C++-ify varobj iteration

This changes the varobj iteration code to use a C++ class rather than
a C struct with a separate "ops" structure.  The only implementation
is updated to use inheritance.  This simplifies the code quite nicely.

gdb/ChangeLog
2020-12-11  Tom Tromey  <tom@tromey.com>

	* varobj.c (update_dynamic_varobj_children, install_visualizer)
	(varobj::~varobj): Update.
	* varobj-iter.h (struct varobj_iter): Change to interface class.
	(struct varobj_iter_ops): Remove.
	(varobj_iter_next, varobj_iter_delete): Remove.
	* python/py-varobj.c (struct py_varobj_iter): Derive from
	varobj_iter.  Add constructor, destructor.  Rename members.
	(py_varobj_iter::~py_varobj_iter): Rename from
	py_varobj_iter_dtor.
	(py_varobj_iter::next): Rename from py_varobj_iter_next.
	(py_varobj_iter_ops): Remove.
	(py_varobj_iter): Rename from py_varobj_iter_ctor.
	(py_varobj_iter_new): Remove.
	(py_varobj_get_iterator): Update.

1 files changed, 3 insertions, 38 deletions

diff --git a/gdb/varobj-iter.h b/gdb/varobj-iter.h
index 240b686..ed65419 100644
--- a/gdb/varobj-iter.h
+++ b/gdb/varobj-iter.h
@@ -28,50 +28,15 @@ struct varobj_item
   struct value *value;
 };
 
-struct varobj_iter_ops;
-
 /* A dynamic varobj iterator "class".  */
 
 struct varobj_iter
 {
-  /* The 'vtable'.  */
-  const struct varobj_iter_ops *ops;
-
-  /* The varobj this iterator is listing children for.  */
-  struct varobj *var;
-
-  /* The next raw index we will try to check is available.  If it is
-     equal to number_of_children, then we've already iterated the
-     whole set.  */
-  int next_raw_index;
-};
-
-/* The vtable of the varobj iterator class.  */
+public:
 
-struct varobj_iter_ops
-{
-  /* Destructor.  Releases everything from SELF (but not SELF
-     itself).  */
-  void (*dtor) (struct varobj_iter *self);
+  virtual ~varobj_iter () = default;
 
-  /* Returns the next object or NULL if it has reached the end.  */
-  varobj_item *(*next) (struct varobj_iter *self);
+  virtual varobj_item *next () = 0;
 };
 
-/* Returns the next varobj or NULL if it has reached the end.  */
-
-#define varobj_iter_next(ITER)	(ITER)->ops->next (ITER)
-
-/* Delete a varobj_iter object.  */
-
-#define varobj_iter_delete(ITER)	       \
-  do					       \
-    {					       \
-      if ((ITER) != NULL)		       \
-	{				       \
-	  (ITER)->ops->dtor (ITER);	       \
-	  xfree (ITER);		       \
-	}				       \
-    } while (0)
-
 #endif /* VAROBJ_ITER_H */