--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.chromium.debug.ui/src/org/chromium/debug/ui/editors/JsDebugTextHover.java	Wed Dec 23 17:13:18 2009 -0800
@@ -0,0 +1,62 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.debug.ui.editors;
+
+import org.chromium.debug.core.model.StackFrame;
+import org.chromium.debug.core.util.JsValueStringifier;
+import org.chromium.sdk.CallFrame;
+import org.chromium.sdk.JsVariable;
+import org.eclipse.core.runtime.IAdaptable;
+import org.eclipse.debug.ui.DebugUITools;
+import org.eclipse.jface.text.IDocument;
+import org.eclipse.jface.text.IRegion;
+import org.eclipse.jface.text.ITextHover;
+import org.eclipse.jface.text.ITextViewer;
+
+/**
+ * Supplies a hover for JavaScript expressions while on a breakpoint.
+ */
+public class JsDebugTextHover implements ITextHover {
+
+  private static final JsValueStringifier STRINGIFIER = new JsValueStringifier();
+
+  public String getHoverInfo(ITextViewer textViewer, IRegion hoverRegion) {
+    IDocument doc = textViewer.getDocument();
+    String expression = JavascriptUtil.extractSurroundingJsIdentifier(doc, hoverRegion.getOffset());
+    if (expression == null) {
+      return null;
+    }
+
+    IAdaptable context = DebugUITools.getDebugContext();
+    if (context == null) { // debugger not active
+      return null;
+    }
+
+    StackFrame frame = (StackFrame) context.getAdapter(StackFrame.class);
+    if (frame == null) { // not a stackframe-related context
+      return null;
+    }
+
+    final JsVariable[] result = new JsVariable[1];
+    frame.getCallFrame().evaluateSync(expression, new CallFrame.EvaluateCallback() {
+      public void success(JsVariable var) {
+        result[0] = var;
+      }
+      public void failure(String errorMessage) {
+      }
+    });
+    if (result[0] == null) {
+      return null;
+    }
+
+    return STRINGIFIER.render(result[0].getValue());
+  }
+
+  public IRegion getHoverRegion(ITextViewer textViewer, int offset) {
+    IDocument doc = textViewer.getDocument();
+    return JavascriptUtil.getSurroundingIdentifierRegion(doc, offset, false);
+  }
+
+}