refactor(core): Combine `is_` and `cast_` event functions.

* Use a single `as_foo` generated function to conditionally
  return a certain event type from a generic `zmk_event_t*`
  pointer.

app/include/zmk/event_manager.h

@@ -39,8 +39,7 @@ struct zmk_event_subscription {
         struct event_type data;                                                                    \
     };                                                                                             \
     struct event_type##_event *new_##event_type(struct event_type);                                \
-    bool is_##event_type(const zmk_event_t *eh);                                                   \
-    struct event_type *cast_##event_type(const zmk_event_t *eh);                                   \
+    struct event_type *as_##event_type(const zmk_event_t *eh);                                     \
     extern const struct zmk_event_type zmk_event_##event_type;
 
 #define ZMK_EVENT_IMPL(event_type)                                                                 \
@@ -54,9 +53,9 @@ struct zmk_event_subscription {
         ev->data = data;                                                                           \
         return ev;                                                                                 \
     };                                                                                             \
-    bool is_##event_type(const zmk_event_t *eh) { return eh->event == &zmk_event_##event_type; };  \
-    struct event_type *cast_##event_type(const zmk_event_t *eh) {                                  \
-        return &((struct event_type##_event *)eh)->data;                                           \
+    struct event_type *as_##event_type(const zmk_event_t *eh) {                                    \
+        return (eh->event == &zmk_event_##event_type) ? &((struct event_type##_event *)eh)->data   \
+                                                      : NULL;                                      \
     };
 
 #define ZMK_LISTENER(mod, cb) const struct zmk_listener zmk_listener_##mod = {.callback = cb};

app/src/behaviors/behavior_hold_tap.c

@@ -88,10 +88,11 @@ static struct zmk_position_state_changed *find_captured_keydown_event(uint32_t p
         if (eh == NULL) {
             return last_match;
         }
-        if (!is_zmk_position_state_changed(eh)) {
+        struct zmk_position_state_changed *position_event = as_zmk_position_state_changed(eh);
+        if (position_event == NULL) {
             continue;
         }
-        struct zmk_position_state_changed *position_event = cast_zmk_position_state_changed(eh);
+
         if (position_event->position == position && position_event->state) {
             last_match = position_event;
         }
@@ -140,14 +141,13 @@ static void release_captured_events() {
         if (undecided_hold_tap != NULL) {
             k_msleep(10);
         }
-        if (is_zmk_position_state_changed(captured_event)) {
-            struct zmk_position_state_changed *position_event =
-                cast_zmk_position_state_changed(captured_event);
+
+        struct zmk_position_state_changed *position_event;
+        struct zmk_keycode_state_changed *modifier_event;
+        if ((position_event = as_zmk_position_state_changed(captured_event)) != NULL) {
             LOG_DBG("Releasing key position event for position %d %s", position_event->position,
                     (position_event->state ? "pressed" : "released"));
-        } else {
-            struct zmk_keycode_state_changed *modifier_event =
-                cast_zmk_keycode_state_changed(captured_event);
+        } else if ((modifier_event = as_zmk_keycode_state_changed(captured_event)) != NULL) {
             LOG_DBG("Releasing mods changed event 0x%02X %s", modifier_event->keycode,
                     (modifier_event->state ? "pressed" : "released"));
         }
@@ -388,7 +388,7 @@ static const struct behavior_driver_api behavior_hold_tap_driver_api = {
 };
 
 static int position_state_changed_listener(const zmk_event_t *eh) {
-    struct zmk_position_state_changed *ev = cast_zmk_position_state_changed(eh);
+    struct zmk_position_state_changed *ev = as_zmk_position_state_changed(eh);
 
     if (undecided_hold_tap == NULL) {
         LOG_DBG("%d bubble (no undecided hold_tap active)", ev->position);
@@ -435,7 +435,7 @@ static inline bool only_mods(struct zmk_keycode_state_changed *ev) {
 
 static int keycode_state_changed_listener(const zmk_event_t *eh) {
     // we want to catch layer-up events too... how?
-    struct zmk_keycode_state_changed *ev = cast_zmk_keycode_state_changed(eh);
+    struct zmk_keycode_state_changed *ev = as_zmk_keycode_state_changed(eh);
 
     if (undecided_hold_tap == NULL) {
         // LOG_DBG("0x%02X bubble (no undecided hold_tap active)", ev->keycode);
@@ -456,9 +456,9 @@ static int keycode_state_changed_listener(const zmk_event_t *eh) {
 }
 
 int behavior_hold_tap_listener(const zmk_event_t *eh) {
-    if (is_zmk_position_state_changed(eh)) {
+    if (as_zmk_position_state_changed(eh) != NULL) {
         return position_state_changed_listener(eh);
-    } else if (is_zmk_keycode_state_changed(eh)) {
+    } else if (as_zmk_keycode_state_changed(eh) != NULL) {
         return keycode_state_changed_listener(eh);
     }
     return ZMK_EV_EVENT_BUBBLE;

app/src/behaviors/behavior_sticky_key.c

@@ -176,10 +176,10 @@ static const struct behavior_driver_api behavior_sticky_key_driver_api = {
 };
 
 static int sticky_key_keycode_state_changed_listener(const zmk_event_t *eh) {
-    if (!is_zmk_keycode_state_changed(eh)) {
+    struct zmk_keycode_state_changed *ev = as_zmk_keycode_state_changed(eh);
+    if (ev == NULL) {
         return ZMK_EV_EVENT_BUBBLE;
     }
-    struct zmk_keycode_state_changed *ev = cast_zmk_keycode_state_changed(eh);
     for (int i = 0; i < ZMK_BHV_STICKY_KEY_MAX_HELD; i++) {
         struct active_sticky_key *sticky_key = &active_sticky_keys[i];
         if (sticky_key->position == ZMK_BHV_STICKY_KEY_POSITION_FREE) {

app/src/combo.c

@@ -291,7 +291,7 @@ static void activate_combo(struct combo_cfg *combo) {
     }
     move_pressed_keys_to_active_combo(active_combo);
     press_combo_behavior(
-        combo, cast_zmk_position_state_changed(active_combo->key_positions_pressed[0])->timestamp);
+        combo, as_zmk_position_state_changed(active_combo->key_positions_pressed[0])->timestamp);
 }
 
 static void deactivate_combo(int active_combo_index) {
@@ -315,7 +315,7 @@ static bool release_combo_key(int32_t position, int64_t timestamp) {
         for (int i = 0; i < active_combo->combo->key_position_len; i++) {
             if (active_combo->key_positions_pressed[i] == NULL) {
                 all_keys_pressed = false;
-            } else if (cast_zmk_position_state_changed(active_combo->key_positions_pressed[i])
+            } else if (as_zmk_position_state_changed(active_combo->key_positions_pressed[i])
                            ->position != position) {
                 all_keys_released = false;
             } else { // not null and position matches
@@ -418,11 +418,11 @@ static void combo_timeout_handler(struct k_work *item) {
 }
 
 static int position_state_changed_listener(const zmk_event_t *ev) {
-    if (!is_zmk_position_state_changed(ev)) {
+    struct zmk_position_state_changed *data = as_zmk_position_state_changed(ev);
+    if (data == NULL) {
         return 0;
     }
 
-    struct zmk_position_state_changed *data = cast_zmk_position_state_changed(ev);
     if (data->state) { // keydown
         return position_state_down(ev, data);
     } else { // keyup

app/src/display/main.c

@@ -76,7 +76,11 @@ int zmk_display_init() {
 }
 
 int display_event_handler(const zmk_event_t *eh) {
-    struct zmk_activity_state_changed *ev = cast_zmk_activity_state_changed(eh);
+    struct zmk_activity_state_changed *ev = as_zmk_activity_state_changed(eh);
+    if (ev == NULL) {
+        return -ENOTSUP;
+    }
+
     switch (ev->state) {
     case ZMK_ACTIVITY_ACTIVE:
         start_display_updates();

app/src/hid_listener.c

@@ -71,8 +71,8 @@ static int hid_listener_keycode_released(uint16_t usage_page, uint32_t keycode,
 }
 
 int hid_listener(const zmk_event_t *eh) {
-    if (is_zmk_keycode_state_changed(eh)) {
-        const struct zmk_keycode_state_changed *ev = cast_zmk_keycode_state_changed(eh);
+    const struct zmk_keycode_state_changed *ev = as_zmk_keycode_state_changed(eh);
+    if (ev) {
         if (ev->state) {
             hid_listener_keycode_pressed(ev->usage_page, ev->keycode, ev->implicit_modifiers);
         } else {

app/src/keymap.c

@@ -247,15 +247,19 @@ int zmk_keymap_sensor_triggered(uint8_t sensor_number, const struct device *sens
 #endif /* ZMK_KEYMAP_HAS_SENSORS */
 
 int keymap_listener(const zmk_event_t *eh) {
-    if (is_zmk_position_state_changed(eh)) {
-        const struct zmk_position_state_changed *ev = cast_zmk_position_state_changed(eh);
-        return zmk_keymap_position_state_changed(ev->position, ev->state, ev->timestamp);
+    const struct zmk_position_state_changed *pos_ev;
+    if ((pos_ev = as_zmk_position_state_changed(eh)) != NULL) {
+        return zmk_keymap_position_state_changed(pos_ev->position, pos_ev->state,
+                                                 pos_ev->timestamp);
+    }
+
 #if ZMK_KEYMAP_HAS_SENSORS
-    } else if (is_zmk_sensor_event(eh)) {
-        const struct zmk_sensor_event *ev = cast_zmk_sensor_event(eh);
-        return zmk_keymap_sensor_triggered(ev->sensor_number, ev->sensor, ev->timestamp);
-#endif /* ZMK_KEYMAP_HAS_SENSORS */
+    const struct zmk_sensor_event *sensor_ev;
+    if ((sensor_ev = as_zmk_sensor_event(eh)) != NULL) {
+        return zmk_keymap_sensor_triggered(sensor_ev->sensor_number, sensor_ev->sensor,
+                                           sensor_ev->timestamp);
     }
+#endif /* ZMK_KEYMAP_HAS_SENSORS */
 
     return -ENOTSUP;
 }

app/src/split_listener.c

@@ -21,8 +21,8 @@ LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
 int split_listener(const zmk_event_t *eh) {
     LOG_DBG("");
-    if (is_zmk_position_state_changed(eh)) {
-        const struct zmk_position_state_changed *ev = cast_zmk_position_state_changed(eh);
+    const struct zmk_position_state_changed *ev = as_zmk_position_state_changed(eh);
+    if (ev != NULL) {
         if (ev->state) {
             return zmk_split_bt_position_pressed(ev->position);
         } else {