Generated source mapping through CPS.

pkg/compiler/lib/src/helpers/helpers.dart

 // Copyright (c) 2014, 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 for debugging helpers. The unittest analyze_unused_test checks that
 /// the helper are not used in production code.
 
 library dart2js.helpers;
 
 import 'dart:async' show EventSink;
@@ skipping 75 matching lines @@
 ReportHere get reportHere {
   enableDebugMode();
   return _reportHere;
 }
 
 /// Implementation of [reportHere]
 _reportHere(Compiler compiler, Spannable node, String debugMessage) {
   compiler.reportInfo(node,
       MessageKind.GENERIC, {'text': 'HERE: $debugMessage'});
 }
+
+/// Set of tracked objects used by [track] and [ifTracked].

[karlklose, 2015/07/10 12:44:40]

Maybe this change should be in its own CL.

[Johnni Winther, 2015/07/10 13:26:38]

Maybe. It was used to create this CL.

+var _trackedObjects = new Set();
+
+/// Global default value for the `printTrace` option of [track] and [ifTracked].
+bool trackWithTrace = false;
+
+/// If [doTrack] is `true`, add [object] to the set of tracked objects.
+///
+/// If tracked, [message] is printed along the hash code and toString of [object].

[karlklose, 2015/07/10 12:44:40]

Long line.

[Johnni Winther, 2015/07/10 13:26:38]

Done.

+/// If [printTrace] is `true` a trace printed additionally. If [printTrace] is
+/// `null`, [trackWithTrace] determines whether a trace is printed.
+///
+/// [object] is returned as the result of the method.
+track(bool doTrack, Object object, String message, {bool printTrace}) {
+  if (!doTrack) return object;
+  _trackedObjects.add(object);
+  String msg = 'track: ${object.hashCode}:$object:$message';
+  if (printTrace == null) printTrace = trackWithTrace;
+  if (printTrace) {
+    trace(msg);
+  } else {
+    debugPrint(msg);
+  }
+  return object;
+}
+
+/// Returns `true` if [object] is in the set of tracked objects.
+///
+/// If [message] is provided it is printed along the hash code and toString of
+/// [object]. If [printTrace] is `true` a trace printed additionally. If
+/// [printTrace] is `null`, [trackWithTrace] determines whether a trace is
+/// printed.
+bool ifTracked(Object object, {String message, bool printTrace}) {
+  if (_trackedObjects.contains(object)) {
+    if (message != null) {
+      String msg = 'tracked: ${object.hashCode}:$object:$message';
+      if (printTrace == null) printTrace = trackWithTrace;
+      if (printTrace) {
+        trace(msg);
+      } else {
+        debugPrint(msg);
+      }
+    }
+    return true;
+  }
+  return false;
+}