Issue 2429, core implementation and the protocol change

src/liveedit.cc

Index: src/liveedit.cc
diff --git a/src/liveedit.cc b/src/liveedit.cc
index 574a37691c0a0e99e0e46617455d734ff7e50d2c..f2b9977efa4fc42d4280bede710319d3cf989f57 100644
--- a/src/liveedit.cc
+++ b/src/liveedit.cc
@@ -925,11 +925,68 @@ JSArray* LiveEdit::GatherCompileInfo(Handle<Script> script,
   Handle<Object> original_source = Handle<Object>(script->source());
   script->set_source(*source);
   isolate->set_active_function_info_listener(&listener);
-  CompileScriptForTracker(isolate, script);
+
+  Handle<Object> rethrow_exception;
+  {
+    // Creating TryCatch from public API is currently the only way to get
+    // message object. Without TryCatch the message object won't even be
+    // prepared at all.
+    v8::TryCatch try_catch;
+    try_catch.SetVerbose(true);
+
+    // A logical 'try' section.
+    CompileScriptForTracker(isolate, script);
+
+    // A logical 'catch' section.
+    if (isolate->has_pending_exception()) {
+      isolate->ReportPendingMessages();
+      isolate->clear_pending_exception();

[Yang, 2012/11/29 16:38:57]

If I'm not mistaken, ReportPendingMessages() already clears the pending
exception and the pending message.

[Peter Rybin, 2012/11/29 23:16:05]

It does clear message. I don't see that it clears exception though.
1 line removed.

+      isolate->clear_pending_message();
+    }
+    if (!try_catch.Exception().IsEmpty()) {

[Yang, 2012/11/29 16:38:57]

use try_catch.HasCaught() seems cleaner.

[Peter Rybin, 2012/11/29 23:16:05]

Done.

+      Handle<Object> exception =
+          Utils::OpenHandle(*try_catch.Exception(), false);
+
+      // If possible, copy positions from message object to exception object.
+      if (exception->IsJSObject() && !try_catch.Message().IsEmpty()) {

[Yang, 2012/11/29 16:38:57]

It seems that GetLineNumber() and the Get*Column() methods call into javascript
to calculate those from start position and end position.

I suggest attaching only  message->script(), message->start_position() and
message->end_position() to the error object, and use script.locationFromPosition
to compute the rest when the exception is passed into javascript.

[Peter Rybin, 2012/11/29 23:16:05]

Done.

+        Handle<JSObject> exception_struct = Handle<JSObject>::cast(exception);
+
+        Factory* factory = isolate->factory();
+        JSReceiver::SetProperty(exception_struct,
+            factory->LookupAsciiSymbol("startLine"),
+            Handle<Smi>(Smi::FromInt(try_catch.Message()->GetLineNumber())),
+            NONE, kNonStrictMode);
+        JSReceiver::SetProperty(exception_struct,
+            factory->LookupAsciiSymbol("startPosition"),
+            Handle<Smi>(Smi::FromInt(try_catch.Message()->GetStartPosition())),
+            NONE, kNonStrictMode);
+        JSReceiver::SetProperty(exception_struct,
+            factory->LookupAsciiSymbol("endPosition"),
+            Handle<Smi>(Smi::FromInt(try_catch.Message()->GetEndPosition())),
+            NONE, kNonStrictMode);
+        JSReceiver::SetProperty(exception_struct,
+            factory->LookupAsciiSymbol("startColumn"),
+            Handle<Smi>(Smi::FromInt(try_catch.Message()->GetStartColumn())),
+            NONE, kNonStrictMode);
+        JSReceiver::SetProperty(exception_struct,
+            factory->LookupAsciiSymbol("endColumn"),
+            Handle<Smi>(Smi::FromInt(try_catch.Message()->GetEndColumn())),
+            NONE, kNonStrictMode);
+      }
+
+      rethrow_exception = exception;
+    }
+  }
+
   isolate->set_active_function_info_listener(NULL);
   script->set_source(*original_source);
 
-  return *(listener.GetResult());
+  if (rethrow_exception.is_null()) {

[Yang, 2012/11/29 16:38:57]

Would it be possible to use try_catch.ReThrow()?

[Peter Rybin, 2012/11/29 23:16:05]

I don't see a nice way to reach TryCatch outside from block scope above.

+    return *(listener.GetResult());
+  } else {
+    isolate->Throw(*rethrow_exception);
+    return 0;
+  }
 }