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.

14 files changed, 286 insertions, 201 deletions

diff --git a/include/sway/config.h b/include/sway/config.h
index 6024f0f6..2fef0081 100644
--- a/include/sway/config.h
+++ b/include/sway/config.h
@@ -407,7 +407,9 @@ struct sway_config {
                 struct output_config *output_config;
                 struct seat_config *seat_config;
                 struct sway_seat *seat;
-                struct sway_container *current_container;
+                struct sway_node *node;
+                struct sway_container *container;
+                struct sway_workspace *workspace;
                 bool using_criteria;
                 struct {
                         int argc;
@@ -486,8 +488,7 @@ struct output_config *new_output_config(const char *name);
 
 void merge_output_config(struct output_config *dst, struct output_config *src);
 
-void apply_output_config(struct output_config *oc,
-                struct sway_container *output);
+void apply_output_config(struct output_config *oc, struct sway_output *output);
 
 struct output_config *store_output_config(struct output_config *oc);
 
diff --git a/include/sway/desktop/transaction.h b/include/sway/desktop/transaction.h
index 7ac924e7..66e8c9a2 100644
--- a/include/sway/desktop/transaction.h
+++ b/include/sway/desktop/transaction.h
@@ -1,7 +1,6 @@
 #ifndef _SWAY_TRANSACTION_H
 #define _SWAY_TRANSACTION_H
-#include <wlr/render/wlr_texture.h>
-#include "sway/tree/container.h"
+#include <stdint.h>
 
 /**
  * Transactions enable us to perform atomic layout updates.
@@ -21,6 +20,7 @@
  */
 
 struct sway_transaction_instruction;
+struct sway_view;
 
 /**
  * Find all dirty containers, create and commit a transaction containing them,
diff --git a/include/sway/input/input-manager.h b/include/sway/input/input-manager.h
index aa2f6f19..bde3cf46 100644
--- a/include/sway/input/input-manager.h
+++ b/include/sway/input/input-manager.h
@@ -37,10 +37,10 @@ struct sway_input_manager {
 struct sway_input_manager *input_manager_create(struct sway_server *server);
 
 bool input_manager_has_focus(struct sway_input_manager *input,
-                struct sway_container *container);
+                struct sway_node *node);
 
 void input_manager_set_focus(struct sway_input_manager *input,
-                struct sway_container *container);
+                struct sway_node *node);
 
 void input_manager_configure_xcursor(struct sway_input_manager *input);
 
diff --git a/include/sway/input/seat.h b/include/sway/input/seat.h
index 5c404ecd..8a7e5450 100644
--- a/include/sway/input/seat.h
+++ b/include/sway/input/seat.h
@@ -13,9 +13,9 @@ struct sway_seat_device {
         struct wl_list link; // sway_seat::devices
 };
 
-struct sway_seat_container {
+struct sway_seat_node {
         struct sway_seat *seat;
-        struct sway_container *container;
+        struct sway_node *node;
 
         struct wl_list link; // sway_seat::focus_stack
 
@@ -76,7 +76,7 @@ struct sway_seat {
         uint32_t last_button_serial;
 
         struct wl_listener focus_destroy;
-        struct wl_listener new_container;
+        struct wl_listener new_node;
         struct wl_listener new_drag_icon;
 
         struct wl_list devices; // sway_seat_device::link
@@ -100,10 +100,10 @@ void seat_remove_device(struct sway_seat *seat,
 
 void seat_configure_xcursor(struct sway_seat *seat);
 
-void seat_set_focus(struct sway_seat *seat, struct sway_container *container);
+void seat_set_focus(struct sway_seat *seat, struct sway_node *node);
 
 void seat_set_focus_warp(struct sway_seat *seat,
-                struct sway_container *container, bool warp, bool notify);
+                struct sway_node *node, bool warp, bool notify);
 
 void seat_set_focus_surface(struct sway_seat *seat,
                 struct wlr_surface *surface, bool unfocus);
@@ -114,7 +114,11 @@ void seat_set_focus_layer(struct sway_seat *seat,
 void seat_set_exclusive_client(struct sway_seat *seat,
                 struct wl_client *client);
 
-struct sway_container *seat_get_focus(struct sway_seat *seat);
+struct sway_node *seat_get_focus(struct sway_seat *seat);
+
+struct sway_workspace *seat_get_focused_workspace(struct sway_seat *seat);
+
+struct sway_container *seat_get_focused_container(struct sway_seat *seat);
 
 /**
  * Return the last container to be focused for the seat (or the most recently
@@ -125,32 +129,31 @@ struct sway_container *seat_get_focus(struct sway_seat *seat);
  * is destroyed, or focus moves to a container with children and we need to
  * descend into the next leaf in focus order.
  */
-struct sway_container *seat_get_focus_inactive(struct sway_seat *seat,
-                struct sway_container *container);
+struct sway_node *seat_get_focus_inactive(struct sway_seat *seat,
+                struct sway_node *node);
 
 struct sway_container *seat_get_focus_inactive_tiling(struct sway_seat *seat,
-                struct sway_container *container);
+                struct sway_workspace *workspace);
 
 /**
  * Descend into the focus stack to find the focus-inactive view. Useful for
  * container placement when they change position in the tree.
  */
 struct sway_container *seat_get_focus_inactive_view(struct sway_seat *seat,
-                struct sway_container *container);
+                struct sway_node *ancestor);
 
 /**
  * Return the immediate child of container which was most recently focused.
  */
-struct sway_container *seat_get_active_child(struct sway_seat *seat,
-                struct sway_container *container);
+struct sway_node *seat_get_active_child(struct sway_seat *seat,
+                struct sway_node *parent);
 
 /**
  * Iterate over the focus-inactive children of the container calling the
  * function on each.
  */
-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);
+void seat_for_each_node(struct sway_seat *seat,
+                void (*f)(struct sway_node *node, void *data), void *data);
 
 void seat_apply_config(struct sway_seat *seat, struct seat_config *seat_config);
 
@@ -173,7 +176,7 @@ void seat_begin_resize_tiling(struct sway_seat *seat,
                 struct sway_container *con, uint32_t button, enum wlr_edges edge);
 
 struct sway_container *seat_get_focus_inactive_floating(struct sway_seat *seat,
-                struct sway_container *container);
+                struct sway_workspace *workspace);
 
 void seat_end_mouse_operation(struct sway_seat *seat);
 
diff --git a/include/sway/ipc-json.h b/include/sway/ipc-json.h
index eaaa2164..fef243e3 100644
--- a/include/sway/ipc-json.h
+++ b/include/sway/ipc-json.h
@@ -7,8 +7,8 @@
 json_object *ipc_json_get_version();
 
 json_object *ipc_json_describe_disabled_output(struct sway_output *o);
-json_object *ipc_json_describe_container(struct sway_container *c);
-json_object *ipc_json_describe_container_recursive(struct sway_container *c);
+json_object *ipc_json_describe_node(struct sway_node *node);
+json_object *ipc_json_describe_node_recursive(struct sway_node *node);
 json_object *ipc_json_describe_input(struct sway_input_device *device);
 json_object *ipc_json_describe_seat(struct sway_seat *seat);
 json_object *ipc_json_describe_bar_config(struct bar_config *bar);
diff --git a/include/sway/ipc-server.h b/include/sway/ipc-server.h
index 4b6d0e25..80180ec4 100644
--- a/include/sway/ipc-server.h
+++ b/include/sway/ipc-server.h
@@ -11,8 +11,8 @@ void ipc_init(struct sway_server *server);
 
 struct sockaddr_un *ipc_user_sockaddr(void);
 
-void ipc_event_workspace(struct sway_container *old,
-                struct sway_container *new, const char *change);
+void ipc_event_workspace(struct sway_workspace *old,
+                struct sway_workspace *new, const char *change);
 void ipc_event_window(struct sway_container *window, const char *change);
 void ipc_event_barconfig_update(struct bar_config *bar);
 void ipc_event_mode(const char *mode, bool pango);
diff --git a/include/sway/output.h b/include/sway/output.h
index 651fdfe7..540ed8a0 100644
--- a/include/sway/output.h
+++ b/include/sway/output.h
@@ -6,14 +6,20 @@
 #include <wlr/types/wlr_box.h>
 #include <wlr/types/wlr_output.h>
 #include "config.h"
+#include "sway/tree/node.h"
 #include "sway/tree/view.h"
 
 struct sway_server;
 struct sway_container;
 
+struct sway_output_state {
+        list_t *workspaces;
+        struct sway_workspace *active_workspace;
+};
+
 struct sway_output {
+        struct sway_node node;
         struct wlr_output *wlr_output;
-        struct sway_container *swayc;
         struct sway_server *server;
 
         struct wl_list layers[4]; // sway_layer_surface::link
@@ -22,11 +28,15 @@ struct sway_output {
         struct timespec last_frame;
         struct wlr_output_damage *damage;
 
+        bool enabled;
+        list_t *workspaces;
+
+        struct sway_output_state current;
+
         struct wl_listener destroy;
         struct wl_listener mode;
         struct wl_listener transform;
         struct wl_listener scale;
-
         struct wl_listener damage_destroy;
         struct wl_listener damage_frame;
 
@@ -39,13 +49,19 @@ struct sway_output {
         } events;
 };
 
-struct sway_container *output_create(struct sway_output *sway_output);
+struct sway_output *output_create(struct wlr_output *wlr_output);
+
+void output_destroy(struct sway_output *output);
+
+void output_begin_destroy(struct sway_output *output);
 
-void output_destroy(struct sway_container *output);
+struct sway_output *output_from_wlr_output(struct wlr_output *output);
 
-void output_begin_destroy(struct sway_container *output);
+struct sway_output *output_get_in_direction(struct sway_output *reference,
+                enum movement_direction direction);
 
-struct sway_container *output_from_wlr_output(struct wlr_output *output);
+void output_add_workspace(struct sway_output *output,
+                struct sway_workspace *workspace);
 
 typedef void (*sway_surface_iterator_func_t)(struct sway_output *output,
         struct wlr_surface *surface, struct wlr_box *box, float rotation,
@@ -64,15 +80,19 @@ void output_damage_box(struct sway_output *output, struct wlr_box *box);
 void output_damage_whole_container(struct sway_output *output,
         struct sway_container *con);
 
-struct sway_container *output_by_name(const char *name);
+struct sway_output *output_by_name(const char *name);
 
-void output_sort_workspaces(struct sway_container *output);
+void output_sort_workspaces(struct sway_output *output);
 
-void output_enable(struct sway_output *output);
+struct output_config *output_find_config(struct sway_output *output);
+
+void output_enable(struct sway_output *output, struct output_config *oc);
+
+void output_disable(struct sway_output *output);
 
 bool output_has_opaque_overlay_layer_surface(struct sway_output *output);
 
-struct sway_container *output_get_active_workspace(struct sway_output *output);
+struct sway_workspace *output_get_active_workspace(struct sway_output *output);
 
 void output_render(struct sway_output *output, struct timespec *when,
         pixman_region32_t *damage);
@@ -103,16 +123,23 @@ 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_workspace(struct sway_output *output,
+                void (*f)(struct sway_workspace *ws, void *data), void *data);
 
-void output_for_each_container(struct sway_container *output,
+void output_for_each_container(struct sway_output *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_workspace *output_find_workspace(struct sway_output *output,
+                bool (*test)(struct sway_workspace *ws, void *data), void *data);
 
-struct sway_container *output_find_container(struct sway_container *output,
+struct sway_container *output_find_container(struct sway_output *output,
                 bool (*test)(struct sway_container *con, void *data), void *data);
 
+void output_get_box(struct sway_output *output, struct wlr_box *box);
+
+enum sway_container_layout output_get_default_layout(
+                struct sway_output *output);
+
+void output_add_listeners(struct sway_output *output);
+
 #endif
diff --git a/include/sway/server.h b/include/sway/server.h
index 1e20f2c8..07e0949a 100644
--- a/include/sway/server.h
+++ b/include/sway/server.h
@@ -56,7 +56,7 @@ struct sway_server {
 
         size_t txn_timeout_ms;
         list_t *transactions;
-        list_t *dirty_containers;
+        list_t *dirty_nodes;
 };
 
 struct sway_server server;
diff --git a/include/sway/tree/arrange.h b/include/sway/tree/arrange.h
index f47e8db5..06a2279c 100644
--- a/include/sway/tree/arrange.h
+++ b/include/sway/tree/arrange.h
@@ -1,16 +1,19 @@
 #ifndef _SWAY_ARRANGE_H
 #define _SWAY_ARRANGE_H
 
+struct sway_output;
+struct sway_workspace;
 struct sway_container;
+struct sway_node;
 
 void arrange_container(struct sway_container *container);
 
-void arrange_workspace(struct sway_container *workspace);
+void arrange_workspace(struct sway_workspace *workspace);
 
-void arrange_output(struct sway_container *output);
+void arrange_output(struct sway_output *output);
 
 void arrange_root(void);
 
-void arrange_windows(struct sway_container *container);
+void arrange_node(struct sway_node *node);
 
 #endif
diff --git a/include/sway/tree/container.h b/include/sway/tree/container.h
index e4071cfe..c51425c9 100644
--- a/include/sway/tree/container.h
+++ b/include/sway/tree/container.h
@@ -5,8 +5,7 @@
 #include <wlr/types/wlr_box.h>
 #include <wlr/types/wlr_surface.h>
 #include "list.h"
-
-extern struct sway_container root_container;
+#include "sway/tree/node.h"
 
 struct sway_view;
 struct sway_seat;
@@ -17,23 +16,6 @@ struct sway_seat;
 #define TITLEBAR_H_PADDING 3
 #define TITLEBAR_V_PADDING 4
 
-/**
- * Different kinds of containers.
- *
- * This enum is in order. A container will never be inside of a container below
- * it on this list.
- */
-enum sway_container_type {
-        C_ROOT,
-        C_OUTPUT,
-        C_WORKSPACE,
-        C_CONTAINER,
-        C_VIEW,
-
-        // Keep last
-        C_TYPES,
-};
-
 enum sway_container_layout {
         L_NONE,
         L_HORIZ,
@@ -57,18 +39,14 @@ enum movement_direction;
 enum wlr_direction;
 
 struct sway_container_state {
-        // Container/swayc properties
+        // Container properties
         enum sway_container_layout layout;
-        double swayc_x, swayc_y;
-        double swayc_width, swayc_height;
+        double con_x, con_y;
+        double con_width, con_height;
 
         bool is_fullscreen;
 
-        bool has_gaps;
-        double current_gaps;
-        double gaps_inner;
-        double gaps_outer;
-
+        struct sway_workspace *workspace;
         struct sway_container *parent;
         list_t *children;
 
@@ -86,35 +64,19 @@ struct sway_container_state {
         bool border_left;
         bool border_right;
         bool using_csd;
-
-        // Workspace properties
-        struct sway_container *ws_fullscreen;
-        list_t *ws_floating;
 };
 
 struct sway_container {
-        union {
-                // TODO: Encapsulate state for other node types as well like C_CONTAINER
-                struct sway_root *sway_root;
-                struct sway_output *sway_output;
-                struct sway_workspace *sway_workspace;
-                struct sway_view *sway_view;
-        };
-
-        /**
-         * A unique ID to identify this container. Primarily used in the
-         * get_tree JSON output.
-         */
-        size_t id;
+        struct sway_node node;
+        struct sway_view *view;
 
         // The pending state is the main container properties, and the current state is in the below struct.
         // This means most places of the code can refer to the main variables (pending state) and it'll just work.
         struct sway_container_state current;
 
-        char *name;            // The view's title (unformatted)
+        char *title;           // The view's title (unformatted)
         char *formatted_title; // The title displayed in the title bar
 
-        enum sway_container_type type;
         enum sway_container_layout layout;
         enum sway_container_layout prev_split_layout;
 
@@ -132,14 +94,13 @@ struct sway_container {
 
         // The gaps currently applied to the container.
         double current_gaps;
-
         bool has_gaps;
         double gaps_inner;
         double gaps_outer;
 
-        list_t *children;
-
-        struct sway_container *parent;
+        struct sway_workspace *workspace; // NULL when hidden in the scratchpad
+        struct sway_container *parent;    // NULL if container in root of workspace
+        list_t *children;                 // struct sway_container
 
         // Outputs currently being intersected
         list_t *outputs; // struct sway_output
@@ -157,42 +118,17 @@ struct sway_container {
         struct wlr_texture *title_urgent;
         size_t title_height;
 
-        // The number of transactions which reference this container.
-        size_t ntxnrefs;
-
-        // If this container is a view and is waiting for the client to respond to a
-        // configure then this will be populated, otherwise NULL.
-        struct sway_transaction_instruction *instruction;
-
-        bool destroying;
-
-        // If true, indicates that the container has pending state that differs from
-        // the current.
-        bool dirty;
-
         struct {
                 struct wl_signal destroy;
         } events;
 };
 
-struct sway_container *container_create(enum sway_container_type type);
-
-const char *container_type_to_str(enum sway_container_type type);
-
-/*
- * Create a new view container. A view can be a child of a workspace container
- * or a container container and are rendered in the order and structure of
- * how they are attached to the tree.
- */
-struct sway_container *container_view_create(
-                struct sway_container *sibling, struct sway_view *sway_view);
+struct sway_container *container_create(struct sway_view *view);
 
 void container_destroy(struct sway_container *con);
 
 void container_begin_destroy(struct sway_container *con);
 
-struct sway_container *container_close(struct sway_container *container);
-
 /**
  * Search a container's descendants a container based on test criteria. Returns
  * the first container that passes the test.
@@ -201,22 +137,16 @@ struct sway_container *container_find_child(struct sway_container *container,
                 bool (*test)(struct sway_container *view, void *data), void *data);
 
 /**
- * Finds a parent container with the given struct sway_containerype.
- */
-struct sway_container *container_parent(struct sway_container *container,
-                enum sway_container_type type);
-
-/**
  * Find a container at the given coordinates. Returns the the surface and
  * surface-local coordinates of the given layout coordinates if the container
  * is a view and the view contains a surface at those coordinates.
  */
-struct sway_container *container_at(struct sway_container *workspace,
+struct sway_container *container_at(struct sway_workspace *workspace,
                 double lx, double ly, struct wlr_surface **surface,
                 double *sx, double *sy);
 
 struct sway_container *tiling_container_at(
-                struct sway_container *con, double lx, double ly,
+                struct sway_node *parent, double lx, double ly,
                 struct wlr_surface **surface, double *sx, double *sy);
 
 void container_for_each_child(struct sway_container *container,
@@ -228,16 +158,11 @@ void container_for_each_child(struct sway_container *container,
 bool container_has_ancestor(struct sway_container *container,
                 struct sway_container *ancestor);
 
-int container_count_descendants_of_type(struct sway_container *con,
-                enum sway_container_type type);
-
-void container_create_notify(struct sway_container *container);
-
 void container_update_textures_recursive(struct sway_container *con);
 
 void container_damage_whole(struct sway_container *container);
 
-struct sway_container *container_reap_empty(struct sway_container *con);
+void container_reap_empty(struct sway_container *con);
 
 struct sway_container *container_flatten(struct sway_container *container);
 
@@ -248,11 +173,10 @@ void container_update_title_textures(struct sway_container *container);
  */
 void container_calculate_title_height(struct sway_container *container);
 
-/**
- * Notify a container that a tree modification has changed in its children,
- * so the container can update its tree representation.
- */
-void container_notify_subtree_changed(struct sway_container *container);
+size_t container_build_representation(enum sway_container_layout layout,
+                list_t *children, char *buffer);
+
+void container_update_representation(struct sway_container *container);
 
 /**
  * Return the height of a regular title bar.
@@ -288,8 +212,7 @@ void container_floating_translate(struct sway_container *con,
 /**
  * Choose an output for the floating container's new position.
  */
-struct sway_container *container_floating_find_output(
-                struct sway_container *con);
+struct sway_output *container_floating_find_output(struct sway_container *con);
 
 /**
  * Move a floating container to a new layout-local position.
@@ -302,12 +225,6 @@ void container_floating_move_to(struct sway_container *con,
  */
 void container_floating_move_to_center(struct sway_container *con);
 
-/**
- * Mark a container as dirty if it isn't already. Dirty containers will be
- * included in the next transaction then unmarked as dirty.
- */
-void container_set_dirty(struct sway_container *container);
-
 bool container_has_urgent_child(struct sway_container *container);
 
 /**
@@ -342,10 +259,18 @@ void container_remove_gaps(struct sway_container *container);
 
 void container_add_gaps(struct sway_container *container);
 
+enum sway_container_layout container_parent_layout(struct sway_container *con);
+
+enum sway_container_layout container_current_parent_layout(
+                struct sway_container *con);
+
+list_t *container_get_siblings(const struct sway_container *container);
+
 int container_sibling_index(const struct sway_container *child);
 
-void container_handle_fullscreen_reparent(struct sway_container *con,
-                struct sway_container *old_parent);
+list_t *container_get_current_siblings(struct sway_container *container);
+
+void container_handle_fullscreen_reparent(struct sway_container *con);
 
 void container_add_child(struct sway_container *parent,
                 struct sway_container *child);
@@ -353,19 +278,16 @@ void container_add_child(struct sway_container *parent,
 void container_insert_child(struct sway_container *parent,
                 struct sway_container *child, int i);
 
-struct sway_container *container_add_sibling(struct sway_container *parent,
-                struct sway_container *child);
+void container_add_sibling(struct sway_container *parent,
+                struct sway_container *child, int offset);
 
-struct sway_container *container_remove_child(struct sway_container *child);
+void container_detach(struct sway_container *child);
 
-struct sway_container *container_replace_child(struct sway_container *child,
-                struct sway_container *new_child);
+void container_replace(struct sway_container *container,
+                struct sway_container *replacement);
 
 bool sway_dir_to_wlr(enum movement_direction dir, enum wlr_direction *out);
 
-enum sway_container_layout container_get_default_layout(
-                struct sway_container *con);
-
 struct sway_container *container_split(struct sway_container *child,
                 enum sway_container_layout layout);
 
diff --git a/include/sway/tree/node.h b/include/sway/tree/node.h
new file mode 100644
index 00000000..5b8c1909
--- /dev/null
+++ b/include/sway/tree/node.h
@@ -0,0 +1,74 @@
+#ifndef _SWAY_NODE_H
+#define _SWAY_NODE_H
+#include <stdbool.h>
+#include "list.h"
+
+struct sway_root;
+struct sway_output;
+struct sway_workspace;
+struct sway_container;
+struct sway_transaction_instruction;
+struct wlr_box;
+
+enum sway_node_type {
+        N_ROOT,
+        N_OUTPUT,
+        N_WORKSPACE,
+        N_CONTAINER,
+};
+
+struct sway_node {
+        enum sway_node_type type;
+        union {
+                struct sway_root *sway_root;
+                struct sway_output *sway_output;
+                struct sway_workspace *sway_workspace;
+                struct sway_container *sway_container;
+        };
+
+        /**
+         * A unique ID to identify this node.
+         * Primarily used in the get_tree JSON output.
+         */
+        size_t id;
+
+        struct sway_transaction_instruction *instruction;
+        size_t ntxnrefs;
+        bool destroying;
+
+        // If true, indicates that the container has pending state that differs from
+        // the current.
+        bool dirty;
+
+        struct {
+                struct wl_signal destroy;
+        } events;
+};
+
+void node_init(struct sway_node *node, enum sway_node_type type, void *thing);
+
+const char *node_type_to_str(enum sway_node_type type);
+
+/**
+ * Mark a node as dirty if it isn't already. Dirty nodes will be included in the
+ * next transaction then unmarked as dirty.
+ */
+void node_set_dirty(struct sway_node *node);
+
+bool node_is_view(struct sway_node *node);
+
+char *node_get_name(struct sway_node *node);
+
+void node_get_box(struct sway_node *node, struct wlr_box *box);
+
+struct sway_output *node_get_output(struct sway_node *node);
+
+enum sway_container_layout node_get_layout(struct sway_node *node);
+
+struct sway_node *node_get_parent(struct sway_node *node);
+
+list_t *node_get_children(struct sway_node *node);
+
+bool node_has_ancestor(struct sway_node *node, struct sway_node *ancestor);
+
+#endif
diff --git a/include/sway/tree/root.h b/include/sway/tree/root.h
index ec6516c9..a2d464f9 100644
--- a/include/sway/tree/root.h
+++ b/include/sway/tree/root.h
@@ -5,12 +5,14 @@
 #include <wlr/types/wlr_output_layout.h>
 #include <wlr/render/wlr_texture.h>
 #include "sway/tree/container.h"
+#include "sway/tree/node.h"
 #include "config.h"
 #include "list.h"
 
-extern struct sway_container root_container;
+extern struct sway_root *root;
 
 struct sway_root {
+        struct sway_node node;
         struct wlr_output_layout *output_layout;
 
         struct wl_listener output_layout_change;
@@ -24,17 +26,21 @@ struct sway_root {
         // Includes disabled outputs
         struct wl_list all_outputs; // sway_output::link
 
+        double x, y;
+        double width, height;
+
+        list_t *outputs; // struct sway_output
         list_t *scratchpad; // struct sway_container
         list_t *saved_workspaces; // For when there's no connected outputs
 
         struct {
-                struct wl_signal new_container;
+                struct wl_signal new_node;
         } events;
 };
 
-void root_create(void);
+struct sway_root *root_create(void);
 
-void root_destroy(void);
+void root_destroy(struct sway_root *root);
 
 /**
  * Move a container to the scratchpad.
@@ -56,23 +62,25 @@ void root_scratchpad_show(struct sway_container *con);
  */
 void root_scratchpad_hide(struct sway_container *con);
 
-struct sway_container *root_workspace_for_pid(pid_t pid);
+struct sway_workspace *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 root_for_each_workspace(void (*f)(struct sway_workspace *ws, 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_output *root_find_output(
+                bool (*test)(struct sway_output *output, void *data), void *data);
 
-struct sway_container *root_find_workspace(
-                bool (*test)(struct sway_container *con, void *data), void *data);
+struct sway_workspace *root_find_workspace(
+                bool (*test)(struct sway_workspace *ws, void *data), void *data);
 
 struct sway_container *root_find_container(
                 bool (*test)(struct sway_container *con, void *data), void *data);
 
+void root_get_box(struct sway_root *root, struct wlr_box *box);
+
 #endif
diff --git a/include/sway/tree/view.h b/include/sway/tree/view.h
index 30d3e742..439dc1bf 100644
--- a/include/sway/tree/view.h
+++ b/include/sway/tree/view.h
@@ -58,7 +58,7 @@ struct sway_view {
         enum sway_view_type type;
         const struct sway_view_impl *impl;
 
-        struct sway_container *swayc; // NULL for unmapped views
+        struct sway_container *container; // NULL if unmapped and transactions finished
         struct wlr_surface *surface; // NULL for unmapped views
 
         // Geometry of the view itself (excludes borders) in layout coordinates
@@ -254,7 +254,7 @@ uint32_t view_configure(struct sway_view *view, double lx, double ly, int width,
         int height);
 
 /**
- * Configure the view's position and size based on the swayc's position and
+ * Configure the view's position and size based on the container's position and
  * size, taking borders into consideration.
  */
 void view_autoconfigure(struct sway_view *view);
diff --git a/include/sway/tree/workspace.h b/include/sway/tree/workspace.h
index 04325919..af9a071a 100644
--- a/include/sway/tree/workspace.h
+++ b/include/sway/tree/workspace.h
@@ -3,66 +3,98 @@
 
 #include <stdbool.h>
 #include "sway/tree/container.h"
+#include "sway/tree/node.h"
 
 struct sway_view;
 
+struct sway_workspace_state {
+        struct sway_container *fullscreen;
+        double x, y;
+        int width, height;
+        enum sway_container_layout layout;
+        struct sway_output *output;
+        list_t *floating;
+        list_t *tiling;
+
+        struct sway_container *focused_inactive_child;
+        bool focused;
+};
+
 struct sway_workspace {
-        struct sway_container *swayc;
+        struct sway_node node;
         struct sway_container *fullscreen;
-        list_t *floating; // struct sway_container
+
+        char *name;
+        char *representation;
+
+        double x, y;
+        int width, height;
+        enum sway_container_layout layout;
+        enum sway_container_layout prev_split_layout;
+
+        double current_gaps;
+        bool has_gaps;
+        double gaps_inner;
+        double gaps_outer;
+
+        struct sway_output *output; // NULL if no outputs are connected
+        list_t *floating;           // struct sway_container
+        list_t *tiling;             // struct sway_container
         list_t *output_priority;
         bool urgent;
+
+        struct sway_workspace_state current;
 };
 
 extern char *prev_workspace_name;
 
-struct sway_container *workspace_get_initial_output(const char *name);
+struct sway_output *workspace_get_initial_output(const char *name);
 
-struct sway_container *workspace_create(struct sway_container *output,
+struct sway_workspace *workspace_create(struct sway_output *output,
                 const char *name);
 
-void workspace_destroy(struct sway_container *workspace);
+void workspace_destroy(struct sway_workspace *workspace);
 
-void workspace_begin_destroy(struct sway_container *workspace);
+void workspace_begin_destroy(struct sway_workspace *workspace);
 
-void workspace_consider_destroy(struct sway_container *ws);
+void workspace_consider_destroy(struct sway_workspace *ws);
 
 char *workspace_next_name(const char *output_name);
 
-bool workspace_switch(struct sway_container *workspace,
+bool workspace_switch(struct sway_workspace *workspace,
                 bool no_auto_back_and_forth);
 
-struct sway_container *workspace_by_number(const char* name);
+struct sway_workspace *workspace_by_number(const char* name);
 
-struct sway_container *workspace_by_name(const char*);
+struct sway_workspace *workspace_by_name(const char*);
 
-struct sway_container *workspace_output_next(struct sway_container *current);
+struct sway_workspace *workspace_output_next(struct sway_workspace *current);
 
-struct sway_container *workspace_next(struct sway_container *current);
+struct sway_workspace *workspace_next(struct sway_workspace *current);
 
-struct sway_container *workspace_output_prev(struct sway_container *current);
+struct sway_workspace *workspace_output_prev(struct sway_workspace *current);
 
-struct sway_container *workspace_prev(struct sway_container *current);
+struct sway_workspace *workspace_prev(struct sway_workspace *current);
 
-bool workspace_is_visible(struct sway_container *ws);
+bool workspace_is_visible(struct sway_workspace *ws);
 
-bool workspace_is_empty(struct sway_container *ws);
+bool workspace_is_empty(struct sway_workspace *ws);
 
-void workspace_output_raise_priority(struct sway_container *workspace,
-                struct sway_container *old_output, struct sway_container *new_output);
+void workspace_output_raise_priority(struct sway_workspace *workspace,
+                struct sway_output *old_output, struct sway_output *new_output);
 
-void workspace_output_add_priority(struct sway_container *workspace,
-                struct sway_container *output);
+void workspace_output_add_priority(struct sway_workspace *workspace,
+                struct sway_output *output);
 
-struct sway_container *workspace_output_get_highest_available(
-                struct sway_container *ws, struct sway_container *exclude);
+struct sway_output *workspace_output_get_highest_available(
+                struct sway_workspace *ws, struct sway_output *exclude);
 
-void workspace_detect_urgent(struct sway_container *workspace);
+void workspace_detect_urgent(struct sway_workspace *workspace);
 
-void workspace_for_each_container(struct sway_container *ws,
+void workspace_for_each_container(struct sway_workspace *ws,
                 void (*f)(struct sway_container *con, void *data), void *data);
 
-struct sway_container *workspace_find_container(struct sway_container *ws,
+struct sway_container *workspace_find_container(struct sway_workspace *ws,
                 bool (*test)(struct sway_container *con, void *data), void *data);
 
 /**
@@ -70,13 +102,28 @@ struct sway_container *workspace_find_container(struct sway_container *ws,
  * The new container will be the only direct tiling child of the workspace.
  * The new container is returned.
  */
-struct sway_container *workspace_wrap_children(struct sway_container *ws);
+struct sway_container *workspace_wrap_children(struct sway_workspace *ws);
 
-void workspace_add_floating(struct sway_container *workspace,
+void workspace_detach(struct sway_workspace *workspace);
+
+void workspace_add_tiling(struct sway_workspace *workspace,
+                struct sway_container *con);
+
+void workspace_add_floating(struct sway_workspace *workspace,
                 struct sway_container *con);
 
-void workspace_remove_gaps(struct sway_container *ws);
+void workspace_insert_tiling(struct sway_workspace *workspace,
+                struct sway_container *con, int index);
+
+void workspace_remove_gaps(struct sway_workspace *ws);
+
+void workspace_add_gaps(struct sway_workspace *ws);
+
+struct sway_container *workspace_split(struct sway_workspace *workspace,
+                enum sway_container_layout layout);
+
+void workspace_update_representation(struct sway_workspace *ws);
 
-void workspace_add_gaps(struct sway_container *ws);
+void workspace_get_box(struct sway_workspace *workspace, struct wlr_box *box);
 
 #endif