--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libinterp/interpfcn/octave-link.cc	Wed Apr 03 23:16:37 2013 -0400
@@ -0,0 +1,168 @@
+/*
+
+Copyright (C) 2013 John W. Eaton
+Copyright (C) 2011-2012 Jacob Dawid
+Copyright (C) 2011-2012 John P. Swensen
+
+This file is part of Octave.
+
+Octave is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 3 of the License, or (at your
+option) any later version.
+
+Octave is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with Octave; see the file COPYING.  If not, see
+<http://www.gnu.org/licenses/>.
+
+*/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "cmd-edit.h"
+#include "defun.h"
+#include "oct-env.h"
+#include "oct-mutex.h"
+#include "singleton-cleanup.h"
+#include "symtab.h"
+#include "toplev.h"
+
+#include "octave-link.h"
+
+static int
+octave_readline_hook (void)
+{
+  octave_link::entered_readline_hook ();
+  octave_link::generate_events ();
+  octave_link::process_events ();
+  octave_link::finished_readline_hook ();
+
+  return 0;
+}
+
+static void
+octave_exit_hook (int)
+{
+  octave_link::about_to_exit ();
+}
+
+octave_link *octave_link::instance = 0;
+
+octave_link::octave_link (void)
+  : event_listener (0), event_queue_mutex (new octave_mutex ()),
+    gui_event_queue (), last_cwd (), debugging (false)
+{
+  command_editor::add_event_hook (octave_readline_hook);
+
+  octave_exit = octave_exit_hook;
+}
+
+// OBJ should be a new object of a class that is derived from
+// the base class octave_link.  It will be cleaned up by octave_link.
+
+void
+octave_link::connect (octave_link* obj)
+{
+  if (instance)
+    ::error ("octave_link is already linked!");
+  else
+    instance = obj;
+
+  singleton_cleanup_list::add (cleanup_instance);
+}
+
+void
+octave_link::do_register_event_listener (octave_event_listener *el)
+{
+  event_listener = el;
+}
+
+void
+octave_link::do_generate_events (void)
+{
+  std::string current_working_directory = octave_env::get_current_directory ();
+
+  if (current_working_directory != last_cwd)
+    {
+      last_cwd = current_working_directory;
+
+      if (event_listener)
+        event_listener->current_directory_has_changed (last_cwd);
+    }
+
+  if (debugging != Vdebugging)
+    {
+      debugging = Vdebugging;
+
+      if (event_listener)
+        {
+          if (debugging)
+            event_listener->entered_debug_mode ();
+          else
+            event_listener->quit_debug_mode ();
+        }
+    }
+}
+
+void
+octave_link::do_process_events (void)
+{
+  event_queue_mutex->lock ();
+
+  gui_event_queue.run ();
+
+  event_queue_mutex->unlock ();
+}
+
+void
+octave_link::do_about_to_exit (void)
+{
+  event_queue_mutex->lock ();
+
+  gui_event_queue.discard ();
+
+  event_queue_mutex->unlock ();
+
+  if (event_listener)
+    event_listener->about_to_exit ();
+}
+
+std::string
+octave_link::do_last_working_directory (void)
+{
+  return last_cwd;
+}
+
+bool
+octave_link::instance_ok (void)
+{
+  return instance != 0;
+}
+
+DEFUN (__octave_link_edit_file__, args, ,
+  "-*- texinfo -*-\n\
+@deftypefn {Built-in Function} {} __octave_link_edit_file__ (@var{file})\n\
+Undocumented internal function.\n\
+@end deftypefn")
+{
+  octave_value retval;
+
+  if (args.length () == 1)
+    {
+      std::string file = args(0).string_value ();
+
+      if (! error_state)
+        retval = octave_link::edit_file (file);
+      else
+        error ("expecting file name as argument");
+    }
+
+  return retval;
+}