Support serialization of the compiler backbone.

pkg/compiler/lib/src/serialization/task.dart

Index: pkg/compiler/lib/src/serialization/task.dart
diff --git a/pkg/compiler/lib/src/serialization/task.dart b/pkg/compiler/lib/src/serialization/task.dart
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+++ b/pkg/compiler/lib/src/serialization/task.dart
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+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library dart2js.serialization.task;
+
+import '../dart2jslib.dart';
+import '../elements/elements.dart';
+
+/// Task that supports deserialization of elements.
+class SerializationTask extends CompilerTask {
+  SerializationTask(Compiler compiler) : super(compiler);
+
+  DeserializerSystem deserializer;
+
+  String get name => 'Serialization';
+
+  /// Returns the [LibraryElement] for [resolvedUri] if available from
+  /// serialization.
+  LibraryElement readLibrary(Uri resolvedUri) {
+    if (deserializer == null) return null;
+    return deserializer.readLibrary(resolvedUri);
+  }
+
+  /// Returns `true` if [element] has been deserialized.
+  bool isDeserialized(Element element) {
+    return deserializer != null && deserializer.isDeserialized(element);
+  }
+
+  /// Creates the [ResolutionWorkItem] for the deserialized [element].
+  ResolutionWorkItem createResolutionWorkItem(
+      Element element, ItemCompilationContext context) {
+    assert(deserializer != null);
+    assert(isDeserialized(element));
+    return new DeserializedResolutionWorkItem(
+        element, context, deserializer.computeWorldImpact(element));
+  }
+}
+
+/// A [ResolutionWorkItem] for a deserialized element.
+///
+/// This will not resolve the element but only compute the [WorldImpact].
+class DeserializedResolutionWorkItem implements ResolutionWorkItem {
+  final Element element;
+  final ItemCompilationContext compilationContext;
+  final WorldImpact worldImpact;
+  bool _isAnalyzed = false;
+
+  DeserializedResolutionWorkItem(
+      this.element, this.compilationContext, this.worldImpact);
+
+  @override
+  bool get isAnalyzed => _isAnalyzed;
+
+  @override
+  WorldImpact run(Compiler compiler, ResolutionEnqueuer world) {
+    _isAnalyzed = true;
+    world.registerResolvedElement(element);
+    return worldImpact;
+  }
+}
+
+/// The interface for a system that supports deserialization of libraries and
+/// elements.
+abstract class DeserializerSystem {
+  LibraryElement readLibrary(Uri resolvedUri);
+  bool isDeserialized(Element element);
+  WorldImpact computeWorldImpact(Element element);
+}