Destroy empty workspaces when moving away

include/sway/tree/container.h

@@ -99,8 +99,13 @@ struct sway_container *container_view_create(
 
 struct sway_container *container_output_destroy(struct sway_container *output);
 
+struct sway_container *container_workspace_destroy(
+		struct sway_container *workspace);
+
 struct sway_container *container_view_destroy(struct sway_container *view);
 
+void container_destroy(struct sway_container *cont);
+
 struct sway_container *container_set_layout(struct sway_container *container,
 		enum sway_container_layout layout);
 
@@ -140,4 +145,7 @@ void container_for_each_descendant_bfs(struct sway_container *container,
 void container_for_each_descendant_dfs(struct sway_container *container,
 		void (*f)(struct sway_container *container, void *data), void *data);
 
+bool container_has_anscestor(struct sway_container *descendant,
+		struct sway_container *anscestor);
+
 #endif

include/sway/tree/layout.h

@@ -39,6 +39,9 @@ struct sway_container *container_add_sibling(struct sway_container *parent,
 
 struct sway_container *container_remove_child(struct sway_container *child);
 
+void container_move_to(struct sway_container* container,
+		struct sway_container* destination);
+
 enum sway_container_layout container_get_default_layout(struct sway_container *output);
 
 void container_sort_workspaces(struct sway_container *output);

sway/input/seat.c

@@ -8,6 +8,7 @@
 #include "sway/input/keyboard.h"
 #include "sway/ipc-server.h"
 #include "sway/output.h"
+#include "sway/tree/container.h"
 #include "sway/tree/view.h"
 #include "log.h"
 
@@ -331,6 +332,9 @@ void sway_seat_set_focus(struct sway_seat *seat, struct sway_container *containe
 		if (last_ws) {
 			wlr_log(L_DEBUG, "sending workspace event");
 			ipc_event_workspace(last_ws, container, "focus");
+			if (last_ws->children->length == 0) {
+				container_workspace_destroy(last_ws);
+			}
 		}
 	}
 

sway/tree/container.c

@@ -58,7 +58,7 @@ static struct sway_container *container_create(enum sway_container_type type) {
 	return c;
 }
 
-static void container_destroy(struct sway_container *cont) {
+void container_destroy(struct sway_container *cont) {
 	if (cont == NULL) {
 		return;
 	}
@@ -203,8 +203,7 @@ struct sway_container *container_view_create(struct sway_container *sibling,
 }
 
 struct sway_container *container_output_destroy(struct sway_container *output) {
-	if (!sway_assert(output,
-				"null output passed to container_output_destroy")) {
+	if (!sway_assert(output, "cannot destroy null output")) {
 		return NULL;
 	}
 
@@ -236,6 +235,45 @@ struct sway_container *container_output_destroy(struct sway_container *output) {
 	return &root_container;
 }
 
+struct sway_container *container_workspace_destroy(
+		struct sway_container *workspace) {
+	if (!sway_assert(workspace, "cannot destroy null workspace")) {
+		return NULL;
+	}
+
+	// Do not destroy this if it's the last workspace on this output
+	struct sway_container *output = container_parent(workspace, C_OUTPUT);
+	if (output && output->children->length == 1) {
+		return NULL;
+	}
+
+	struct sway_container *parent = workspace->parent;
+	if (workspace->children->length == 0) {
+		// destroy the WS if there are no children (TODO check for floating)
+		wlr_log(L_DEBUG, "destroying workspace '%s'", workspace->name);
+		ipc_event_workspace(workspace, NULL, "empty");
+	} else {
+		// Move children to a different workspace on this output
+		struct sway_container *new_workspace = NULL;
+		// TODO move floating
+		for (int i = 0; i < output->children->length; i++) {
+			if (output->children->items[i] != workspace) {
+				new_workspace = output->children->items[i];
+				break;
+			}
+		}
+
+		wlr_log(L_DEBUG, "moving children to different workspace '%s' -> '%s'",
+			workspace->name, new_workspace->name);
+		for (int i = 0; i < workspace->children->length; i++) {
+			container_move_to(workspace->children->items[i], new_workspace);
+		}
+	}
+
+	container_destroy(workspace);
+	return parent;
+}
+
 struct sway_container *container_view_destroy(struct sway_container *view) {
 	if (!view) {
 		return NULL;
@@ -438,3 +476,14 @@ void container_for_each_descendant_bfs(struct sway_container *con,
 		list_cat(queue, current->children);
 	}
 }
+
+bool container_has_anscestor(struct sway_container *descendant,
+		struct sway_container *anscestor) {
+	while (descendant->type != C_ROOT) {
+		descendant = descendant->parent;
+		if (descendant == anscestor) {
+			return true;
+		}
+	}
+	return false;
+}

sway/tree/layout.c

@@ -11,6 +11,7 @@
 #include "sway/output.h"
 #include "sway/tree/view.h"
 #include "sway/input/seat.h"
+#include "sway/ipc-server.h"
 #include "list.h"
 #include "log.h"
 
@@ -121,6 +122,42 @@ struct sway_container *container_remove_child(struct sway_container *child) {
 	return parent;
 }
 
+struct sway_container *container_reap_empty(struct sway_container *container) {
+	if (!sway_assert(container, "reaping null container")) {
+		return NULL;
+	}
+	while (container->children->length == 0 && container->type == C_CONTAINER) {
+		wlr_log(L_DEBUG, "Container: Destroying container '%p'", container);
+		struct sway_container *parent = container->parent;
+		container_destroy(container);
+		container = parent;
+	}
+	return container;
+}
+
+void container_move_to(struct sway_container* container,
+		struct sway_container* destination) {
+	if (container == destination
+			|| container_has_anscestor(container, destination)) {
+		return;
+	}
+	struct sway_container *old_parent = container_remove_child(container);
+	container->width = container->height = 0;
+	struct sway_container *new_parent =
+		container_add_sibling(destination, container);
+	if (destination->type == C_WORKSPACE) {
+		// If the workspace only has one child after adding one, it
+		// means that the workspace was just initialized.
+		// TODO: Consider floating views in this test
+		if (destination->children->length == 1) {
+			ipc_event_workspace(NULL, destination, "init");
+		}
+	}
+	old_parent = container_reap_empty(old_parent);
+	arrange_windows(old_parent, -1, -1);
+	arrange_windows(new_parent, -1, -1);
+}
+
 enum sway_container_layout container_get_default_layout(
 		struct sway_container *output) {
 	/* TODO WLR