Implement iterators per container type

This introduces the following `for_each` functions:

* root_for_each_workspace
* root_for_each_container
* output_for_each_workspace
* output_for_each_container
* workspace_for_each_container

And introduces the following `find` functions:

* root_find_output
* root_find_workspace
* root_find_container
* output_find_workspace
* output_find_container
* workspace_find_container
* container_find_child

And removes the following functions:

* container_descendants
* container_for_each_descendant
* container_find

This change is preparing the way for demoting sway_container. Eventually
these functions will accept and return sway_outputs, sway_workspaces and
sway_containers (meaning a C_CONTAINER or C_VIEW).

This change also makes it easy to handle abnormalities like the
workspace floating list, root's scratchpad list and (once implemented)
root's saved workspaces list for when there's no connected outputs.

include/sway/output.h

@@ -95,4 +95,16 @@ void output_drag_icons_for_each_surface(struct sway_output *output,
 	struct wl_list *drag_icons, sway_surface_iterator_func_t iterator,
 	void *user_data);
 
+void output_for_each_workspace(struct sway_container *output,
+		void (*f)(struct sway_container *con, void *data), void *data);
+
+void output_for_each_container(struct sway_container *output,
+		void (*f)(struct sway_container *con, void *data), void *data);
+
+struct sway_container *output_find_workspace(struct sway_container *output,
+		bool (*test)(struct sway_container *con, void *data), void *data);
+
+struct sway_container *output_find_container(struct sway_container *output,
+		bool (*test)(struct sway_container *con, void *data), void *data);
+
 #endif

include/sway/tree/container.h

@@ -214,15 +214,11 @@ struct sway_container *container_destroy(struct sway_container *container);
 
 struct sway_container *container_close(struct sway_container *container);
 
-void container_descendants(struct sway_container *root,
-		enum sway_container_type type,
-		void (*func)(struct sway_container *item, void *data), void *data);
-
 /**
  * Search a container's descendants a container based on test criteria. Returns
  * the first container that passes the test.
  */
-struct sway_container *container_find(struct sway_container *container,
+struct sway_container *container_find_child(struct sway_container *container,
 		bool (*test)(struct sway_container *view, void *data), void *data);
 
 /**
@@ -244,10 +240,7 @@ struct sway_container *tiling_container_at(
 		struct sway_container *con, double lx, double ly,
 		struct wlr_surface **surface, double *sx, double *sy);
 
-/**
+void container_for_each_child(struct sway_container *container,
- * Apply the function for each child of the container depth first.
- */
-void container_for_each_descendant(struct sway_container *container,
 		void (*f)(struct sway_container *container, void *data), void *data);
 
 /**

include/sway/tree/root.h

@@ -58,4 +58,19 @@ struct sway_container *root_workspace_for_pid(pid_t pid);
 
 void root_record_workspace_pid(pid_t pid);
 
+void root_for_each_workspace(void (*f)(struct sway_container *con, void *data),
+		void *data);
+
+void root_for_each_container(void (*f)(struct sway_container *con, void *data),
+		void *data);
+
+struct sway_container *root_find_output(
+		bool (*test)(struct sway_container *con, void *data), void *data);
+
+struct sway_container *root_find_workspace(
+		bool (*test)(struct sway_container *con, void *data), void *data);
+
+struct sway_container *root_find_container(
+		bool (*test)(struct sway_container *con, void *data), void *data);
+
 #endif

include/sway/tree/workspace.h

@@ -50,6 +50,12 @@ struct sway_container *workspace_output_get_highest_available(
 
 void workspace_detect_urgent(struct sway_container *workspace);
 
+void workspace_for_each_container(struct sway_container *ws,
+		void (*f)(struct sway_container *con, void *data), void *data);
+
+struct sway_container *workspace_find_container(struct sway_container *ws,
+		bool (*test)(struct sway_container *con, void *data), void *data);
+
 /**
  * Wrap the workspace's tiling children in a new container.
  * The new container will be the only direct tiling child of the workspace.

sway/commands/hide_edge_borders.c

@@ -31,7 +31,7 @@ struct cmd_results *cmd_hide_edge_borders(int argc, char **argv) {
 				"<none|vertical|horizontal|both|smart>'");
 	}
 
-	container_for_each_descendant(&root_container, _configure_view, NULL);
+	root_for_each_container(_configure_view, NULL);
 
 	return cmd_results_new(CMD_SUCCESS, NULL, NULL);
 }

sway/commands/show_marks.c

@@ -24,8 +24,7 @@ struct cmd_results *cmd_show_marks(int argc, char **argv) {
 	config->show_marks = parse_boolean(argv[0], config->show_marks);
 
 	if (config->show_marks) {
-		container_for_each_descendant(&root_container,
+		root_for_each_container(rebuild_marks_iterator, NULL);
-				rebuild_marks_iterator, NULL);
 	}
 
 	for (int i = 0; i < root_container.children->length; ++i) {

sway/commands/swap.c

@@ -50,13 +50,13 @@ struct cmd_results *cmd_swap(int argc, char **argv) {
 	if (strcasecmp(argv[2], "id") == 0) {
 #ifdef HAVE_XWAYLAND
 		xcb_window_t id = strtol(value, NULL, 0);
-		other = container_find(&root_container, test_id, (void *)&id);
+		other = root_find_container(test_id, (void *)&id);
 #endif
 	} else if (strcasecmp(argv[2], "con_id") == 0) {
 		size_t con_id = atoi(value);
-		other = container_find(&root_container, test_con_id, (void *)con_id);
+		other = root_find_container(test_con_id, (void *)con_id);
 	} else if (strcasecmp(argv[2], "mark") == 0) {
-		other = container_find(&root_container, test_mark, (void *)value);
+		other = root_find_container(test_mark, (void *)value);
 	} else {
 		free(value);
 		return cmd_results_new(CMD_INVALID, "swap", EXPECTED_SYNTAX);

sway/commands/unmark.c

@@ -52,8 +52,7 @@ struct cmd_results *cmd_unmark(int argc, char **argv) {
 		view_find_and_unmark(mark);
 	} else {
 		// Remove all marks from all views
-		container_for_each_descendant(&root_container,
+		root_for_each_container(remove_all_marks_iterator, NULL);
-				remove_all_marks_iterator, NULL);
 	}
 	free(mark);
 

sway/config.c

@@ -822,18 +822,7 @@ void config_update_font_height(bool recalculate) {
 	size_t prev_max_height = config->font_height;
 	config->font_height = 0;
 
-	container_for_each_descendant(&root_container,
+	root_for_each_container(find_font_height_iterator, &recalculate);
-			find_font_height_iterator, &recalculate);
-
-	// Also consider floating views
-	for (int i = 0; i < root_container.children->length; ++i) {
-		struct sway_container *output = root_container.children->items[i];
-		for (int j = 0; j < output->children->length; ++j) {
-			struct sway_container *ws = output->children->items[j];
-			container_for_each_descendant(ws->sway_workspace->floating,
-					find_font_height_iterator, &recalculate);
-		}
-	}
 
 	if (config->font_height != prev_max_height) {
 		arrange_windows(&root_container);

sway/criteria.c

@@ -167,8 +167,7 @@ static bool criteria_matches_view(struct criteria *criteria,
 			return false;
 		}
 		list_t *urgent_views = create_list();
-		container_for_each_descendant(&root_container,
+		root_for_each_container(find_urgent_iterator, urgent_views);
-				find_urgent_iterator, urgent_views);
 		list_stable_sort(urgent_views, cmp_urgent);
 		struct sway_view *target;
 		if (criteria->urgent == 'o') { // oldest
@@ -228,17 +227,7 @@ list_t *criteria_get_views(struct criteria *criteria) {
 		.criteria = criteria,
 		.matches = matches,
 	};
-	container_for_each_descendant(&root_container,
+	root_for_each_container(criteria_get_views_iterator, &data);
-		criteria_get_views_iterator, &data);
-
-	// Scratchpad items which are hidden are not in the tree.
-	for (int i = 0; i < root_container.sway_root->scratchpad->length; ++i) {
-		struct sway_container *con =
-			root_container.sway_root->scratchpad->items[i];
-		if (!con->parent) {
-			criteria_get_views_iterator(con, &data);
-		}
-	}
 	return matches;
 }
 

sway/desktop/output.c

@@ -303,15 +303,14 @@ struct send_frame_done_data {
 
 static void send_frame_done_container_iterator(struct sway_container *con,
 		void *_data) {
-	struct send_frame_done_data *data = _data;
+	if (con->type != C_VIEW) {
-	if (!sway_assert(con->type == C_VIEW, "expected a view")) {
 		return;
 	}
-
 	if (!view_is_visible(con->sway_view)) {
 		return;
 	}
 
+	struct send_frame_done_data *data = _data;
 	output_view_for_each_surface(data->output, con->sway_view,
 		send_frame_done_iterator, data->when);
 }
@@ -322,7 +321,7 @@ static void send_frame_done_container(struct sway_output *output,
 		.output = output,
 		.when = when,
 	};
-	container_descendants(con, C_VIEW,
+	output_for_each_container(output->swayc,
 			send_frame_done_container_iterator, &data);
 }
 

sway/input/seat.c

@@ -313,9 +313,6 @@ static void handle_new_drag_icon(struct wl_listener *listener, void *data) {
 
 static void collect_focus_iter(struct sway_container *con, void *data) {
 	struct sway_seat *seat = data;
-	if (con->type > C_WORKSPACE) {
-		return;
-	}
 	struct sway_seat_container *seat_con =
 		seat_container_from_container(seat, con);
 	if (!seat_con) {
@@ -349,7 +346,8 @@ struct sway_seat *seat_create(struct sway_input_manager *input,
 	// init the focus stack
 	wl_list_init(&seat->focus_stack);
 
-	container_for_each_descendant(&root_container, collect_focus_iter, seat);
+	root_for_each_workspace(collect_focus_iter, seat);
+	root_for_each_container(collect_focus_iter, seat);
 
 	wl_signal_add(&root_container.sway_root->events.new_container,
 		&seat->new_container);

sway/ipc-server.c

@@ -522,7 +522,7 @@ void ipc_client_disconnect(struct ipc_client *client) {
 
 static void ipc_get_workspaces_callback(struct sway_container *workspace,
 		void *data) {
-	if (workspace->type != C_WORKSPACE) {
+	if (!sway_assert(workspace->type == C_WORKSPACE, "Expected a workspace")) {
 		return;
 	}
 	json_object *workspace_json = ipc_json_describe_container(workspace);
@@ -631,8 +631,7 @@ void ipc_client_handle_command(struct ipc_client *client) {
 	case IPC_GET_WORKSPACES:
 	{
 		json_object *workspaces = json_object_new_array();
-		container_for_each_descendant(&root_container,
+		root_for_each_workspace(ipc_get_workspaces_callback, workspaces);
-				ipc_get_workspaces_callback, workspaces);
 		const char *json_string = json_object_to_json_string(workspaces);
 		client_valid =
 			ipc_send_reply(client, json_string, (uint32_t)strlen(json_string));
@@ -729,8 +728,7 @@ void ipc_client_handle_command(struct ipc_client *client) {
 	case IPC_GET_MARKS:
 	{
 		json_object *marks = json_object_new_array();
-		container_descendants(&root_container, C_VIEW, ipc_get_marks_callback,
+		root_for_each_container(ipc_get_marks_callback, marks);
-				marks);
 		const char *json_string = json_object_to_json_string(marks);
 		client_valid =
 			ipc_send_reply(client, json_string, (uint32_t)strlen(json_string));

sway/tree/container.c

@@ -432,8 +432,10 @@ struct sway_container *container_close(struct sway_container *con) {
 
 	if (con->type == C_VIEW) {
 		view_close(con->sway_view);
-	} else {
+	} else if (con->type == C_CONTAINER) {
-		container_for_each_descendant(con, container_close_func, NULL);
+		container_for_each_child(con, container_close_func, NULL);
+	} else if (con->type == C_WORKSPACE) {
+		workspace_for_each_container(con, container_close_func, NULL);
 	}
 
 	return parent;
@@ -465,23 +467,12 @@ struct sway_container *container_view_create(struct sway_container *sibling,
 	return swayc;
 }
 
-void container_descendants(struct sway_container *root,
+struct sway_container *container_find_child(struct sway_container *container,
-		enum sway_container_type type,
-		void (*func)(struct sway_container *item, void *data), void *data) {
-	if (!root->children || !root->children->length) {
-		return;
-	}
-	for (int i = 0; i < root->children->length; ++i) {
-		struct sway_container *item = root->children->items[i];
-		if (item->type == type) {
-			func(item, data);
-		}
-		container_descendants(item, type, func, data);
-	}
-}
-
-struct sway_container *container_find(struct sway_container *container,
 		bool (*test)(struct sway_container *view, void *data), void *data) {
+	if (!sway_assert(container->type == C_CONTAINER ||
+				container->type == C_VIEW, "Expected a container or view")) {
+		return NULL;
+	}
 	if (!container->children) {
 		return NULL;
 	}
@@ -489,16 +480,12 @@ struct sway_container *container_find(struct sway_container *container,
 		struct sway_container *child = container->children->items[i];
 		if (test(child, data)) {
 			return child;
-		} else {
+		}
-			struct sway_container *res = container_find(child, test, data);
+		struct sway_container *res = container_find_child(child, test, data);
 		if (res) {
 			return res;
 		}
 	}
-	}
-	if (container->type == C_WORKSPACE) {
-		return container_find(container->sway_workspace->floating, test, data);
-	}
 	return NULL;
 }
 
@@ -743,26 +730,20 @@ struct sway_container *container_at(struct sway_container *workspace,
 	return NULL;
 }
 
-void container_for_each_descendant(struct sway_container *container,
+void container_for_each_child(struct sway_container *container,
 		void (*f)(struct sway_container *container, void *data),
 		void *data) {
-	if (!container) {
+	if (!sway_assert(container->type == C_CONTAINER ||
+				container->type == C_VIEW, "Expected a container or view")) {
 		return;
 	}
+	f(container, data);
 	if (container->children)  {
 		for (int i = 0; i < container->children->length; ++i) {
 			struct sway_container *child = container->children->items[i];
-			container_for_each_descendant(child, f, data);
+			container_for_each_child(child, f, data);
 		}
 	}
-	if (container->type == C_WORKSPACE)  {
-		struct sway_container *floating = container->sway_workspace->floating;
-		for (int i = 0; i < floating->children->length; ++i) {
-			struct sway_container *child = floating->children->items[i];
-			container_for_each_descendant(child, f, data);
-		}
-	}
-	f(container, data);
 }
 
 bool container_has_ancestor(struct sway_container *descendant,
@@ -1198,13 +1179,12 @@ void container_set_dirty(struct sway_container *container) {
 	list_add(server.dirty_containers, container);
 }
 
-static bool find_urgent_iterator(struct sway_container *con,
+static bool find_urgent_iterator(struct sway_container *con, void *data) {
-		void *data) {
 	return con->type == C_VIEW && view_is_urgent(con->sway_view);
 }
 
 bool container_has_urgent_child(struct sway_container *container) {
-	return container_find(container, find_urgent_iterator, NULL);
+	return container_find_child(container, find_urgent_iterator, NULL);
 }
 
 void container_end_mouse_operation(struct sway_container *container) {
@@ -1236,7 +1216,7 @@ void container_set_fullscreen(struct sway_container *container, bool enable) {
 		container_set_fullscreen(workspace->sway_workspace->fullscreen, false);
 	}
 
-	container_for_each_descendant(container, set_fullscreen_iterator, &enable);
+	container_for_each_child(container, set_fullscreen_iterator, &enable);
 
 	container->is_fullscreen = enable;
 

sway/tree/output.c

@@ -103,6 +103,57 @@ struct sway_container *output_create(
 	return output;
 }
 
+void output_for_each_workspace(struct sway_container *output,
+		void (*f)(struct sway_container *con, void *data), void *data) {
+	if (!sway_assert(output->type == C_OUTPUT, "Expected an output")) {
+		return;
+	}
+	for (int i = 0; i < output->children->length; ++i) {
+		struct sway_container *workspace = output->children->items[i];
+		f(workspace, data);
+	}
+}
+
+void output_for_each_container(struct sway_container *output,
+		void (*f)(struct sway_container *con, void *data), void *data) {
+	if (!sway_assert(output->type == C_OUTPUT, "Expected an output")) {
+		return;
+	}
+	for (int i = 0; i < output->children->length; ++i) {
+		struct sway_container *workspace = output->children->items[i];
+		workspace_for_each_container(workspace, f, data);
+	}
+}
+
+struct sway_container *output_find_workspace(struct sway_container *output,
+		bool (*test)(struct sway_container *con, void *data), void *data) {
+	if (!sway_assert(output->type == C_OUTPUT, "Expected an output")) {
+		return NULL;
+	}
+	for (int i = 0; i < output->children->length; ++i) {
+		struct sway_container *workspace = output->children->items[i];
+		if (test(workspace, data)) {
+			return workspace;
+		}
+	}
+	return NULL;
+}
+
+struct sway_container *output_find_container(struct sway_container *output,
+		bool (*test)(struct sway_container *con, void *data), void *data) {
+	if (!sway_assert(output->type == C_OUTPUT, "Expected an output")) {
+		return NULL;
+	}
+	struct sway_container *result = NULL;
+	for (int i = 0; i < output->children->length; ++i) {
+		struct sway_container *workspace = output->children->items[i];
+		if ((result = workspace_find_container(workspace, test, data))) {
+			return result;
+		}
+	}
+	return NULL;
+}
+
 static int sort_workspace_cmp_qsort(const void *_a, const void *_b) {
 	struct sway_container *a = *(void **)_a;
 	struct sway_container *b = *(void **)_b;
@@ -122,4 +173,3 @@ static int sort_workspace_cmp_qsort(const void *_a, const void *_b) {
 void output_sort_workspaces(struct sway_container *output) {
 	list_stable_sort(output->children, sort_workspace_cmp_qsort);
 }
-

sway/tree/root.c

@@ -256,3 +256,81 @@ void root_record_workspace_pid(pid_t pid) {
 			&pw->output_destroy);
 	wl_list_insert(&pid_workspaces, &pw->link);
 }
+
+void root_for_each_workspace(void (*f)(struct sway_container *con, void *data),
+		void *data) {
+	for (int i = 0; i < root_container.children->length; ++i) {
+		struct sway_container *output = root_container.children->items[i];
+		output_for_each_workspace(output, f, data);
+	}
+}
+
+void root_for_each_container(void (*f)(struct sway_container *con, void *data),
+		void *data) {
+	for (int i = 0; i < root_container.children->length; ++i) {
+		struct sway_container *output = root_container.children->items[i];
+		output_for_each_container(output, f, data);
+	}
+
+	// Scratchpad
+	for (int i = 0; i < root_container.sway_root->scratchpad->length; ++i) {
+		struct sway_container *container =
+			root_container.sway_root->scratchpad->items[i];
+		// If the container has a parent then it's visible on a workspace
+		// and will have been iterated in the previous for loop. So we only
+		// iterate the hidden scratchpad containers here.
+		if (!container->parent) {
+			f(container, data);
+			container_for_each_child(container, f, data);
+		}
+	}
+}
+
+struct sway_container *root_find_output(
+		bool (*test)(struct sway_container *con, void *data), void *data) {
+	for (int i = 0; i < root_container.children->length; ++i) {
+		struct sway_container *output = root_container.children->items[i];
+		if (test(output, data)) {
+			return output;
+		}
+	}
+	return NULL;
+}
+
+struct sway_container *root_find_workspace(
+		bool (*test)(struct sway_container *con, void *data), void *data) {
+	struct sway_container *result = NULL;
+	for (int i = 0; i < root_container.children->length; ++i) {
+		struct sway_container *output = root_container.children->items[i];
+		if ((result = output_find_workspace(output, test, data))) {
+			return result;
+		}
+	}
+	return NULL;
+}
+
+struct sway_container *root_find_container(
+		bool (*test)(struct sway_container *con, void *data), void *data) {
+	struct sway_container *result = NULL;
+	for (int i = 0; i < root_container.children->length; ++i) {
+		struct sway_container *output = root_container.children->items[i];
+		if ((result = output_find_container(output, test, data))) {
+			return result;
+		}
+	}
+
+	// Scratchpad
+	for (int i = 0; i < root_container.sway_root->scratchpad->length; ++i) {
+		struct sway_container *container =
+			root_container.sway_root->scratchpad->items[i];
+		if (!container->parent) {
+			if (test(container, data)) {
+				return container;
+			}
+			if ((result = container_find_child(container, test, data))) {
+				return result;
+			}
+		}
+	}
+	return NULL;
+}

sway/tree/view.c

@@ -899,7 +899,7 @@ static bool find_by_mark_iterator(struct sway_container *con,
 }
 
 struct sway_view *view_find_mark(char *mark) {
-	struct sway_container *container = container_find(&root_container,
+	struct sway_container *container = root_find_container(
 			find_by_mark_iterator, mark);
 	if (!container) {
 		return NULL;
@@ -908,7 +908,7 @@ struct sway_view *view_find_mark(char *mark) {
 }
 
 bool view_find_and_unmark(char *mark) {
-	struct sway_container *container = container_find(&root_container,
+	struct sway_container *container = root_find_container(
 		find_by_mark_iterator, mark);
 	if (!container) {
 		return false;

sway/tree/workspace.c

@@ -244,8 +244,7 @@ struct sway_container *workspace_by_number(const char* name) {
 	if (wbnd.len <= 0) {
 		return NULL;
 	}
-	return container_find(&root_container,
+	return root_find_workspace(_workspace_by_number, (void *) &wbnd);
-			_workspace_by_number, (void *) &wbnd);
 }
 
 static bool _workspace_by_name(struct sway_container *view, void *data) {
@@ -274,11 +273,11 @@ struct sway_container *workspace_by_name(const char *name) {
 	} else if (strcmp(name, "current") == 0) {
 		return current_workspace;
 	} else if (strcasecmp(name, "back_and_forth") == 0) {
-		return prev_workspace_name ? container_find(&root_container,
+		return prev_workspace_name ?
-				_workspace_by_name, (void *)prev_workspace_name) : NULL;
+			root_find_workspace(_workspace_by_name, (void*)prev_workspace_name)
+			: NULL;
 	} else {
-		return container_find(&root_container, _workspace_by_name,
+		return root_find_workspace(_workspace_by_name, (void*)name);
-				(void *)name);
 	}
 }
 
@@ -518,8 +517,7 @@ struct sway_container *workspace_output_get_highest_available(
 			continue;
 		}
 
-		struct sway_container *output = container_find(&root_container,
+		struct sway_container *output = root_find_output(_output_by_name, name);
-				_output_by_name, name);
 		if (output) {
 			return output;
 		}
@@ -528,8 +526,13 @@ struct sway_container *workspace_output_get_highest_available(
 	return NULL;
 }
 
+static bool find_urgent_iterator(struct sway_container *con, void *data) {
+	return con->type == C_VIEW && view_is_urgent(con->sway_view);
+}
+
 void workspace_detect_urgent(struct sway_container *workspace) {
-	bool new_urgent = container_has_urgent_child(workspace);
+	bool new_urgent = (bool)workspace_find_container(workspace,
+			find_urgent_iterator, NULL);
 
 	if (workspace->sway_workspace->urgent != new_urgent) {
 		workspace->sway_workspace->urgent = new_urgent;
@@ -538,6 +541,56 @@ void workspace_detect_urgent(struct sway_container *workspace) {
 	}
 }
 
+void workspace_for_each_container(struct sway_container *ws,
+		void (*f)(struct sway_container *con, void *data), void *data) {
+	if (!sway_assert(ws->type == C_WORKSPACE, "Expected a workspace")) {
+		return;
+	}
+	// Tiling
+	for (int i = 0; i < ws->children->length; ++i) {
+		struct sway_container *container = ws->children->items[i];
+		f(container, data);
+		container_for_each_child(container, f, data);
+	}
+	// Floating
+	for (int i = 0; i < ws->sway_workspace->floating->children->length; ++i) {
+		struct sway_container *container =
+			ws->sway_workspace->floating->children->items[i];
+		f(container, data);
+		container_for_each_child(container, f, data);
+	}
+}
+
+struct sway_container *workspace_find_container(struct sway_container *ws,
+		bool (*test)(struct sway_container *con, void *data), void *data) {
+	if (!sway_assert(ws->type == C_WORKSPACE, "Expected a workspace")) {
+		return NULL;
+	}
+	struct sway_container *result = NULL;
+	// Tiling
+	for (int i = 0; i < ws->children->length; ++i) {
+		struct sway_container *child = ws->children->items[i];
+		if (test(child, data)) {
+			return child;
+		}
+		if ((result = container_find_child(child, test, data))) {
+			return result;
+		}
+	}
+	// Floating
+	for (int i = 0; i < ws->sway_workspace->floating->children->length; ++i) {
+		struct sway_container *child =
+			ws->sway_workspace->floating->children->items[i];
+		if (test(child, data)) {
+			return child;
+		}
+		if ((result = container_find_child(child, test, data))) {
+			return result;
+		}
+	}
+	return NULL;
+}
+
 struct sway_container *workspace_wrap_children(struct sway_container *ws) {
 	struct sway_container *middle = container_create(C_CONTAINER);
 	middle->layout = ws->layout;