First pass at asynchronous input loading in dart2js.

sdk/lib/_internal/compiler/implementation/patch_parser.dart

Index: sdk/lib/_internal/compiler/implementation/patch_parser.dart
diff --git a/sdk/lib/_internal/compiler/implementation/patch_parser.dart b/sdk/lib/_internal/compiler/implementation/patch_parser.dart
index 5827a3de7d1144fc58998e8561b5f6139227609f..98e2fb0c6ae2725d4ee75c5ff1d61a6f70152758 100644
--- a/sdk/lib/_internal/compiler/implementation/patch_parser.dart
+++ b/sdk/lib/_internal/compiler/implementation/patch_parser.dart
@@ -114,6 +114,8 @@
 
 library patchparser;
 
+import 'dart:async';
+
 import "tree/tree.dart" as tree;
 import "dart2jslib.dart" as leg;  // CompilerTask, Compiler.
 import "../compiler.dart" as api;
@@ -131,14 +133,12 @@ class PatchParserTask extends leg.CompilerTask {
    * injections to the library, and returns a list of class
    * patches.
    */
-  void patchLibrary(leg.LibraryDependencyHandler handler,
+  Future patchLibrary(leg.LibraryDependencyHandler handler,
                     Uri patchUri, LibraryElement originLibrary) {
-
-    leg.Script script = compiler.readScript(patchUri, null);
-    var patchLibrary = new LibraryElementX(script, null, originLibrary);
-    compiler.withCurrentElement(patchLibrary, () {
+    return compiler.readScript(patchUri, null).then((leg.Script script) {
+      var patchLibrary = new LibraryElementX(script, null, originLibrary);
       handler.registerNewLibrary(patchLibrary);

[ahe, 2013/08/06 16:29:17]

Shouldn't lines 140-141 be inside withCurrentElement(patchLibrary... ?

[Johnni Winther, 2013/08/27 11:05:00]

Done.

-      LinkBuilder<tree.LibraryTag> imports = new LinkBuilder<tree.LibraryTag>();
+      var imports = new LinkBuilder<tree.LibraryTag>();
       compiler.withCurrentElement(patchLibrary.entryCompilationUnit, () {
         // This patches the elements of the patch library into [library].
         // Injected elements are added directly under the compilation unit.
@@ -149,10 +149,11 @@ class PatchParserTask extends leg.CompilerTask {
       // TODO(lrn): These imports end up in the original library and are in
       // scope for the original methods too. This should be fixed.
       compiler.importHelperLibrary(originLibrary);
-      for (tree.LibraryTag tag in imports.toLink()) {
-        compiler.libraryLoader.registerLibraryFromTag(
-            handler, patchLibrary, tag);
-      }
+      // TODO(rnystrom): Remove .toList() here if #11523 is fixed.
+      return Future.forEach(imports.toLink().toList(), (tag) {

[ahe, 2013/08/06 16:29:17]

Shouldn't there be a withCurrentElement here?

[Johnni Winther, 2013/08/27 11:05:00]

Done.

+        return compiler.libraryLoader.registerLibraryFromTag(
+              handler, patchLibrary, tag);
+      });
     });
   }