Chain SummaryResynthesizer(s).

pkg/analyzer/lib/src/summary/resynthesize.dart

Index: pkg/analyzer/lib/src/summary/resynthesize.dart
diff --git a/pkg/analyzer/lib/src/summary/resynthesize.dart b/pkg/analyzer/lib/src/summary/resynthesize.dart
index 3a43e0e1f90e71f777a0d7c967b09739c07ad061..78ace0e1ad2a152a5e5b48a578ceac4847e33a40 100644
--- a/pkg/analyzer/lib/src/summary/resynthesize.dart
+++ b/pkg/analyzer/lib/src/summary/resynthesize.dart
@@ -27,11 +27,28 @@ typedef PrelinkedLibrary GetPrelinkedSummaryCallback(String uri);
 typedef UnlinkedUnit GetUnlinkedSummaryCallback(String uri);
 
 /**
+ * Callback used by [SummaryResynthesizer] to check whether it can access
+ * summaries of the library with the given [uri].
+ */
+typedef bool HasLibrarySummaryCallback(String uri);
+
+/**
  * Implementation of [ElementResynthesizer] used when resynthesizing an element
  * model from summaries.
  */
 class SummaryResynthesizer extends ElementResynthesizer {
   /**
+   * The parent [SummaryResynthesizer] which is asked to resynthesis elements
+   * before this resynthesizer attempts to do this. Can be `null`.
+   */
+  final SummaryResynthesizer parent;
+
+  /**
+   * Callback used to check whether summaries for a given URI can be accessed.
+   */
+  final HasLibrarySummaryCallback hasLibrarySummary;
+
+  /**
    * Callback used to obtain the prelinked summary for a given URI.
    */
   final GetPrelinkedSummaryCallback getPrelinkedSummary;
@@ -72,8 +89,14 @@ class SummaryResynthesizer extends ElementResynthesizer {
   final Map<String, LibraryElement> _resynthesizedLibraries =
       <String, LibraryElement>{};
 
-  SummaryResynthesizer(AnalysisContext context, this.typeProvider,
-      this.getPrelinkedSummary, this.getUnlinkedSummary, this.sourceFactory)
+  SummaryResynthesizer(
+      this.parent,
+      AnalysisContext context,
+      this.typeProvider,
+      this.hasLibrarySummary,
+      this.getPrelinkedSummary,
+      this.getUnlinkedSummary,
+      this.sourceFactory)
       : super(context);
 
   /**
@@ -83,21 +106,30 @@ class SummaryResynthesizer extends ElementResynthesizer {
 
   @override
   Element getElement(ElementLocation location) {
-    if (location.components.length == 1) {
-      return getLibraryElement(location.components[0]);
-    } else if (location.components.length == 3) {
-      String uri = location.components[0];
+    List<String> components = location.components;
+    // Ask the parent resynthesizer.
+    if (parent != null && components.length >= 1) {
+      String libraryUri = components[0];

[Paul Berry, 2016/01/14 18:54:39]

Personally I would move this up to line 110, and delete lines 119 and 122.  It's
clearer, and the only behavioral difference is that it changes the type of
exception that would be thrown in the case where location.components is the
empty list (which should never happen anyway).

Your call, though.

[scheglov, 2016/01/14 22:43:08]

Done.

+      if (parent.hasLibrarySummary(libraryUri)) {
+        return parent.getElement(location);
+      }
+    }
+    // Resynthesize locally.
+    if (components.length == 1) {
+      String libraryUri = components[0];
+      return getLibraryElement(libraryUri);
+    } else if (components.length == 3) {
+      String libraryUri = components[0];
       Map<String, Map<String, Element>> libraryMap =
-          _resynthesizedElements[uri];
+          _resynthesizedElements[libraryUri];
       if (libraryMap == null) {
-        getLibraryElement(uri);
-        libraryMap = _resynthesizedElements[uri];
+        getLibraryElement(libraryUri);
+        libraryMap = _resynthesizedElements[libraryUri];
         assert(libraryMap != null);
       }
-      Map<String, Element> compilationUnitElements =
-          libraryMap[location.components[1]];
+      Map<String, Element> compilationUnitElements = libraryMap[components[1]];
       if (compilationUnitElements != null) {
-        Element element = compilationUnitElements[location.components[2]];
+        Element element = compilationUnitElements[components[2]];
         if (element != null) {
           return element;
         }
@@ -113,6 +145,9 @@ class SummaryResynthesizer extends ElementResynthesizer {
    * hasn't been resynthesized already.
    */
   LibraryElement getLibraryElement(String uri) {
+    if (parent != null && parent.hasLibrarySummary(uri)) {
+      return parent.getLibraryElement(uri);
+    }
     return _resynthesizedLibraries.putIfAbsent(uri, () {
       PrelinkedLibrary serializedLibrary = getPrelinkedSummary(uri);
       List<UnlinkedUnit> serializedUnits = <UnlinkedUnit>[
@@ -845,7 +880,8 @@ class _LibraryResynthesizer {
     if (type.paramReference != 0) {
       // TODO(paulberry): make this work for generic methods.
       return currentTypeParameters[
-          currentTypeParameters.length - type.paramReference].type;
+              currentTypeParameters.length - type.paramReference]
+          .type;
     } else {
       // TODO(paulberry): handle references to things other than classes (note:
       // this should only occur in the case of erroneous code).