest request);
 
   /**
    * Generate a stream of code completion results.
    */
-  Stream<CompletionResult> results() {
+  Stream<CompletionResult> results(CompletionRequest request) {
     controller = new StreamController<CompletionResult>(onListen: () {
-      scheduleMicrotask(compute);
+      scheduleMicrotask(() {
+        compute(request);
+      });
     });
     return controller.stream;
   }
@@ -139,6 +142,23 @@ class CompletionPerformance {
 }
 
 /**
+ * Encapsulates information specific to a particular completion request.
+ */
+class CompletionRequest {
+  /**
+   * The offset within the source at which the completion is requested.
+   */
+  final int offset;
+
+  /**
+   * Performance measurements for this particular request.
+   */
+  final CompletionPerformance performance;
+
+  CompletionRequest(this.offset, this.performance);
+}
+
+/**
  * Code completion result generated by an [CompletionManager].
  */
 class CompletionResult {
@@ -174,14 +194,12 @@ class CompletionResult {
 }
 
 class NoOpCompletionManager extends CompletionManager {
-  final Source source;
-  final int offset;
 
-  NoOpCompletionManager(this.source, this.offset);
+  NoOpCompletionManager(Source source) : super(null, source);
 
   @override
-  void compute() {
-    controller.add(new CompletionResult(offset, 0, [], true));
+  void compute(CompletionRequest request) {
+    controller.add(new CompletionResult(request.offset, 0, [], true));
   }
 }