Implement type safe arguments and demote sway_container

This commit changes the meaning of sway_container so that it only refers
to layout containers and view containers. Workspaces, outputs and the
root are no longer known as containers. Instead, root, outputs,
workspaces and containers are all a type of node, and containers come in
two types: layout containers and view containers.

In addition to the above, this implements type safe variables. This
means we use specific types such as sway_output and sway_workspace
instead of generic containers or nodes. However, it's worth noting that
in a few places places (eg. seat focus and transactions) referring to
them in a generic way is unavoidable which is why we still use nodes in
some places.

If you want a TL;DR, look at node.h, as well as the struct definitions
for root, output, workspace and container. Note that sway_output now
contains a workspaces list, and workspaces now contain a tiling and
floating list, and containers now contain a pointer back to the
workspace.

There are now functions for seat_get_focused_workspace and
seat_get_focused_container. The latter will return NULL if a workspace
itself is focused. Most other seat functions like seat_get_focus and
seat_set_focus now accept and return nodes.

In the config->handler_context struct, current_container has been
replaced with three pointers: node, container and workspace. node is the
same as what current_container was, while workspace is the workspace
that the node resides on and container is the actual container, which
may be NULL if a workspace itself is focused.

The global root_container variable has been replaced with one simply
called root, which is a pointer to the sway_root instance.

The way outputs are created, enabled, disabled and destroyed has
changed. Previously we'd wrap the sway_output in a container when it is
enabled, but as we don't have containers any more it needs a different
approach. The output_create and output_destroy functions previously
created/destroyed the container, but now they create/destroy the
sway_output. There is a new function output_disable to disable an output
without destroying it.

Containers have a new view property. If this is populated then the
container is a view container, otherwise it's a layout container. Like
before, this property is immutable for the life of the container.

Containers have both a `sway_container *parent` and
`sway_workspace *workspace`. As we use specific types now, parent cannot
point to a workspace so it'll be NULL for containers which are direct
children of the workspace. The workspace property is set for all
containers, except those which are hidden in the scratchpad as they have
no workspace.

In some cases we need to refer to workspaces in a container-like way.
For example, workspaces have layout and children, but when using
specific types this makes it difficult. Likewise, it's difficult for a
container to get its parent's layout when the parent could be another
container or a workspace. To make it easier, some helper functions have
been created: container_parent_layout and container_get_siblings.

container_remove_child has been renamed to container_detach and
container_replace_child has been renamed to container_replace.

`container_handle_fullscreen_reparent(con, old_parent)` has had the
old_parent removed. We now unfullscreen the workspace when detaching the
container, so this function is simplified and only needs one argument
now.

container_notify_subtree_changed has been renamed to
container_update_representation. This is more descriptive of its
purpose. I also wanted to be able to call it with whatever container was
changed rather than the container's parent, which makes bubbling up to
the workspace easier.

There are now state structs per node thing. ie. sway_output_state,
sway_workspace_state and sway_container_state.

The focus, move and layout commands have been completely refactored to
work with the specific types. I considered making these a separate PR,
but I'd be backporting my changes only to replace them again, and it's
easier just to test everything at once.

1 files changed, 254 insertions, 260 deletions

diff --git a/sway/input/seat.c b/sway/input/seat.c
index 4b7c7893..2f7a3318 100644
--- a/sway/input/seat.c
+++ b/sway/input/seat.c
@@ -47,48 +47,36 @@ void seat_destroy(struct sway_seat *seat) {
                 seat_device_destroy(seat_device);
         }
         sway_cursor_destroy(seat->cursor);
-        wl_list_remove(&seat->new_container.link);
+        wl_list_remove(&seat->new_node.link);
         wl_list_remove(&seat->new_drag_icon.link);
         wl_list_remove(&seat->link);
         wlr_seat_destroy(seat->wlr_seat);
 }
 
-static struct sway_seat_container *seat_container_from_container(
-                struct sway_seat *seat, struct sway_container *con);
+static struct sway_seat_node *seat_node_from_node(
+                struct sway_seat *seat, struct sway_node *node);
 
-static void seat_container_destroy(struct sway_seat_container *seat_con) {
-        struct sway_container *con = seat_con->container;
-        struct sway_container *child = NULL;
-
-        if (con->children != NULL) {
-                for (int i = 0; i < con->children->length; ++i) {
-                        child = con->children->items[i];
-                        struct sway_seat_container *seat_child =
-                                seat_container_from_container(seat_con->seat, child);
-                        seat_container_destroy(seat_child);
-                }
-        }
-
-        wl_list_remove(&seat_con->destroy.link);
-        wl_list_remove(&seat_con->link);
-        free(seat_con);
+static void seat_node_destroy(struct sway_seat_node *seat_node) {
+        wl_list_remove(&seat_node->destroy.link);
+        wl_list_remove(&seat_node->link);
+        free(seat_node);
 }
 
 /**
  * Activate all views within this container recursively.
  */
-static void seat_send_activate(struct sway_container *con,
-                struct sway_seat *seat) {
-        if (con->type == C_VIEW) {
-                if (!seat_is_input_allowed(seat, con->sway_view->surface)) {
+static void seat_send_activate(struct sway_node *node, struct sway_seat *seat) {
+        if (node_is_view(node)) {
+                if (!seat_is_input_allowed(seat, node->sway_container->view->surface)) {
                         wlr_log(WLR_DEBUG, "Refusing to set focus, input is inhibited");
                         return;
                 }
-                view_set_activated(con->sway_view, true);
+                view_set_activated(node->sway_container->view, true);
         } else {
-                for (int i = 0; i < con->children->length; ++i) {
-                        struct sway_container *child = con->children->items[i];
-                        seat_send_activate(child, seat);
+                list_t *children = node_get_children(node);
+                for (int i = 0; i < children->length; ++i) {
+                        struct sway_container *child = children->items[i];
+                        seat_send_activate(&child->node, seat);
                 }
         }
 }
@@ -98,14 +86,15 @@ static void seat_send_activate(struct sway_container *con,
  * If con is a container, set all child views as active and don't enable
  * keyboard input on any.
  */
-static void seat_send_focus(struct sway_container *con,
-                struct sway_seat *seat) {
-        seat_send_activate(con, seat);
+static void seat_send_focus(struct sway_node *node, struct sway_seat *seat) {
+        seat_send_activate(node, seat);
 
-        if (con->type == C_VIEW
-                        && seat_is_input_allowed(seat, con->sway_view->surface)) {
+        struct sway_view *view = node->type == N_CONTAINER ?
+                node->sway_container->view : NULL;
+
+        if (view && seat_is_input_allowed(seat, view->surface)) {
 #ifdef HAVE_XWAYLAND
-                if (con->sway_view->type == SWAY_VIEW_XWAYLAND) {
+                if (view->type == SWAY_VIEW_XWAYLAND) {
                         struct wlr_xwayland *xwayland =
                                 seat->input->server->xwayland.wlr_xwayland;
                         wlr_xwayland_set_seat(xwayland, seat->wlr_seat);
@@ -114,71 +103,67 @@ static void seat_send_focus(struct sway_container *con,
                 struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat->wlr_seat);
                 if (keyboard) {
                         wlr_seat_keyboard_notify_enter(seat->wlr_seat,
-                                        con->sway_view->surface, keyboard->keycodes,
+                                        view->surface, keyboard->keycodes,
                                         keyboard->num_keycodes, &keyboard->modifiers);
                 } else {
                         wlr_seat_keyboard_notify_enter(
-                                        seat->wlr_seat, con->sway_view->surface, NULL, 0, NULL);
+                                        seat->wlr_seat, view->surface, NULL, 0, NULL);
                 }
         }
 }
 
-void seat_focus_inactive_children_for_each(struct sway_seat *seat,
-                struct sway_container *container,
-                void (*f)(struct sway_container *container, void *data), void *data) {
-        struct sway_seat_container *current = NULL;
+void seat_for_each_node(struct sway_seat *seat,
+                void (*f)(struct sway_node *node, void *data), void *data) {
+        struct sway_seat_node *current = NULL;
         wl_list_for_each(current, &seat->focus_stack, link) {
-                if (current->container->parent == NULL) {
-                        continue;
-                }
-                if (current->container->parent == container) {
-                        f(current->container, data);
-                }
+                f(current->node, data);
         }
 }
 
 struct sway_container *seat_get_focus_inactive_view(struct sway_seat *seat,
-                struct sway_container *ancestor) {
-        if (ancestor->type == C_VIEW) {
-                return ancestor;
+                struct sway_node *ancestor) {
+        if (ancestor->type == N_CONTAINER && ancestor->sway_container->view) {
+                return ancestor->sway_container;
         }
-        struct sway_seat_container *current;
+        struct sway_seat_node *current;
         wl_list_for_each(current, &seat->focus_stack, link) {
-                struct sway_container *con = current->container;
-                if (con->type == C_VIEW && container_has_ancestor(con, ancestor)) {
-                        return con;
+                struct sway_node *node = current->node;
+                if (node->type == N_CONTAINER && node->sway_container->view &&
+                                node_has_ancestor(node, ancestor)) {
+                        return node->sway_container;
                 }
         }
         return NULL;
 }
 
-static void handle_seat_container_destroy(struct wl_listener *listener,
-                void *data) {
-        struct sway_seat_container *seat_con =
-                wl_container_of(listener, seat_con, destroy);
-        struct sway_seat *seat = seat_con->seat;
-        struct sway_container *con = seat_con->container;
-        struct sway_container *parent = con->parent;
-        struct sway_container *focus = seat_get_focus(seat);
+static void handle_seat_node_destroy(struct wl_listener *listener, void *data) {
+        struct sway_seat_node *seat_node =
+                wl_container_of(listener, seat_node, destroy);
+        struct sway_seat *seat = seat_node->seat;
+        struct sway_node *node = seat_node->node;
+        struct sway_node *parent = node_get_parent(node);
+        struct sway_node *focus = seat_get_focus(seat);
 
         bool set_focus =
                 focus != NULL &&
-                (focus == con || container_has_ancestor(focus, con)) &&
-                con->type != C_WORKSPACE;
+                (focus == node || node_has_ancestor(focus, node)) &&
+                node->type == N_CONTAINER;
 
-        seat_container_destroy(seat_con);
+        seat_node_destroy(seat_node);
 
         if (set_focus) {
-                struct sway_container *next_focus = NULL;
+                struct sway_node *next_focus = NULL;
                 while (next_focus == NULL) {
-                        next_focus = seat_get_focus_inactive_view(seat, parent);
+                        struct sway_container *con =
+                                seat_get_focus_inactive_view(seat, parent);
+                        next_focus = con ? &con->node : NULL;
 
-                        if (next_focus == NULL && parent->type == C_WORKSPACE) {
+                        if (next_focus == NULL && parent->type == N_WORKSPACE) {
                                 next_focus = parent;
                                 break;
                         }
 
-                        parent = parent->parent;
+                        parent = node_get_parent(parent);
                 }
 
                 // the structure change might have caused it to move up to the top of
@@ -191,39 +176,39 @@ static void handle_seat_container_destroy(struct wl_listener *listener,
         }
 }
 
-static struct sway_seat_container *seat_container_from_container(
-                struct sway_seat *seat, struct sway_container *con) {
-        if (con->type == C_ROOT || con->type == C_OUTPUT) {
-                // these don't get seat containers ever
+static struct sway_seat_node *seat_node_from_node(
+                struct sway_seat *seat, struct sway_node *node) {
+        if (node->type == N_ROOT || node->type == N_OUTPUT) {
+                // these don't get seat nodes ever
                 return NULL;
         }
 
-        struct sway_seat_container *seat_con = NULL;
-        wl_list_for_each(seat_con, &seat->focus_stack, link) {
-                if (seat_con->container == con) {
-                        return seat_con;
+        struct sway_seat_node *seat_node = NULL;
+        wl_list_for_each(seat_node, &seat->focus_stack, link) {
+                if (seat_node->node == node) {
+                        return seat_node;
                 }
         }
 
-        seat_con = calloc(1, sizeof(struct sway_seat_container));
-        if (seat_con == NULL) {
-                wlr_log(WLR_ERROR, "could not allocate seat container");
+        seat_node = calloc(1, sizeof(struct sway_seat_node));
+        if (seat_node == NULL) {
+                wlr_log(WLR_ERROR, "could not allocate seat node");
                 return NULL;
         }
 
-        seat_con->container = con;
-        seat_con->seat = seat;
-        wl_list_insert(seat->focus_stack.prev, &seat_con->link);
-        wl_signal_add(&con->events.destroy, &seat_con->destroy);
-        seat_con->destroy.notify = handle_seat_container_destroy;
+        seat_node->node = node;
+        seat_node->seat = seat;
+        wl_list_insert(seat->focus_stack.prev, &seat_node->link);
+        wl_signal_add(&node->events.destroy, &seat_node->destroy);
+        seat_node->destroy.notify = handle_seat_node_destroy;
 
-        return seat_con;
+        return seat_node;
 }
 
-static void handle_new_container(struct wl_listener *listener, void *data) {
-        struct sway_seat *seat = wl_container_of(listener, seat, new_container);
-        struct sway_container *con = data;
-        seat_container_from_container(seat, con);
+static void handle_new_node(struct wl_listener *listener, void *data) {
+        struct sway_seat *seat = wl_container_of(listener, seat, new_node);
+        struct sway_node *node = data;
+        seat_node_from_node(seat, node);
 }
 
 static void drag_icon_damage_whole(struct sway_drag_icon *icon) {
@@ -272,8 +257,7 @@ static void drag_icon_handle_unmap(struct wl_listener *listener, void *data) {
         drag_icon_damage_whole(icon);
 }
 
-static void drag_icon_handle_destroy(struct wl_listener *listener,
-                void *data) {
+static void drag_icon_handle_destroy(struct wl_listener *listener, void *data) {
         struct sway_drag_icon *icon = wl_container_of(listener, icon, destroy);
         icon->wlr_drag_icon->data = NULL;
         wl_list_remove(&icon->link);
@@ -305,20 +289,29 @@ static void handle_new_drag_icon(struct wl_listener *listener, void *data) {
         icon->destroy.notify = drag_icon_handle_destroy;
         wl_signal_add(&wlr_drag_icon->events.destroy, &icon->destroy);
 
-        wl_list_insert(&root_container.sway_root->drag_icons, &icon->link);
+        wl_list_insert(&root->drag_icons, &icon->link);
 
         drag_icon_update_position(icon);
 }
 
-static void collect_focus_iter(struct sway_container *con, void *data) {
+static void collect_focus_iter(struct sway_node *node, void *data) {
         struct sway_seat *seat = data;
-        struct sway_seat_container *seat_con =
-                seat_container_from_container(seat, con);
-        if (!seat_con) {
+        struct sway_seat_node *seat_node = seat_node_from_node(seat, node);
+        if (!seat_node) {
                 return;
         }
-        wl_list_remove(&seat_con->link);
-        wl_list_insert(&seat->focus_stack, &seat_con->link);
+        wl_list_remove(&seat_node->link);
+        wl_list_insert(&seat->focus_stack, &seat_node->link);
+}
+
+static void collect_focus_workspace_iter(struct sway_workspace *workspace,
+                void *data) {
+        collect_focus_iter(&workspace->node, data);
+}
+
+static void collect_focus_container_iter(struct sway_container *container,
+                void *data) {
+        collect_focus_iter(&container->node, data);
 }
 
 struct sway_seat *seat_create(struct sway_input_manager *input,
@@ -345,12 +338,11 @@ struct sway_seat *seat_create(struct sway_input_manager *input,
         // init the focus stack
         wl_list_init(&seat->focus_stack);
 
-        root_for_each_workspace(collect_focus_iter, seat);
-        root_for_each_container(collect_focus_iter, seat);
+        root_for_each_workspace(collect_focus_workspace_iter, seat);
+        root_for_each_container(collect_focus_container_iter, seat);
 
-        wl_signal_add(&root_container.sway_root->events.new_container,
-                &seat->new_container);
-        seat->new_container.notify = handle_new_container;
+        wl_signal_add(&root->events.new_node, &seat->new_node);
+        seat->new_node.notify = handle_new_node;
 
         wl_signal_add(&seat->wlr_seat->events.new_drag_icon, &seat->new_drag_icon);
         seat->new_drag_icon.notify = handle_new_drag_icon;
@@ -388,19 +380,11 @@ static void seat_apply_input_config(struct sway_seat *seat,
         if (mapped_to_output != NULL) {
                 wlr_log(WLR_DEBUG, "Mapping input device %s to output %s",
                         sway_device->input_device->identifier, mapped_to_output);
-                struct sway_container *output = NULL;
-                for (int i = 0; i < root_container.children->length; ++i) {
-                        struct sway_container *_output = root_container.children->items[i];
-                        if (strcasecmp(_output->name, mapped_to_output) == 0) {
-                                output = _output;
-                                break;
-                        }
-                }
+                struct sway_output *output = output_by_name(mapped_to_output);
                 if (output) {
                         wlr_cursor_map_input_to_output(seat->cursor->cursor,
-                                sway_device->input_device->wlr_device,
-                                output->sway_output->wlr_output);
-                        wlr_log(WLR_DEBUG, "Mapped to output %s", output->name);
+                                sway_device->input_device->wlr_device, output->wlr_output);
+                        wlr_log(WLR_DEBUG, "Mapped to output %s", output->wlr_output->name);
                 }
         }
 }
@@ -423,12 +407,12 @@ static void seat_configure_keyboard(struct sway_seat *seat,
         sway_keyboard_configure(seat_device->keyboard);
         wlr_seat_set_keyboard(seat->wlr_seat,
                         seat_device->input_device->wlr_device);
-        struct sway_container *focus = seat_get_focus(seat);
-        if (focus && focus->type == C_VIEW) {
+        struct sway_node *focus = seat_get_focus(seat);
+        if (focus && node_is_view(focus)) {
                 // force notify reenter to pick up the new configuration
                 wlr_seat_keyboard_clear_focus(seat->wlr_seat);
                 wlr_seat_keyboard_notify_enter(seat->wlr_seat,
-                                focus->sway_view->surface, wlr_keyboard->keycodes,
+                                focus->sway_container->view->surface, wlr_keyboard->keycodes,
                                 wlr_keyboard->num_keycodes, &wlr_keyboard->modifiers);
         }
 }
@@ -461,8 +445,7 @@ static struct sway_seat_device *seat_get_device(struct sway_seat *seat,
 
 void seat_configure_device(struct sway_seat *seat,
                 struct sway_input_device *input_device) {
-        struct sway_seat_device *seat_device =
-                seat_get_device(seat, input_device);
+        struct sway_seat_device *seat_device = seat_get_device(seat, input_device);
         if (!seat_device) {
                 return;
         }
@@ -512,8 +495,7 @@ void seat_add_device(struct sway_seat *seat,
 
 void seat_remove_device(struct sway_seat *seat,
                 struct sway_input_device *input_device) {
-        struct sway_seat_device *seat_device =
-                seat_get_device(seat, input_device);
+        struct sway_seat_device *seat_device = seat_get_device(seat, input_device);
 
         if (!seat_device) {
                 return;
@@ -539,11 +521,9 @@ void seat_configure_xcursor(struct sway_seat *seat) {
                 }
         }
 
-        for (int i = 0; i < root_container.children->length; ++i) {
-                struct sway_container *output_container =
-                        root_container.children->items[i];
-                struct wlr_output *output =
-                        output_container->sway_output->wlr_output;
+        for (int i = 0; i < root->outputs->length; ++i) {
+                struct sway_output *sway_output = root->outputs->items[i];
+                struct wlr_output *output = sway_output->wlr_output;
                 bool result =
                         wlr_xcursor_manager_load(seat->cursor->xcursor_manager,
                                 output->scale);
@@ -566,17 +546,20 @@ bool seat_is_input_allowed(struct sway_seat *seat,
         return !seat->exclusive_client || seat->exclusive_client == client;
 }
 
+static void send_unfocus(struct sway_container *con, void *data) {
+        if (con->view) {
+                view_set_activated(con->view, false);
+        }
+}
+
 // Unfocus the container and any children (eg. when leaving `focus parent`)
-static void seat_send_unfocus(struct sway_container *container,
-                struct sway_seat *seat) {
-        if (container->type == C_VIEW) {
-                wlr_seat_keyboard_clear_focus(seat->wlr_seat);
-                view_set_activated(container->sway_view, false);
+static void seat_send_unfocus(struct sway_node *node, struct sway_seat *seat) {
+        wlr_seat_keyboard_clear_focus(seat->wlr_seat);
+        if (node->type == N_WORKSPACE) {
+                workspace_for_each_container(node->sway_workspace, send_unfocus, seat);
         } else {
-                for (int i = 0; i < container->children->length; ++i) {
-                        struct sway_container *child = container->children->items[i];
-                        seat_send_unfocus(child, seat);
-                }
+                send_unfocus(node->sway_container, seat);
+                container_for_each_child(node->sway_container, send_unfocus, seat);
         }
 }
 
@@ -586,26 +569,23 @@ static int handle_urgent_timeout(void *data) {
         return 0;
 }
 
-void seat_set_focus_warp(struct sway_seat *seat,
-                struct sway_container *container, bool warp, bool notify) {
+void seat_set_focus_warp(struct sway_seat *seat, struct sway_node *node,
+                bool warp, bool notify) {
         if (seat->focused_layer) {
                 return;
         }
 
-        struct sway_container *last_focus = seat_get_focus(seat);
-        if (last_focus == container) {
+        struct sway_node *last_focus = seat_get_focus(seat);
+        if (last_focus == node) {
                 return;
         }
 
-        struct sway_container *last_workspace = last_focus;
-        if (last_workspace && last_workspace->type != C_WORKSPACE) {
-                last_workspace = container_parent(last_workspace, C_WORKSPACE);
-        }
+        struct sway_workspace *last_workspace = seat_get_focused_workspace(seat);
 
-        if (container == NULL) {
+        if (node == NULL) {
                 // Close any popups on the old focus
-                if (last_focus->type == C_VIEW) {
-                        view_close_popups(last_focus->sway_view);
+                if (node_is_view(last_focus)) {
+                        view_close_popups(last_focus->sway_container->view);
                 }
                 seat_send_unfocus(last_focus, seat);
                 seat->has_focus = false;
@@ -613,69 +593,70 @@ void seat_set_focus_warp(struct sway_seat *seat,
                 return;
         }
 
-        struct sway_container *new_workspace = container;
-        if (new_workspace->type != C_WORKSPACE) {
-                new_workspace = container_parent(new_workspace, C_WORKSPACE);
-        }
+        struct sway_workspace *new_workspace = node->type == N_WORKSPACE ?
+                node->sway_workspace : node->sway_container->workspace;
+        struct sway_container *container = node->type == N_CONTAINER ?
+                node->sway_container : NULL;
 
-        if (last_workspace == new_workspace
-                        && last_workspace->sway_workspace->fullscreen
-                        && !container_is_fullscreen_or_child(container)) {
+        // Deny setting focus to a view which is hidden by a fullscreen container
+        if (new_workspace && new_workspace->fullscreen && container &&
+                        !container_is_fullscreen_or_child(container)) {
                 return;
         }
 
-        struct sway_container *last_output = last_focus;
-        if (last_output && last_output->type != C_OUTPUT) {
-                last_output = container_parent(last_output, C_OUTPUT);
-        }
-        struct sway_container *new_output = container;
-        if (new_output->type != C_OUTPUT) {
-                new_output = container_parent(new_output, C_OUTPUT);
-        }
+        struct sway_output *last_output = last_workspace ?
+                last_workspace->output : NULL;
+        struct sway_output *new_output = new_workspace->output;
 
         // find new output's old workspace, which might have to be removed if empty
-        struct sway_container *new_output_last_ws = NULL;
+        struct sway_workspace *new_output_last_ws = NULL;
         if (new_output && last_output != new_output) {
-                new_output_last_ws = seat_get_active_child(seat, new_output);
+                new_output_last_ws = output_get_active_workspace(new_output);
         }
 
-        if (container->parent) {
-                struct sway_seat_container *seat_con =
-                        seat_container_from_container(seat, container);
-                if (seat_con == NULL) {
-                        return;
-                }
-
-                // put all the ancestors of this container on top of the focus stack
-                struct sway_seat_container *parent =
-                        seat_container_from_container(seat, container->parent);
+        // Put the container parents on the focus stack, then the workspace, then
+        // the focused container.
+        if (container) {
+                struct sway_container *parent = container->parent;
                 while (parent) {
-                        wl_list_remove(&parent->link);
-                        wl_list_insert(&seat->focus_stack, &parent->link);
-                        container_set_dirty(parent->container);
-
-                        parent = seat_container_from_container(seat,
-                                        parent->container->parent);
+                        struct sway_seat_node *seat_node =
+                                seat_node_from_node(seat, &parent->node);
+                        wl_list_remove(&seat_node->link);
+                        wl_list_insert(&seat->focus_stack, &seat_node->link);
+                        node_set_dirty(&parent->node);
+                        parent = parent->parent;
                 }
-
-                wl_list_remove(&seat_con->link);
-                wl_list_insert(&seat->focus_stack, &seat_con->link);
+        }
+        if (new_workspace) {
+                struct sway_seat_node *seat_node =
+                        seat_node_from_node(seat, &new_workspace->node);
+                wl_list_remove(&seat_node->link);
+                wl_list_insert(&seat->focus_stack, &seat_node->link);
+                node_set_dirty(&new_workspace->node);
+        }
+        if (container) {
+                struct sway_seat_node *seat_node =
+                        seat_node_from_node(seat, &container->node);
+                wl_list_remove(&seat_node->link);
+                wl_list_insert(&seat->focus_stack, &seat_node->link);
+                node_set_dirty(&container->node);
 
                 if (last_focus) {
                         seat_send_unfocus(last_focus, seat);
-                        container_set_dirty(last_focus);
+                        node_set_dirty(last_focus);
+                        struct sway_node *last_parent = node_get_parent(last_focus);
+                        if (last_parent) {
+                                node_set_dirty(last_parent);
+                        }
                 }
-                seat_send_focus(container, seat);
-
-                container_set_dirty(container);
-                container_set_dirty(container->parent); // for focused_inactive_child
+                seat_send_focus(&container->node, seat);
         }
 
         // emit ipc events
         if (notify && new_workspace && last_workspace != new_workspace) {
                  ipc_event_workspace(last_workspace, new_workspace, "focus");
         }
-        if (container->type == C_VIEW) {
+        if (container && container->view) {
                 ipc_event_window(container, "focus");
         }
 
@@ -684,14 +665,14 @@ void seat_set_focus_warp(struct sway_seat *seat,
         }
 
         // Close any popups on the old focus
-        if (last_focus && last_focus->type == C_VIEW) {
-                view_close_popups(last_focus->sway_view);
+        if (last_focus && node_is_view(last_focus)) {
+                view_close_popups(last_focus->sway_container->view);
         }
 
         // If urgent, either unset the urgency or start a timer to unset it
-        if (container->type == C_VIEW && view_is_urgent(container->sway_view) &&
-                        !container->sway_view->urgent_timer) {
-                struct sway_view *view = container->sway_view;
+        if (container && container->view && view_is_urgent(container->view) &&
+                        !container->view->urgent_timer) {
+                struct sway_view *view = container->view;
                 if (last_workspace && last_workspace != new_workspace &&
                                 config->urgent_timeout > 0) {
                         view->urgent_timer = wl_event_loop_add_timer(server.wl_event_loop,
@@ -711,12 +692,15 @@ void seat_set_focus_warp(struct sway_seat *seat,
 
         // If we've focused a floating container, bring it to the front.
         // We do this by putting it at the end of the floating list.
-        struct sway_container *floater = container;
-        while (floater->parent && floater->parent->type != C_WORKSPACE) {
-                floater = floater->parent;
-        }
-        if (container_is_floating(floater)) {
-                list_move_to_end(floater->parent->sway_workspace->floating, floater);
+        if (container) {
+                struct sway_container *floater = container;
+                while (floater->parent) {
+                        floater = floater->parent;
+                }
+                if (container_is_floating(floater)) {
+                        list_move_to_end(floater->workspace->floating, floater);
+                        node_set_dirty(&floater->workspace->node);
+                }
         }
 
         if (last_focus) {
@@ -727,11 +711,8 @@ void seat_set_focus_warp(struct sway_seat *seat,
                 if (config->mouse_warping && warp && new_output != last_output) {
                                 double x = container->x + container->width / 2.0;
                                 double y = container->y + container->height / 2.0;
-                                struct wlr_output *wlr_output =
-                                        new_output->sway_output->wlr_output;
-                                if (!wlr_output_layout_contains_point(
-                                                root_container.sway_root->output_layout,
-                                                wlr_output, seat->cursor->cursor->x,
+                                if (!wlr_output_layout_contains_point(root->output_layout,
+                                                new_output->wlr_output, seat->cursor->cursor->x,
                                                 seat->cursor->cursor->y)) {
                                         wlr_cursor_warp(seat->cursor->cursor, NULL, x, y);
                                         cursor_send_pointer_motion(seat->cursor, 0, true);
@@ -744,9 +725,8 @@ void seat_set_focus_warp(struct sway_seat *seat,
         update_debug_tree();
 }
 
-void seat_set_focus(struct sway_seat *seat,
-                struct sway_container *container) {
-        seat_set_focus_warp(seat, container, true, true);
+void seat_set_focus(struct sway_seat *seat, struct sway_node *node) {
+        seat_set_focus_warp(seat, node, true, true);
 }
 
 void seat_set_focus_surface(struct sway_seat *seat,
@@ -755,12 +735,11 @@ void seat_set_focus_surface(struct sway_seat *seat,
                 return;
         }
         if (seat->has_focus && unfocus) {
-                struct sway_container *focus = seat_get_focus(seat);
+                struct sway_node *focus = seat_get_focus(seat);
                 seat_send_unfocus(focus, seat);
                 seat->has_focus = false;
         }
-        struct wlr_keyboard *keyboard =
-                wlr_seat_get_keyboard(seat->wlr_seat);
+        struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat->wlr_seat);
         if (keyboard) {
                 wlr_seat_keyboard_notify_enter(seat->wlr_seat, surface,
                         keyboard->keycodes, keyboard->num_keycodes, &keyboard->modifiers);
@@ -773,11 +752,8 @@ void seat_set_focus_layer(struct sway_seat *seat,
                 struct wlr_layer_surface *layer) {
         if (!layer && seat->focused_layer) {
                 seat->focused_layer = NULL;
-                struct sway_container *previous =
-                        seat_get_focus_inactive(seat, &root_container);
+                struct sway_node *previous = seat_get_focus_inactive(seat, &root->node);
                 if (previous) {
-                        wlr_log(WLR_DEBUG, "Returning focus to %p %s '%s'", previous,
-                                        container_type_to_str(previous->type), previous->name);
                         // Hack to get seat to re-focus the return value of get_focus
                         seat_set_focus(seat, NULL);
                         seat_set_focus(seat, previous);
@@ -798,13 +774,9 @@ void seat_set_exclusive_client(struct sway_seat *seat,
                 seat->exclusive_client = client;
                 // Triggers a refocus of the topmost surface layer if necessary
                 // TODO: Make layer surface focus per-output based on cursor position
-                for (int i = 0; i < root_container.children->length; ++i) {
-                        struct sway_container *output = root_container.children->items[i];
-                        if (!sway_assert(output->type == C_OUTPUT,
-                                                "root container has non-output child")) {
-                                continue;
-                        }
-                        arrange_layers(output->sway_output);
+                for (int i = 0; i < root->outputs->length; ++i) {
+                        struct sway_output *output = root->outputs->items[i];
+                        arrange_layers(output);
                 }
                 return;
         }
@@ -814,9 +786,9 @@ void seat_set_exclusive_client(struct sway_seat *seat,
                 }
         }
         if (seat->has_focus) {
-                struct sway_container *focus = seat_get_focus(seat);
-                if (focus->type == C_VIEW && wl_resource_get_client(
-                                        focus->sway_view->surface->resource) != client) {
+                struct sway_node *focus = seat_get_focus(seat);
+                if (node_is_view(focus) && wl_resource_get_client(
+                                        focus->sway_container->view->surface->resource) != client) {
                         seat_set_focus(seat, NULL);
                 }
         }
@@ -837,79 +809,101 @@ void seat_set_exclusive_client(struct sway_seat *seat,
         seat->exclusive_client = client;
 }
 
-struct sway_container *seat_get_focus_inactive(struct sway_seat *seat,
-                struct sway_container *con) {
-        if (con->type == C_WORKSPACE && !con->children->length &&
-                        !con->sway_workspace->floating->length) {
-                return con;
-        }
-        if (con->type == C_VIEW) {
-                return con;
+struct sway_node *seat_get_focus_inactive(struct sway_seat *seat,
+                struct sway_node *node) {
+        if (node_is_view(node)) {
+                return node;
         }
-        struct sway_seat_container *current;
+        struct sway_seat_node *current;
         wl_list_for_each(current, &seat->focus_stack, link) {
-                if (container_has_ancestor(current->container, con)) {
-                        return current->container;
+                if (node_has_ancestor(current->node, node)) {
+                        return current->node;
                 }
         }
+        if (node->type == N_WORKSPACE) {
+                return node;
+        }
         return NULL;
 }
 
 struct sway_container *seat_get_focus_inactive_tiling(struct sway_seat *seat,
-                struct sway_container *ancestor) {
-        if (ancestor->type == C_WORKSPACE && !ancestor->children->length) {
-                return ancestor;
+                struct sway_workspace *workspace) {
+        if (!workspace->tiling->length) {
+                return NULL;
         }
-        struct sway_seat_container *current;
+        struct sway_seat_node *current;
         wl_list_for_each(current, &seat->focus_stack, link) {
-                struct sway_container *con = current->container;
-                if (!container_is_floating_or_child(con) &&
-                                container_has_ancestor(current->container, ancestor)) {
-                        return con;
+                struct sway_node *node = current->node;
+                if (node->type == N_CONTAINER &&
+                                !container_is_floating_or_child(node->sway_container) &&
+                                node->sway_container->workspace == workspace) {
+                        return node->sway_container;
                 }
         }
         return NULL;
 }
 
 struct sway_container *seat_get_focus_inactive_floating(struct sway_seat *seat,
-                struct sway_container *ancestor) {
-        if (ancestor->type == C_WORKSPACE &&
-                        !ancestor->sway_workspace->floating->length) {
+                struct sway_workspace *workspace) {
+        if (!workspace->floating->length) {
                 return NULL;
         }
-        struct sway_seat_container *current;
+        struct sway_seat_node *current;
         wl_list_for_each(current, &seat->focus_stack, link) {
-                struct sway_container *con = current->container;
-                if (container_is_floating_or_child(con) &&
-                                container_has_ancestor(current->container, ancestor)) {
-                        return con;
+                struct sway_node *node = current->node;
+                if (node->type == N_CONTAINER &&
+                                container_is_floating_or_child(node->sway_container) &&
+                                node->sway_container->workspace == workspace) {
+                        return node->sway_container;
                 }
         }
         return NULL;
 }
 
-struct sway_container *seat_get_active_child(struct sway_seat *seat,
-                struct sway_container *parent) {
-        if (parent->type == C_VIEW) {
+struct sway_node *seat_get_active_child(struct sway_seat *seat,
+                struct sway_node *parent) {
+        if (node_is_view(parent)) {
                 return parent;
         }
-        struct sway_seat_container *current;
+        struct sway_seat_node *current;
         wl_list_for_each(current, &seat->focus_stack, link) {
-                struct sway_container *con = current->container;
-                if (con->parent == parent) {
-                        return con;
+                struct sway_node *node = current->node;
+                if (node_get_parent(node) == parent) {
+                        return node;
                 }
         }
         return NULL;
 }
 
-struct sway_container *seat_get_focus(struct sway_seat *seat) {
+struct sway_node *seat_get_focus(struct sway_seat *seat) {
         if (!seat->has_focus) {
                 return NULL;
         }
-        struct sway_seat_container *current =
+        struct sway_seat_node *current =
                 wl_container_of(seat->focus_stack.next, current, link);
-        return current->container;
+        return current->node;
+}
+
+struct sway_workspace *seat_get_focused_workspace(struct sway_seat *seat) {
+        struct sway_node *focus = seat_get_focus(seat);
+        if (!focus) {
+                return NULL;
+        }
+        if (focus->type == N_CONTAINER) {
+                return focus->sway_container->workspace;
+        }
+        if (focus->type == N_WORKSPACE) {
+                return focus->sway_workspace;
+        }
+        return NULL; // unreachable
+}
+
+struct sway_container *seat_get_focused_container(struct sway_seat *seat) {
+        struct sway_node *focus = seat_get_focus(seat);
+        if (focus && focus->type == N_CONTAINER) {
+                return focus->sway_container;
+        }
+        return NULL;
 }
 
 void seat_apply_config(struct sway_seat *seat,