Add MultiSourceInformationStrategy

pkg/compiler/lib/src/io/start_end_information.dart

 // 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.
 
 /// Source information system that maps spans of Dart AST nodes to spans of
 /// JavaScript nodes.
 
 library dart2js.source_information.start_end;
 
+import 'package:front_end/src/fasta/scanner.dart' show Token;
+
 import '../common.dart';
 import '../diagnostics/messages.dart' show MessageTemplate;
 import '../elements/elements.dart' show ResolvedAst, ResolvedAstKind;
 import '../js/js.dart' as js;
 import '../js/js_source_mapping.dart';
-import 'package:front_end/src/fasta/scanner.dart' show Token;
 import '../tree/tree.dart' show Node;
 import 'source_file.dart';
 import 'source_information.dart';
 
 /// Source information that contains start source position and optionally an
 /// end source position.
 class StartEndSourceInformation extends SourceInformation {
   @override
   final SourceLocation startPosition;
 
@@ skipping 84 matching lines @@
 class StartEndSourceInformationStrategy
     extends JavaScriptSourceInformationStrategy {
   const StartEndSourceInformationStrategy();
 
   @override
   SourceInformationBuilder createBuilderForContext(ResolvedAst resolvedAst) {
     return new StartEndSourceInformationBuilder(resolvedAst);
   }
 
   @override
-  SourceInformationProcessor createProcessor(SourceMapper sourceMapper) {
-    return new StartEndSourceInformationProcessor(sourceMapper);
+  SourceInformationProcessor createProcessor(
+      SourceMapperProvider provider, SourceInformationReader reader) {
+    return new StartEndSourceInformationProcessor(provider, reader);
   }
 }
 
 class StartEndSourceInformationProcessor extends SourceInformationProcessor {
+  /// The id for this source information engine.
+  ///
+  /// The id is added to the source map file in an extra "engine" property and
+  /// serves as a version number for the engine.
+  ///
+  /// The version history of this engine is:
+  ///
+  ///   v1: The initial version with an id.
+  static const String id = 'v1';
+
   final SourceMapper sourceMapper;
+  final SourceInformationReader reader;
 
   /// Used to track whether a terminating source location marker has been
   /// registered for the top-most node with source information.
   bool hasRegisteredRoot = false;
 
   /// The root of the tree. Used to add a [NoSourceLocationMarker] to the start
   /// of the output.
   js.Node root;
 
   /// The root of the current subtree with source information. Used to add
   /// [NoSourceLocationMarker] after areas with source information.
   js.Node subRoot;
 
-  StartEndSourceInformationProcessor(this.sourceMapper);
+  StartEndSourceInformationProcessor(SourceMapperProvider provider, this.reader)
+      : this.sourceMapper = provider.createSourceMapper(id);
 
   void onStartPosition(js.Node node, int startPosition) {
     if (root == null) {
       root = node;
       sourceMapper.register(
           node, startPosition, const NoSourceLocationMarker());
     }
-    if (subRoot == null && node.sourceInformation != null) {
+    if (subRoot == null && reader.getSourceInformation(node) != null) {
       subRoot = node;
     }
   }
 
   @override
   void onPositions(
       js.Node node, int startPosition, int endPosition, int closingPosition) {
-    if (node.sourceInformation != null) {
-      StartEndSourceInformation sourceInformation = node.sourceInformation;
+    StartEndSourceInformation sourceInformation =
+        reader.getSourceInformation(node);
+    if (sourceInformation != null) {
       sourceMapper.register(
           node, startPosition, sourceInformation.startPosition);
       if (sourceInformation.endPosition != null) {
         sourceMapper.register(node, endPosition, sourceInformation.endPosition);
       }
       if (!hasRegisteredRoot) {
         sourceMapper.register(node, endPosition, null);
         hasRegisteredRoot = true;
       }
       if (node == subRoot) {
@@ skipping 69 matching lines @@
 
   @override
   SourceInformation buildIf(Node node) => buildGeneric(node);
 
   @override
   SourceInformationBuilder forContext(ResolvedAst resolvedAst,
       {SourceInformation sourceInformation}) {
     return new StartEndSourceInformationBuilder(resolvedAst);
   }
 }