New python event "clear_objfiles".

If one is watching new_objfile events in python, it helps to know
when the list of objfiles is cleared.  This patch adds a new
clear_objfiles event to support this.

This patch is all just cut-n-paste-n-tweak derived from
the new_objfiles event.

gdb/ChangeLog:

	* NEWS: Mention new event gdb.clear_objfiles.
	* python/py-event.h (emit_clear_objfiles_event): Clear
	* python/py-events.h (events_object): New member clear_objfiles.
	* python/py-evts.c (gdbpy_initialize_py_events): Add clear_objfiles
	event.
	* python/py-inferior.c (python_new_objfile): If objfile is NULL,
	emit clear_objfiles event.
	* python/py-newobjfileevent.c (create_clear_objfiles_event_object): New
	function.
	(emit_clear_objfiles_event): New function.
	(clear_objfiles): New event.
	* python/python-internal.h (gdbpy_initialize_clear_objfiles_event):
	Declare.
	* python/python.c (_initialize_python): Call
	gdbpy_initialize_clear_objfiles_event.

gdb/doc/ChangeLog:

	* python.texi (Events In Python): Document clear_objfiles event.

gdb/testsuite/ChangeLog:

	* gdb.python/py-events.exp: Update expected output for clear_objfiles
	event.
	* gdb.python/py-events.py: Add clear_objfiles event.

1 files changed, 55 insertions, 0 deletions

diff --git a/gdb/python/py-newobjfileevent.c b/gdb/python/py-newobjfileevent.c
index e4e1351..104ed07 100644
--- a/gdb/python/py-newobjfileevent.c
+++ b/gdb/python/py-newobjfileevent.c
@@ -22,6 +22,8 @@
 
 static PyTypeObject new_objfile_event_object_type
     CPYCHECKER_TYPE_OBJECT_FOR_TYPEDEF ("event_object");
+static PyTypeObject clear_objfiles_event_object_type
+    CPYCHECKER_TYPE_OBJECT_FOR_TYPEDEF ("event_object");
 
 static PyObject *
 create_new_objfile_event_object (struct objfile *objfile)
@@ -72,3 +74,56 @@ GDBPY_NEW_EVENT_TYPE (new_objfile,
                       "GDB new object file event object",
                       event_object_type,
                       static);
+
+/* Subroutine of emit_clear_objfiles_event to simplify it.  */
+
+static PyObject *
+create_clear_objfiles_event_object (void)
+{
+  PyObject *objfile_event;
+  PyObject *py_progspace;
+
+  objfile_event = create_event_object (&clear_objfiles_event_object_type);
+  if (!objfile_event)
+    goto fail;
+
+  /* Note that pspace_to_pspace_object returns a borrowed reference,
+     so we don't need a decref here.  */
+  py_progspace = pspace_to_pspace_object (current_program_space);
+  if (!py_progspace || evpy_add_attribute (objfile_event,
+					   "progspace",
+					   py_progspace) < 0)
+    goto fail;
+
+  return objfile_event;
+
+ fail:
+  Py_XDECREF (objfile_event);
+  return NULL;
+}
+
+/* Callback function which notifies observers when the "clear objfiles"
+   event occurs.
+   This function will create a new Python clear_objfiles event object.
+   Return -1 if emit fails.  */
+
+int
+emit_clear_objfiles_event (void)
+{
+  PyObject *event;
+
+  if (evregpy_no_listeners_p (gdb_py_events.clear_objfiles))
+    return 0;
+
+  event = create_clear_objfiles_event_object ();
+  if (event)
+    return evpy_emit_event (event, gdb_py_events.clear_objfiles);
+  return -1;
+}
+
+GDBPY_NEW_EVENT_TYPE (clear_objfiles,
+		      "gdb.ClearObjFilesEvent",
+		      "ClearObjFilesEvent",
+		      "GDB clear object files event object",
+		      event_object_type,
+		      static);