make walls vec optional

src/mock.rs

@@ -529,7 +529,7 @@ pub fn room() -> Room {
             position: Position { x: 8, y: 7 },
             id: "undefined".to_string(),
         }],
-        walls: vec![],
+        walls: None,
     }
 }
 
@@ -828,7 +828,7 @@ pub fn game_default() -> Game {
             items: vec![],
             exits: vec![],
             endings: vec![],
-            walls: vec![],
+            walls: None,
         }],
         tiles: vec![self::tile_default()],
         sprites: vec![

src/room.rs

@@ -23,7 +23,7 @@ pub struct Room {
     pub exits: Vec<ExitInstance>,
     pub endings: Vec<Instance>,
     /// old method of handling walls - a comma-separated list of tile IDs
-    pub walls: Vec<String>,
+    pub walls: Option<Vec<String>>,
 }
 
 impl Room {
@@ -32,10 +32,10 @@ impl Room {
     }
 
     fn wall_line(&self) -> String {
-        if self.walls.is_empty() {
-            "".to_string()
+        if let Some(walls) = &self.walls {
+            optional_data_line("WAL", Some(walls.join(",")))
         } else {
-            optional_data_line("WAL", Some(self.walls.join(",")))
+            "".to_string()
         }
     }
 
@@ -58,7 +58,7 @@ impl From<String> for Room {
         let mut items: Vec<Instance> = Vec::new();
         let mut exits: Vec<ExitInstance> = Vec::new();
         let mut endings: Vec<Instance> = Vec::new();
-        let mut walls: Vec<String> = Vec::new();
+        let mut walls = None;
 
         loop {
             let last_line = lines.pop().unwrap();
@@ -66,7 +66,7 @@ impl From<String> for Room {
             if last_line.starts_with("WAL") {
                 let last_line = last_line.replace("WAL ", "");
                 let ids: Vec<&str> = last_line.split(',').collect();
-                walls = ids.iter().map(|&id| id.to_string()).collect();
+                walls = Some(ids.iter().map(|&id| id.to_string()).collect());
             } else if last_line.starts_with("NAME") {
                 name = Some(last_line.replace("NAME ", "").to_string());
             } else if last_line.starts_with("PAL") {
@@ -258,6 +258,6 @@ mod test {
     fn room_walls_array() {
         let output = Room::from(include_str!("test-resources/room-with-walls").to_string());
 
-        assert_eq!(output.walls, vec!["a".to_string(), "f".to_string()]);
+        assert_eq!(output.walls, Some(vec!["a".to_string(), "f".to_string()]));
     }
 }