Wrap enter/leave user code into RAII.

lib/Interpreter/EnterUserCodeRTTI.h

@@ -0,0 +1,36 @@
+//------------------------------------------------------------------------------
+// CLING - the C++ LLVM-based InterpreterG :)
+// author:  Vassil Vassilev <vvasilev@cern.ch>
+//
+// This file is dual-licensed: you can choose to license it under the University
+// of Illinois Open Source License or the GNU Lesser General Public License. See
+// LICENSE.TXT for details.
+//------------------------------------------------------------------------------
+
+#ifndef CLING_ENTERUSERCODERTTI_H
+#define CLING_ENTERUSERCODERTTI_H
+
+#include "cling/Interpreter/Interpreter.h"
+#include "cling/Interpreter/InterpreterCallbacks.h"
+
+namespace cling {
+  ///\brief Unlocks and then upon destruction locks the interpreter again.
+  struct EnterUserCodeRTTI {
+    InterpreterCallbacks* fCallbacks; // callbacks used to un/lock.
+    EnterUserCodeRTTI(InterpreterCallbacks* callbacks): fCallbacks(callbacks)
+    {
+      if (fCallbacks)
+        fCallbacks->EnteringUserCode();
+    }
+
+    EnterUserCodeRTTI(Interpreter& interp): EnterUserCodeRTTI(interp.getCallbacks())
+    {}
+
+    ~EnterUserCodeRTTI() {
+      if (fCallbacks)
+        fCallbacks->ReturnedFromUserCode();
+    }
+  };
+}
+
+#endif // CLING_BACKENDPASSES_H