Add AnalysisContext.onResultInvalidated(descriptor).

pkg/analyzer/lib/src/generated/engine.dart

Index: pkg/analyzer/lib/src/generated/engine.dart
diff --git a/pkg/analyzer/lib/src/generated/engine.dart b/pkg/analyzer/lib/src/generated/engine.dart
index 57d35d91212d749e4133189ddc1390cfaf43d1d1..2518b4f2fe36e1aa7912809de48ce48602cde3e1 100644
--- a/pkg/analyzer/lib/src/generated/engine.dart
+++ b/pkg/analyzer/lib/src/generated/engine.dart
@@ -520,6 +520,12 @@ abstract class AnalysisContext {
   Stream<ComputedResult> onResultComputed(ResultDescriptor descriptor);
 
   /**
+   * Return the stream that is notified when a result with the given
+   * [descriptor] is invalidated.
+   */
+  Stream<InvalidatedResult> onResultInvalidated(ResultDescriptor descriptor);
+
+  /**
    * Parse the content of the given [source] to produce an AST structure. The
    * resulting AST structure may or may not be resolved, and may have a slightly
    * different structure depending upon whether it is resolved.
@@ -2059,6 +2065,31 @@ abstract class InternalAnalysisContext implements AnalysisContext {
 }
 
 /**
+ * [InvalidatedResult] describes an invalidated result.
+ */
+class InvalidatedResult<V> {

[Brian Wilkerson, 2016/03/08 17:54:31]

Maybe rename to InvalidatedResultEvent?

[scheglov, 2016/03/08 18:24:44]

Done.

+  /**
+   * The target in which the result was invalidated.
+   */
+  final CacheEntry entry;

[Brian Wilkerson, 2016/03/08 17:54:31]

I really don't want CacheEntry to be part of the public API. What information
from it are you expecting to need? Is it just the target, as implied by the
comment?

[scheglov, 2016/03/08 18:24:45]

I changed the set of fields to be like in ComputedResult, so now it does not
expose CacheEntry.

+
+  /**
+   * The descriptor of the result which was invalidated.
+   */
+  final ResultDescriptor<V> descriptor;
+
+  /**
+   * The value of the result which was invalidated.

[Brian Wilkerson, 2016/03/08 17:54:31]

"which was" --> "before it was"?

[scheglov, 2016/03/08 18:24:44]

Done.

+   */
+  final V value;
+
+  InvalidatedResult(this.entry, this.descriptor, this.value);
+
+  @override
+  String toString() => '$descriptor of ${entry.target}';

[Brian Wilkerson, 2016/03/08 17:54:31]

"'$d" --> "'Invalidated $d"? Otherwise it's too close to ComputedResult.
Speaking of which, maybe this object should contain a computed result and a
value instead of the current properties.

[scheglov, 2016/03/08 18:24:44]

Done.

+}
+
+/**
  * An object that can be used to receive information about errors within the
  * analysis engine. Implementations usually write this information to a file,
  * but can also record the information for later use (such as during testing) or