[gtk/wip/ebassi/shortcut: 898/900] Add definition macro for internal types

[Emmanuele Bassi <ebassi src gnome org>]

commit c8a85ac3acaee9479a13caf97543bf4b5276bbb3
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Thu Mar 19 15:53:35 2020 +0000

    Add definition macro for internal types
    
    GTK defines various types that are meant to be derivable only within GTK
    itself, and "final" from the perspective of consumers of the GTK API.
    The existing macros defined by GObject, such as G_DECLARE_FINAL_TYPE and
    G_DECLARE_DERIVABLE_TYPE, lack this functionality.
    
    While we wait for GObject to get this kind of macro, we should define
    our own.

 gdk/gdktypes.h | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
---
diff --git a/gdk/gdktypes.h b/gdk/gdktypes.h
index 7eb74b080f..68f8a8b344 100644
--- a/gdk/gdktypes.h
+++ b/gdk/gdktypes.h
@@ -622,6 +622,45 @@ typedef enum
  */
 #define GDK_ACTION_ALL (GDK_ACTION_COPY | GDK_ACTION_MOVE | GDK_ACTION_LINK)
 
+/*
+ * GDK_DECLARE_INTERNAL_TYPE:
+ * @ModuleObjName: The name of the new type, in camel case (like GtkWidget)
+ * @module_obj_name: The name of the new type in lowercase, with words
+ *  separated by '_' (like 'gtk_widget')
+ * @MODULE: The name of the module, in all caps (like 'GTK')
+ * @OBJ_NAME: The bare name of the type, in all caps (like 'WIDGET')
+ * @ParentName: the name of the parent type, in camel case (like GtkWidget)
+ *
+ * A convenience macro for emitting the usual declarations in the
+ * header file for a type which is intended to be subclassed only
+ * by internal consumers.
+ *
+ * This macro differs from %G_DECLARE_DERIVABLE_TYPE and %G_DECLARE_FINAL_TYPE
+ * by declaring a type that is only derivable internally. Internal users can
+ * derive this type, assuming they have access to the instance and class
+ * structures; external users will not be able to subclass this type.
+ */
+#define GDK_DECLARE_INTERNAL_TYPE(ModuleObjName, module_obj_name, MODULE, OBJ_NAME, ParentName) \
+  GType module_obj_name##_get_type (void);                                                               \
+  G_GNUC_BEGIN_IGNORE_DEPRECATIONS                                                                       \
+  typedef struct _##ModuleObjName ModuleObjName;                                                         \
+  typedef struct _##ModuleObjName##Class ModuleObjName##Class;                                           \
+                                                                                                         \
+  _GLIB_DEFINE_AUTOPTR_CHAINUP (ModuleObjName, ParentName)                                               \
+  G_DEFINE_AUTOPTR_CLEANUP_FUNC (ModuleObjName##Class, g_type_class_unref)                               \
+                                                                                                         \
+  G_GNUC_UNUSED static inline ModuleObjName * MODULE##_##OBJ_NAME (gpointer ptr) {                       \
+    return G_TYPE_CHECK_INSTANCE_CAST (ptr, module_obj_name##_get_type (), ModuleObjName); }             \
+  G_GNUC_UNUSED static inline ModuleObjName##Class * MODULE##_##OBJ_NAME##_CLASS (gpointer ptr) {        \
+    return G_TYPE_CHECK_CLASS_CAST (ptr, module_obj_name##_get_type (), ModuleObjName##Class); }         \
+  G_GNUC_UNUSED static inline gboolean MODULE##_IS_##OBJ_NAME (gpointer ptr) {                           \
+    return G_TYPE_CHECK_INSTANCE_TYPE (ptr, module_obj_name##_get_type ()); }                            \
+  G_GNUC_UNUSED static inline gboolean MODULE##_IS_##OBJ_NAME##_CLASS (gpointer ptr) {                   \
+    return G_TYPE_CHECK_CLASS_TYPE (ptr, module_obj_name##_get_type ()); }                               \
+  G_GNUC_UNUSED static inline ModuleObjName##Class * MODULE##_##OBJ_NAME##_GET_CLASS (gpointer ptr) {    \
+    return G_TYPE_INSTANCE_GET_CLASS (ptr, module_obj_name##_get_type (), ModuleObjName##Class); }       \
+  G_GNUC_END_IGNORE_DEPRECATIONS
+
 G_END_DECLS
 
 #endif /* __GDK_TYPES_H__ */