Move Compiler.libraries to LibraryLoader.

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

Index: sdk/lib/_internal/compiler/implementation/library_loader.dart
diff --git a/sdk/lib/_internal/compiler/implementation/library_loader.dart b/sdk/lib/_internal/compiler/implementation/library_loader.dart
index dfb3258e055c11ccafa8a6642882fce642a84e14..71ebc2deebd6751d642ec270ca6ca39513914f89 100644
--- a/sdk/lib/_internal/compiler/implementation/library_loader.dart
+++ b/sdk/lib/_internal/compiler/implementation/library_loader.dart
@@ -123,24 +123,26 @@ import 'util/util.dart' show Link, LinkBuilder;
 abstract class LibraryLoaderTask implements CompilerTask {
   factory LibraryLoaderTask(Compiler compiler) = _LibraryLoaderTask;
 
-  /**
-   * Loads the library specified by the [resolvedUri] and returns its
-   * [LibraryElement].
-   *
-   * If the library is not already loaded, the method creates the
-   * [LibraryElement] for the library and computes the import/export scope,
-   * loading and computing the import/export scopes of all required libraries in
-   * the process. The method handles cyclic dependency between libraries.
-   */
+  /// Returns all libraries that have been loaded.
+  Iterable<LibraryElement> get libraries;
+
+  /// Looks up the library with the [canonicalUri].
+  LibraryElement lookupLibrary(Uri canonicalUri);
+
+  /// Loads the library specified by the [resolvedUri] and returns its
+  /// [LibraryElement].
+  ///
+  /// If the library is not already loaded, the method creates the
+  /// [LibraryElement] for the library and computes the import/export scope,
+  /// loading and computing the import/export scopes of all required libraries
+  /// in the process. The method handles cyclic dependency between libraries.
   Future<LibraryElement> loadLibrary(Uri resolvedUri);
 
-  /// Reset the library loader task to prepare for compilation. This is used
-  /// for incremental compilation.
-  void reset();
-
-  /// Reuse [library] from a previous compilation. This is used for incremental
-  /// compilation.
-  void reuseLibrary(LibraryElement library);
+  /// Reset the library loader task to prepare for compilation. If provided,
+  /// libraries matching [reuseLibrary] are reused.
+  ///
+  /// This method is used for incremental compilation.
+  void reset({bool reuseLibrary(LibraryElement library)});
 }
 
 /// Handle for creating synthesized/patch libraries during library loading.
@@ -246,6 +248,8 @@ class _LibraryLoaderTask extends CompilerTask implements LibraryLoaderTask {
   _LibraryLoaderTask(Compiler compiler) : super(compiler);
   String get name => 'LibraryLoader';
 
+  final Map<Uri, LibraryElement> libraryCanonicalUriMap =
+      new Map<Uri, LibraryElement>();
   final Map<Uri, LibraryElement> libraryResourceUriMap =
       new Map<Uri, LibraryElement>();
   final Map<String, LibraryElement> libraryNames =
@@ -253,16 +257,34 @@ class _LibraryLoaderTask extends CompilerTask implements LibraryLoaderTask {
 
   LibraryDependencyHandler currentHandler;
 
-  void reset() {
+  Iterable<LibraryElement> get libraries => libraryCanonicalUriMap.values;
+
+  LibraryElement lookupLibrary(Uri canonicalUri) {
+    return libraryCanonicalUriMap[canonicalUri];
+  }
+
+  void reset({bool reuseLibrary(LibraryElement library)}) {
     assert(currentHandler == null);
+    Iterable<LibraryElement> libraries =
+        new List.from(libraryCanonicalUriMap.values);
+
+    libraryCanonicalUriMap.clear();
     libraryResourceUriMap.clear();
     libraryNames.clear();
+
+    if (reuseLibrary == null) return;
+
+    libraries.where(reuseLibrary).forEach(mapLibrary);
   }
 
-  void reuseLibrary(LibraryElement library) {
-    String name = library.getLibraryOrScriptName();
+  /// Insert [library] in the internal maps. Used for compiler reuse.
+  void mapLibrary(LibraryElement library) {
+    libraryCanonicalUriMap[library.canonicalUri] = library;
+
     Uri resourceUri = library.entryCompilationUnit.script.resourceUri;
     libraryResourceUriMap[resourceUri] = library;
+
+    String name = library.getLibraryOrScriptName();
     libraryNames[name] = library;
   }
 
@@ -488,7 +510,7 @@ class _LibraryLoaderTask extends CompilerTask implements LibraryLoaderTask {
     Uri readableUri =
         compiler.translateResolvedUri(importingLibrary, resolvedUri, node);
     if (readableUri == null) return new Future.value();
-    LibraryElement library = compiler.libraries[resolvedUri.toString()];
+    LibraryElement library = libraryCanonicalUriMap[resolvedUri];
     if (library != null) {
       return new Future.value(library);
     }
@@ -500,7 +522,7 @@ class _LibraryLoaderTask extends CompilerTask implements LibraryLoaderTask {
             compiler.withCurrentElement(element, () {
               handler.registerNewLibrary(element);
               native.maybeEnableNative(compiler, element);
-              compiler.libraries[resolvedUri.toString()] = element;
+              libraryCanonicalUriMap[resolvedUri] = element;
               compiler.scanner.scanLibrary(element);
             });
             return processLibraryTags(handler, element).then((_) {