function for optional lines of game data

src/lib.rs

@@ -30,6 +30,7 @@ use room::Room;
 use sprite::Sprite;
 use tile::Tile;
 use variable::Variable;
+use std::fmt::Display;
 
 #[derive(Debug, Eq, PartialEq)]
 pub struct Instance {
@@ -95,3 +96,18 @@ impl ToBase36 for u64 {
 fn test_to_base36() {
     assert_eq!((37 as u64).to_base36(), "11");
 }
+
+/// e.g. `\nNAME DLG_0`
+fn optional_data_line<T: Display>(label: &str, item: Option<T>) -> String {
+    if item.is_some() {
+        format!("\n{} {}", label, item.unwrap())
+    } else {
+        "".to_string()
+    }
+}
+
+#[test]
+fn test_optional_data_line() {
+    let output = optional_data_line("NAME", mock::item().name);
+    assert_eq!(output, "\nNAME door".to_string());
+}

src/sprite.rs

@@ -1,4 +1,4 @@
-use crate::{AnimationFrames, Image, Position, mock, from_base36, ToBase36};
+use crate::{AnimationFrames, Image, Position, mock, from_base36, ToBase36, optional_data_line};
 
 #[derive(Debug, Eq, PartialEq)]
 pub struct Sprite {
@@ -10,6 +10,16 @@ pub struct Sprite {
     pub position: Position,
 }
 
+impl Sprite {
+    fn name_line(&self) -> String {
+        optional_data_line("NAME", self.name.as_ref())
+    }
+
+    fn dialogue_line(&self) -> String {
+        optional_data_line("DLG", self.dialogue_id.as_ref())
+    }
+}
+
 impl From<String> for Sprite {
     fn from(string: String) -> Sprite {
         let mut lines: Vec<&str> = string.lines().collect();
@@ -59,8 +69,8 @@ impl ToString for Sprite {
             "SPR {}\n{}{}{}\nPOS {} {}",
             self.id.to_base36(),
             self.animation_frames.to_string(),
-            if self.name.as_ref().is_some() { format!("\nNAME {}", self.name.as_ref().unwrap()) } else { "".to_string() },
+            self.name_line(),
-            if self.dialogue_id.as_ref().is_some() { format!("\nDLG {}", self.dialogue_id.as_ref().unwrap()) } else { "".to_string() },
+            self.dialogue_line(),
             self.room_id.to_base36(),
             self.position.to_string(),
         )