Show tooltip with local variable value in Observatory debugger

runtime/observatory/lib/src/elements/script_inset.dart

Index: runtime/observatory/lib/src/elements/script_inset.dart
diff --git a/runtime/observatory/lib/src/elements/script_inset.dart b/runtime/observatory/lib/src/elements/script_inset.dart
index 164c134a0b654b689b710d3a2a2736148faec24e..f2610bc7f0181c20bd6909d283e616c38cad43fb 100644
--- a/runtime/observatory/lib/src/elements/script_inset.dart
+++ b/runtime/observatory/lib/src/elements/script_inset.dart
@@ -9,6 +9,7 @@ import 'dart:html';
 import 'observatory_element.dart';
 import 'service_ref.dart';
 import 'package:observatory/service.dart';
+import 'package:observatory/utils.dart';
 import 'package:polymer/polymer.dart';
 
 const nbsp = "\u00A0";
@@ -95,6 +96,24 @@ class CurrentExecutionAnnotation extends Annotation {
   }
 }
 
+class LocalVariableAnnotation extends Annotation {
+  final value;
+
+  LocalVariableAnnotation(LocalVarLocation location, this.value) {
+    line = location.line;
+    columnStart = location.column;
+    columnStop = location.endColumn;
+  }
+
+  void applyStyleTo(element) {
+    if (element == null) {
+      return;  // TODO(rmacnak): Handling overlapping annotations.
+    }
+    element.style.fontWeight = "bold";
+    element.title = "${value.shortName}";
+  }
+}
+
 class CallSiteAnnotation extends Annotation {
   CallSite callSite;
 
@@ -219,6 +238,7 @@ class ScriptInsetElement extends ObservatoryElement {
   @published int startPos;
   @published int endPos;
   @published bool inDebuggerContext = false;
+  @published ObservableList variables;
 
   int _currentLine;
   int _currentCol;
@@ -251,20 +271,24 @@ class ScriptInsetElement extends ObservatoryElement {
   }
 
   void currentPosChanged(oldValue) {
-    update();
+    _updateTask.queue();
     _scrollToCurrentPos();
   }
 
   void startPosChanged(oldValue) {
-    update();
+    _updateTask.queue();
   }
 
   void endPosChanged(oldValue) {
-    update();
+    _updateTask.queue();
   }
 
   void scriptChanged(oldValue) {
-    update();
+    _updateTask.queue();
+  }
+
+  void variablesChanged(oldValue) {
+    _updateTask.queue();
   }
 
   Element a(String text) => new AnchorElement()..text = text;
@@ -288,7 +312,9 @@ class ScriptInsetElement extends ObservatoryElement {
 
   Element container;
 
+  Task _updateTask;
   void update() {
+    assert(_updateTask != null);
     if (script == null) {
       // We may have previously had a script.
       if (container != null) {
@@ -377,6 +403,22 @@ class ScriptInsetElement extends ObservatoryElement {
       }
     }
 
+    // We have local variable information.
+    if (variables != null) {
+      // For each variable.
+      for (var variable in variables) {
+        // Find variable usage locations.
+        var locations = script.scanForLocalVariableLocations(
+              variable['name'], variable['tokenPos'], variable['endTokenPos']);
+
+        // Annotate locations.
+        for (var location in locations) {
+          annotations.add(new LocalVariableAnnotation(location,
+                                                      variable['value']));
+        }
+      }
+    }
+
     annotations.sort();
   }
 
@@ -561,5 +603,8 @@ class ScriptInsetElement extends ObservatoryElement {
     return e;
   }
 
-  ScriptInsetElement.created() : super.created();
+  ScriptInsetElement.created()
+      : super.created() {
+    _updateTask = new Task(update);
+  }
 }