Make navigation support consistent with completion support

pkg/analyzer_plugin/lib/utilities/navigation/navigation.dart

Index: pkg/analyzer_plugin/lib/utilities/navigation/navigation.dart
diff --git a/pkg/analyzer_plugin/lib/utilities/navigation.dart b/pkg/analyzer_plugin/lib/utilities/navigation/navigation.dart
similarity index 50%
rename from pkg/analyzer_plugin/lib/utilities/navigation.dart
rename to pkg/analyzer_plugin/lib/utilities/navigation/navigation.dart
index 4db996a49bbc3fb4274a9e196dc541d289962a9c..a7876195ffa680aeb65dbb0e5cfeda807559c336 100644
--- a/pkg/analyzer_plugin/lib/utilities/navigation.dart
+++ b/pkg/analyzer_plugin/lib/utilities/navigation/navigation.dart
@@ -2,12 +2,14 @@
 // 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.
 
-import 'package:analyzer/src/dart/analysis/driver.dart';
+import 'package:analyzer/dart/analysis/results.dart';
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart'
     show ElementKind, Location;
 import 'package:analyzer_plugin/protocol/protocol_generated.dart';
-import 'package:analyzer_plugin/src/utilities/navigation.dart';
+import 'package:analyzer_plugin/src/utilities/navigation/navigation.dart';
+import 'package:analyzer_plugin/utilities/generator.dart';
 
 /**
  * An object that [NavigationContributor]s use to record navigation regions.
@@ -30,12 +32,11 @@ abstract class NavigationCollector {
  */
 abstract class NavigationContributor {
   /**
-   * Contribute navigation regions for a subset of the content of the given
-   * [source] into the given [collector]. The subset is specified by the
-   * [offset] and [length]. The [driver] can be used to access analysis results.
+   * Contribute navigation regions for the portion of the file specified by the
+   * given [request] into the given [collector].
    */
-  void computeNavigation(NavigationCollector collector,
-      AnalysisDriverGeneric driver, String filePath, int offset, int length);
+  void computeNavigation(
+      NavigationRequest request, NavigationCollector collector);
 }
 
 /**
@@ -45,36 +46,27 @@ abstract class NavigationContributor {
  */
 class NavigationGenerator {
   /**
-   * The driver to be passed in to the contributors.
-   */
-  final AnalysisDriverGeneric driver;
-
-  /**
    * The contributors to be used to generate the navigation data.
    */
   final List<NavigationContributor> contributors;
 
   /**
-   * Initialize a newly created navigation generator.
+   * Initialize a newly created navigation generator to use the given
+   * [contributors].
    */
-  NavigationGenerator(this.driver, this.contributors);
+  NavigationGenerator(this.contributors);
 
   /**
-   * Create an 'analysis.navigation' notification for the file with the given
-   * [filePath]. If any of the contributors throws an exception, also create a
-   * non-fatal 'plugin.error' notification.
+   * Create an 'analysis.navigation' notification for the portion of the file
+   * specified by the given [request]. If any of the contributors throws an
+   * exception, also create a non-fatal 'plugin.error' notification.
    */
-  List<Notification> generateNavigationNotification(String filePath) {
-    // TODO(brianwilkerson) Consider not passing a driver in (to either the
-    // NavigationGenerator constructor or computeNavigation) and replace the
-    // filePath with an AnalysisResult that then gets passed in to
-    // computeNavigation. That would allow contributors to use previously
-    // computed results rather than re-compute them.
+  GeneratorResult generateNavigationNotification(NavigationRequest request) {
     List<Notification> notifications = <Notification>[];
     NavigationCollectorImpl collector = new NavigationCollectorImpl();
     for (NavigationContributor contributor in contributors) {
       try {
-        contributor.computeNavigation(collector, driver, filePath, null, null);
+        contributor.computeNavigation(request, collector);
       } catch (exception, stackTrace) {
         notifications.add(new PluginErrorParams(
                 false, exception.toString(), stackTrace.toString())
@@ -82,9 +74,39 @@ class NavigationGenerator {
       }
     }
     collector.createRegions();
-    notifications.add(new AnalysisNavigationParams(
-            filePath, collector.regions, collector.targets, collector.files)
+    notifications.add(new AnalysisNavigationParams(request.result.path,
+            collector.regions, collector.targets, collector.files)
         .toNotification());
-    return notifications;
+    return new GeneratorResult(null, notifications);
   }
 }
+
+/**
+ * The information about a requested set of navigation information.
+ *
+ * Clients may not extend, implement or mix-in this class.
+ */
+abstract class NavigationRequest {
+  /**
+   * Return the length of the region within the source for which navigation
+   * regions are being requested.
+   */
+  int get length;
+
+  /**
+   * Return the offset of the region within the source for which navigation
+   * regions are being requested.
+   */
+  int get offset;
+
+  /**
+   * Return the resource provider associated with this request.
+   */
+  ResourceProvider get resourceProvider;
+
+  /**
+   * The analysis result for the file in which the navigation regions are being
+   * requested.
+   */
+  ResolveResult get result;
+}