fix worlds with boxes not saving & loading due to cyclic references.

js/save_load.mjs

@@ -20,7 +20,7 @@ save_button.onclick = _ => {
 
 function generate_save_data () {
 	const root = world.get_root();
-	return btoa(JSON.stringify(root));
+	return btoa(world.to_json(root));
 }
 
 function save_text (filename, text) {
@@ -45,7 +45,7 @@ load_button.onclick = _ => {
 }
 
 function load_from_text (text) {
-	const data = JSON.parse(atob(text));
+	const data = world.from_json(atob(text));
 	world.replace_root(data);
 }
 

js/world.mjs

@@ -42,9 +42,39 @@ export function out_of_bounds (x, y) {
 		y < 0 || y >= BOX_SIZE
 }
 
-export function replace_root (new_world) {
-	// maybe unnecessary to go over each tile instead of just each column.
+export function for_each_tile (world, callback) {
 	iter_2d(range(0, BOX_SIZE - 1), (x, y) => {
-		set_tile(world, x, y, get_tile(new_world, x, y));
+		callback(x, y, get_tile(world, x, y), world);
 	});
 }
+
+export function replace_root (new_world) {
+	// maybe unnecessary to go over each tile instead of just each column.
+	for_each_tile(new_world, (x, y, tile) => {
+		set_tile(world, x, y, tile);
+	});
+}
+
+export function to_json () {
+	return JSON.stringify(world, (key, value) => {
+		if (key === "parent") return undefined;
+		return value;
+	});
+}
+
+function reconstruct_parent (world, parent) {
+	for_each_tile(world, (x, y, tile) => {
+		if (tile.type !== "box") return;
+		tile.parent = parent;
+		reconstruct_parent(tile.box, world);
+	});
+}
+
+export function from_json (json) {
+	const result = JSON.parse(json);
+	for_each_tile(result, (x, y, tile) => {
+		if (tile.type !== "box") return;
+		reconstruct_parent(tile.box, result);
+	});
+	return result;
+}