Add hook for listening to implicitly analyzed files

pkg/analyzer/lib/src/context/context.dart

Index: pkg/analyzer/lib/src/context/context.dart
diff --git a/pkg/analyzer/lib/src/context/context.dart b/pkg/analyzer/lib/src/context/context.dart
index 9c0c9808356e71d72075280b178eba1551f8733c..3199f85bf1e32f9d9a3c0821b9964c06e54fa6c0 100644
--- a/pkg/analyzer/lib/src/context/context.dart
+++ b/pkg/analyzer/lib/src/context/context.dart
@@ -167,6 +167,12 @@ class AnalysisContextImpl implements InternalAnalysisContext {
   StreamController<SourcesChangedEvent> _onSourcesChangedController;
 
   /**
+   * A subscription for a stream of events indicating when files are (and are
+   * not) being implicitly analyzed.
+   */
+  StreamController<AnalyzedSourcesEvent> _analyzedSourcesController;

[Paul Berry, 2015/07/15 19:50:01]

How about naming this "_implicitlyAnalyzedSourcesController", just so that
there's no confusion about explicit vs. implicit sources.

+
+  /**
    * The listeners that are to be notified when various analysis results are
    * produced in this context.
    */
@@ -220,6 +226,8 @@ class AnalysisContextImpl implements InternalAnalysisContext {
         _taskManager, <WorkManager>[dartWorkManager, htmlWorkManager], this);
     _onSourcesChangedController =
         new StreamController<SourcesChangedEvent>.broadcast();
+    _analyzedSourcesController =
+        new StreamController<AnalyzedSourcesEvent>.broadcast();
   }
 
   @override
@@ -281,6 +289,10 @@ class AnalysisContextImpl implements InternalAnalysisContext {
   }
 
   @override
+  Stream<AnalyzedSourcesEvent> get analyzedSources =>
+      _analyzedSourcesController.stream;
+
+  @override
   set contentCache(ContentCache value) {
     _contentCache = value;
   }
@@ -728,6 +740,9 @@ class AnalysisContextImpl implements InternalAnalysisContext {
         entry.modificationTime = getModificationStamp(target);
       }
       _cache.put(entry);
+      if (target is Source) {
+        _analyzedSourcesController.add(new AnalyzedSourcesEvent(target, true));
+      }
     }
     return entry;
   }
@@ -1219,7 +1234,7 @@ class AnalysisContextImpl implements InternalAnalysisContext {
     for (Source source in missingSources) {
       if (getLibrariesContaining(source).isEmpty &&
           getLibrariesDependingOn(source).isEmpty) {
-        _cache.remove(source);
+        _removeFromCache(source);
         removalCount++;
       }
     }
@@ -1427,6 +1442,9 @@ class AnalysisContextImpl implements InternalAnalysisContext {
     entry.modificationTime = getModificationStamp(source);
     entry.explicitlyAdded = explicitlyAdded;
     _cache.put(entry);
+    if (!explicitlyAdded) {
+      _analyzedSourcesController.add(new AnalyzedSourcesEvent(source, true));
+    }
     return entry;
   }
 
@@ -1637,6 +1655,13 @@ class AnalysisContextImpl implements InternalAnalysisContext {
     }
   }
 
+  void _removeFromCache(Source source) {
+    CacheEntry entry = _cache.remove(source);
+    if (entry != null && entry.explicitlyAdded) {
+      _analyzedSourcesController.add(new AnalyzedSourcesEvent(source, false));
+    }
+  }
+
   /**
    * Remove the given [source] from the priority order if it is in the list.
    */
@@ -1769,7 +1794,7 @@ class AnalysisContextImpl implements InternalAnalysisContext {
    * Record that the given [source] has been removed.
    */
   void _sourceRemoved(Source source) {
-    _cache.remove(source);
+    _removeFromCache(source);
     _removeFromPriorityOrder(source);
   }