+#include <assert.h>
+#include <libpspp/cast.h>
+
+extern const struct chart_item_class piechart_class;
+
+/* Returns true if SUPER is a piechart, otherwise false. */
+static inline bool
+is_piechart (const struct chart_item *super)
+{
+ return super->class == &piechart_class;
+}
+
+/* Returns SUPER converted to piechart. SUPER must be a piechart, as
+ reported by is_piechart. */
+static inline struct piechart *
+to_piechart (const struct chart_item *super)
+{
+ assert (is_piechart (super));
+ return UP_CAST (super, struct piechart, chart_item);
+}
+
+/* Returns INSTANCE converted to chart_item. */
+static inline struct chart_item *
+piechart_super (const struct piechart *instance)
+{
+ return CONST_CAST (struct chart_item *, &instance->chart_item);
+}
+
+/* Increments INSTANCE's reference count and returns INSTANCE. */
+static inline struct piechart *
+piechart_ref (const struct piechart *instance)
+{
+ return to_piechart (chart_item_ref (&instance->chart_item));
+}
+
+/* Decrements INSTANCE's reference count, then destroys INSTANCE if
+ the reference count is now zero. */
+static inline void
+piechart_unref (struct piechart *instance)
+{
+ chart_item_unref (&instance->chart_item);
+}
+
+/* Returns true if INSTANCE's reference count is greater than 1,
+ false otherwise. */
+static inline bool
+piechart_is_shared (const struct piechart *instance)
+{
+ return chart_item_is_shared (&instance->chart_item);
+}
+
+static inline void
+piechart_submit (struct piechart *instance)
+{
+ chart_item_submit (&instance->chart_item);
+}
+\f
+#endif /* output/charts/piechart.h */