luaclass: add inheritance support

Signed-off-by: Julien Danjou <julien@danjou.info>

common/luaclass.c

@@ -48,16 +48,22 @@ void *
 luaA_toudata(lua_State *L, int ud, lua_class_t *class)
 {
     void *p = lua_touserdata(L, ud);
-    if(p) /* value is a userdata? */
+    if(p && lua_getmetatable(L, ud)) /* does it have a metatable? */
-        if(lua_getmetatable(L, ud)) /* does it have a metatable? */
     {
-            lua_pushlightuserdata(L, class);
+        /* Get the lua_class_t that matches this metatable */
         lua_rawget(L, LUA_REGISTRYINDEX);
-            if(!lua_rawequal(L, -1, -2)) /* does it have the correct mt? */
+        lua_class_t *metatable_class = lua_touserdata(L, -1);
-                p = NULL;
+
-            lua_pop(L, 2); /* remove both metatables */
+        /* remove lightuserdata (lua_class pointer) */
-        }
+        lua_pop(L, 1);
+
+        /* Now, check that the class given in argument is the same as the
+         * metatable's object, or one of its parent (inheritance) */
+        for(; metatable_class; metatable_class = metatable_class->parent)
+            if(metatable_class == class)
                 return p;
+    }
+    return NULL;
 }
 
 /** Check for a udata class.
@@ -85,10 +91,14 @@ luaA_class_get(lua_State *L, int idx)
 {
     int type = lua_type(L, idx);
 
-    if(type == LUA_TUSERDATA)
+    if(type == LUA_TUSERDATA && lua_getmetatable(L, idx))
-        foreach(class, luaA_classes)
+    {
-            if(luaA_toudata(L, idx, *class))
+        /* Use the metatable has key to get the class from registry */
-                return *class;
+        lua_rawget(L, LUA_REGISTRYINDEX);
+        lua_class_t *class = lua_touserdata(L, -1);
+        lua_pop(L, 1);
+        return class;
+    }
 
     return NULL;
 }
@@ -153,9 +163,23 @@ luaA_class_add_property(lua_class_t *lua_class,
                                     });
 }
 
+/** Setup a new Lua class.
+ * \param L The Lua VM state.
+ * \param name The class name.
+ * \param parent The parent class (inheritance).
+ * \param allocator The allocator function used when creating a new object.
+ * \param checker The check function to call when using luaA_checkudata().
+ * \param index_miss_property Function to call when an object of this class
+ * receive a __index request on an unknown property.
+ * \param newindex_miss_property Function to call when an object of this class
+ * receive a __newindex request on an unknown property.
+ * \param methods The methods to set on the class table.
+ * \param meta The meta-methods to set on the class objects.
+ */
 void
 luaA_class_setup(lua_State *L, lua_class_t *class,
                  const char *name,
+                 lua_class_t *parent,
                  lua_class_allocator_t allocator,
                  lua_class_checker_t checker,
                  lua_class_propfunc_t index_miss_property,
@@ -165,11 +189,17 @@ luaA_class_setup(lua_State *L, lua_class_t *class,
 {
     /* Create the metatable */
     lua_newtable(L);
-    /* Register it with class pointer as key in the registry */
+    /* Register it with class pointer as key in the registry
+     * class-pointer -> metatable */
     lua_pushlightuserdata(L, class);
     /* Duplicate the metatable */
     lua_pushvalue(L, -2);
     lua_rawset(L, LUA_REGISTRYINDEX);
+    /* Now register class pointer with metatable as key in the registry
+     * metatable -> class-pointer */
+    lua_pushvalue(L, -1);
+    lua_pushlightuserdata(L, class);
+    lua_rawset(L, LUA_REGISTRYINDEX);
 
     lua_pushvalue(L, -1);           /* dup metatable                      2 */
     lua_setfield(L, -2, "__index"); /* metatable.__index = metatable      1 */
@@ -185,6 +215,7 @@ luaA_class_setup(lua_State *L, lua_class_t *class,
     class->index_miss_property = index_miss_property;
     class->newindex_miss_property = newindex_miss_property;
     class->checker = checker;
+    class->parent = parent;
 
     lua_class_array_append(&luaA_classes, class);
 }
@@ -224,20 +255,28 @@ luaA_class_emit_signal(lua_State *L, lua_class_t *lua_class,
 int
 luaA_usemetatable(lua_State *L, int idxobj, int idxfield)
 {
-    /* Get metatable of the object. */
+    lua_class_t *class = luaA_class_get(L, idxobj);
-    lua_getmetatable(L, idxobj);
+
-    /* Get the field */
+    for(; class; class = class->parent)
+    {
+        /* Push the class */
+        lua_pushlightuserdata(L, class);
+        /* Get its metatable from registry */
+        lua_rawget(L, LUA_REGISTRYINDEX);
+        /* Push the field */
         lua_pushvalue(L, idxfield);
+        /* Get the field in the metatable */
         lua_rawget(L, -2);
         /* Do we have a field like that? */
         if(!lua_isnil(L, -1))
         {
-        /* Yes, so return it! */
+            /* Yes, so remove the metatable and return it! */
             lua_remove(L, -2);
             return 1;
         }
-    /* No, so remove everything. */
+        /* No, so remove the metatable and its value */
         lua_pop(L, 2);
+    }
 
     return 0;
 }
@@ -264,7 +303,17 @@ luaA_class_property_get(lua_State *L, lua_class_t *lua_class, int fieldidx)
     const char *attr = luaL_checklstring(L, fieldidx, &len);
     awesome_token_t token = a_tokenize(attr, len);
 
-    return lua_class_property_array_getbyid(&lua_class->properties, token);
+    /* Look for the property in the class; if not found, go in the parent class. */
+    for(; lua_class; lua_class = lua_class->parent)
+    {
+        lua_class_property_t *prop =
+            lua_class_property_array_getbyid(&lua_class->properties, token);
+
+        if(prop)
+            return prop;
+    }
+
+    return NULL;
 }
 
 /** Generic index meta function for objects.
@@ -350,12 +399,7 @@ luaA_class_new(lua_State *L, lua_class_t *lua_class)
          * number TO A STRING, confusing lua_next() */
         if(lua_isstring(L, -2))
         {
-            /* Lookup the property using token */
+            lua_class_property_t *prop = luaA_class_property_get(L, lua_class, -2);
-            size_t len;
-            const char *attr = lua_tolstring(L, -2, &len);
-            lua_class_property_t *prop =
-                lua_class_property_array_getbyid(&lua_class->properties,
-                                                 a_tokenize(attr, len));
 
             if(prop && prop->new)
                 prop->new(L, object);

common/luaclass.h

@@ -46,12 +46,15 @@ typedef int (*lua_class_propfunc_t)(lua_State *, lua_object_t *);
 
 typedef bool (*lua_class_checker_t)(lua_object_t *);
 
-typedef struct
+typedef struct lua_class_t lua_class_t;
+struct lua_class_t
 {
     /** Class name */
     const char *name;
     /** Class signals */
     signal_array_t signals;
+    /** Parent class */
+    lua_class_t *parent;
     /** Allocator for creating new objects of that class */
     lua_class_allocator_t allocator;
     /** Class properties */
@@ -62,7 +65,7 @@ typedef struct
     lua_class_propfunc_t newindex_miss_property;
     /** Function to call to check if an object is valid */
     lua_class_checker_t checker;
-} lua_class_t;
+};
 
 const char * luaA_typename(lua_State *, int);
 lua_class_t * luaA_class_get(lua_State *, int);
@@ -72,7 +75,8 @@ void luaA_class_remove_signal(lua_State *, lua_class_t *, const char *, int);
 void luaA_class_emit_signal(lua_State *, lua_class_t *, const char *, int);
 
 void luaA_openlib(lua_State *, const char *, const struct luaL_reg[], const struct luaL_reg[]);
-void luaA_class_setup(lua_State *, lua_class_t *, const char *, lua_class_allocator_t, lua_class_checker_t,
+void luaA_class_setup(lua_State *, lua_class_t *, const char *, lua_class_t *,
+                      lua_class_allocator_t, lua_class_checker_t,
                       lua_class_propfunc_t, lua_class_propfunc_t,
                       const struct luaL_reg[], const struct luaL_reg[]);
 

common/luaobject.c

@@ -279,7 +279,24 @@ int
 luaA_object_tostring(lua_State *L)
 {
     lua_class_t *lua_class = luaA_class_get(L, 1);
-    lua_pushfstring(L, "%s: %p", lua_class->name, luaA_checkudata(L, 1, lua_class));
+    lua_object_t *object = luaA_checkudata(L, 1, lua_class);
+
+    int i = 0;
+    for(; lua_class; lua_class = lua_class->parent, i++)
+    {
+        if(i)
+        {
+            lua_pushliteral(L, "/");
+            lua_insert(L, - (i * 2));
+        }
+        lua_pushstring(L, NONULL(lua_class->name));
+        lua_insert(L, - (i * 2) - 1);
+    }
+
+    lua_pushfstring(L, ": %p", object);
+
+    lua_concat(L, i * 2);
+
     return 1;
 }
 

objects/button.c

@@ -114,7 +114,8 @@ button_class_setup(lua_State *L)
         { NULL, NULL }
     };
 
-    luaA_class_setup(L, &button_class, "button", (lua_class_allocator_t) button_new, NULL,
+    luaA_class_setup(L, &button_class, "button", NULL,
+                     (lua_class_allocator_t) button_new, NULL,
                      luaA_class_index_miss_property, luaA_class_newindex_miss_property,
                      button_methods, button_meta);
     luaA_class_add_property(&button_class, A_TK_BUTTON,

objects/client.c

@@ -2089,7 +2089,8 @@ client_class_setup(lua_State *L)
         { NULL, NULL }
     };
 
-    luaA_class_setup(L, &client_class, "client", (lua_class_allocator_t) client_new,
+    luaA_class_setup(L, &client_class, "client", NULL,
+                     (lua_class_allocator_t) client_new,
                      (lua_class_checker_t) client_checker,
                      luaA_class_index_miss_property, luaA_class_newindex_miss_property,
                      client_methods, client_meta);

objects/image.c

@@ -820,7 +820,8 @@ image_class_setup(lua_State *L)
         { NULL, NULL }
     };
 
-    luaA_class_setup(L, &image_class, "image", (lua_class_allocator_t) image_new, NULL,
+    luaA_class_setup(L, &image_class, "image", NULL,
+                     (lua_class_allocator_t) image_new, NULL,
                      luaA_class_index_miss_property, luaA_class_newindex_miss_property,
                      image_methods, image_meta);
     luaA_class_add_property(&image_class, A_TK_WIDTH,

objects/key.c

@@ -1126,7 +1126,8 @@ key_class_setup(lua_State *L)
         { NULL, NULL },
     };
 
-    luaA_class_setup(L, &key_class, "key", (lua_class_allocator_t) key_new, NULL,
+    luaA_class_setup(L, &key_class, "key", NULL,
+                     (lua_class_allocator_t) key_new, NULL,
                      luaA_class_index_miss_property, luaA_class_newindex_miss_property,
                      key_methods, key_meta);
     luaA_class_add_property(&key_class, A_TK_KEY,

objects/tag.c

@@ -417,7 +417,8 @@ tag_class_setup(lua_State *L)
         { NULL, NULL },
     };
 
-    luaA_class_setup(L, &tag_class, "tag", (lua_class_allocator_t) tag_new, NULL,
+    luaA_class_setup(L, &tag_class, "tag", NULL,
+                     (lua_class_allocator_t) tag_new, NULL,
                      luaA_class_index_miss_property, luaA_class_newindex_miss_property,
                      tag_methods, tag_meta);
     luaA_class_add_property(&tag_class, A_TK_NAME,

objects/timer.c

@@ -122,7 +122,8 @@ timer_class_setup(lua_State *L)
             { NULL, NULL },
     };
 
-    luaA_class_setup(L, &timer_class, "timer", (lua_class_allocator_t) timer_new, NULL,
+    luaA_class_setup(L, &timer_class, "timer", NULL,
+                     (lua_class_allocator_t) timer_new, NULL,
                      luaA_class_index_miss_property, luaA_class_newindex_miss_property,
                      timer_methods, timer_meta);
     luaA_class_add_property(&timer_class, A_TK_TIMEOUT,

objects/wibox.c

@@ -1389,7 +1389,8 @@ wibox_class_setup(lua_State *L)
         { NULL, NULL },
     };
 
-    luaA_class_setup(L, &wibox_class, "wibox", (lua_class_allocator_t) wibox_new, NULL,
+    luaA_class_setup(L, &wibox_class, "wibox", NULL,
+                     (lua_class_allocator_t) wibox_new, NULL,
                      luaA_class_index_miss_property, luaA_class_newindex_miss_property,
                      wibox_methods, wibox_meta);
     luaA_class_add_property(&wibox_class, A_TK_WIDGETS,

objects/widget.c

@@ -578,7 +578,8 @@ widget_class_setup(lua_State *L)
         { NULL, NULL }
     };
 
-    luaA_class_setup(L, &widget_class, "widget", (lua_class_allocator_t) widget_new, NULL,
+    luaA_class_setup(L, &widget_class, "widget", NULL,
+                     (lua_class_allocator_t) widget_new, NULL,
                      NULL, NULL,
                      widget_methods, widget_meta);
     luaA_class_add_property(&widget_class, A_TK_VISIBLE,

screen.c

@@ -507,8 +507,20 @@ luaA_screen_index(lua_State *L)
     const char *buf;
     screen_t *s;
 
-    if(luaA_usemetatable(L, 1, 2))
+    /* Get metatable of the screen. */
+    lua_getmetatable(L, 1);
+    /* Get the field */
+    lua_pushvalue(L, 2);
+    lua_rawget(L, -2);
+    /* Do we have a field like that? */
+    if(!lua_isnil(L, -1))
+    {
+        /* Yes, so return it! */
+        lua_remove(L, -2);
         return 1;
+    }
+    /* No, so remove everything. */
+    lua_pop(L, 2);
 
     buf = luaL_checklstring(L, 2, &len);
     s = lua_touserdata(L, 1);