make tile wall "optional" (specified or not); tile colour id

src/tile.rs

@@ -6,14 +6,31 @@ use crate::mock;
 pub struct Tile {
     pub id: u64,
     pub name: Option<String>,
-    pub wall: bool,
+    pub wall: Option<bool>, // this is "optional" in that a tile can have `WAL true|false` or neither
     pub animation_frames: Vec<Image>,
+    pub colour_id: Option<u64>,
 }
 
 impl Tile {
     fn name_line(&self) -> String {
         optional_data_line("NAME", self.name.as_ref())
     }
+
+    fn wall_line(&self) -> String {
+        if self.wall.is_some() {
+            format!("\nWAL {}", self.wall.unwrap())
+        } else {
+            "".to_string()
+        }
+    }
+
+    fn colour_line(&self) -> String {
+        if self.colour_id.is_some() {
+            format!("\nCOL {}", self.colour_id.unwrap())
+        } else {
+            "".to_string()
+        }
+    }
 }
 
 impl From<String> for Tile {
@@ -23,31 +40,32 @@ impl From<String> for Tile {
 
         let id = from_base36(&lines[0].replace("TIL ", ""));
 
-        let last_line = lines.pop().unwrap();
-        let wall = match last_line == "WAL true" {
-            true => true,
-            false => {
-                lines.push(last_line);
-                false
-            }
-        };
+        let mut wall = None;
+        let mut name = None;
+        let mut colour_id = None;
 
+        loop {
             let last_line = lines.pop().unwrap();
-        let name = match last_line.starts_with("NAME") {
-            true => Some(last_line.replace("NAME ", "").to_string()),
-            false => {
+
+            if last_line.starts_with("WAL") {
+                wall = Some(last_line.ends_with("true"));
+            } else if last_line.starts_with("NAME") {
+                name = Some(last_line.replace("NAME ", "").to_string());
+            } else if last_line.starts_with("COL") {
+                colour_id = Some(last_line.replace("COL ", "").parse().unwrap());
+            } else {
                 lines.push(last_line);
-                None
+                break;
+            }
         }
-        };
 
         let animation_frames = lines[1..].join("");
-        let animation_frames: Vec<&str> = animation_frames.split("\n>\n").collect();
+        let animation_frames: Vec<&str> = animation_frames.split(">").collect();
         let animation_frames: Vec<Image> = animation_frames.iter().map(|&frame| {
             Image::from(frame.to_string())
         }).collect();
 
-        Tile { id, name, wall, animation_frames }
+        Tile { id, name, wall, animation_frames, colour_id }
     }
 }
 
@@ -55,11 +73,12 @@ impl ToString for Tile {
     #[inline]
     fn to_string(&self) -> String {
         format!(
-            "TIL {}\n{}{}{}",
+            "TIL {}\n{}{}{}{}",
             self.id.to_base36(),
             self.animation_frames.to_string(),
             self.name_line(),
-            if self.wall {"\nWAL true"} else {""}
+            self.wall_line(),
+            self.colour_line(),
         )
     }
 }
@@ -71,12 +90,13 @@ fn test_tile_from_string() {
     let expected = Tile {
         id: 35,
         name: Some("concrete 1".to_string()),
-        wall: true,
+        wall: Some(true),
         animation_frames: vec![
             Image {
                 pixels: vec![1; 64]
             }
         ],
+        colour_id: None
     };
 
     assert_eq!(output, expected);
@@ -87,11 +107,12 @@ fn test_tile_to_string() {
     let output = Tile {
         id: 262,
         name: Some("chequers".to_string()),
-        wall: false,
+        wall: None,
         animation_frames: vec![
             mock::image::chequers_1(),
             mock::image::chequers_2(),
-        ]
+        ],
+        colour_id: None
     }.to_string();
 
     let expected = include_str!("test-resources/tile-chequers").to_string();