Make extended route types survive a parsing / serializing round trip

src/enums.rs

@@ -86,7 +86,7 @@ impl Serialize for LocationType {
 
 /// Describes the kind of [Route]. See <https://gtfs.org/reference/static/#routestxt> `route_type`
 ///
-/// -ome route types are extended GTFS (<https://developers.google.com/transit/gtfs/reference/extended-route-types)>
+/// Some route types are extended GTFS (<https://developers.google.com/transit/gtfs/reference/extended-route-types)>
 #[derive(Debug, Default, Copy, Clone, PartialEq, Eq, Hash)]
 pub enum RouteType {
     /// Tram, Streetcar, Light rail. Any light rail or street level system within a metropolitan area
@@ -116,26 +116,52 @@ pub enum RouteType {
     Other(i16),
 }
 
+impl RouteType {
+    /// Simplify [`RouteType::Other`] into the named variants of the enum.
+    /// This may lose precision for extended route types.
+    pub fn simplify(&self) -> RouteType {
+        match self {
+            RouteType::Other(extended) => {
+                let hundreds = extended / 100;
+                match (*extended, hundreds) {
+                    (0, _) | (_, 9) => RouteType::Tramway,
+                    (1, _) | (_, 4) => RouteType::Subway,
+                    (2, _) | (_, 1) => RouteType::Rail,
+                    (3, _) | (_, 7) | (_, 8) => RouteType::Bus,
+                    (4, _) | (_, 10) | (_, 12) => RouteType::Ferry,
+                    (5, _) => RouteType::CableCar,
+                    (6, _) | (_, 13) => RouteType::Gondola,
+                    (7, _) | (_, 14) => RouteType::Funicular,
+                    (_, 2) => RouteType::Coach,
+                    (_, 11) => RouteType::Air,
+                    (_, 15) => RouteType::Taxi,
+                    _ => RouteType::Other(*extended),
+                }
+            }
+            route_type => *route_type,
+        }
+    }
+}
+
 impl<'de> Deserialize<'de> for RouteType {
     fn deserialize<D>(deserializer: D) -> Result<RouteType, D::Error>
     where
         D: Deserializer<'de>,
     {
         let i = i16::deserialize(deserializer)?;
 
-        let hundreds = i / 100;
-        Ok(match (i, hundreds) {
-            (0, _) | (_, 9) => RouteType::Tramway,
-            (1, _) | (_, 4) => RouteType::Subway,
-            (2, _) | (_, 1) => RouteType::Rail,
-            (3, _) | (_, 7) | (_, 8) => RouteType::Bus,
-            (4, _) | (_, 10) | (_, 12) => RouteType::Ferry,
-            (5, _) => RouteType::CableCar,
-            (6, _) | (_, 13) => RouteType::Gondola,
-            (7, _) | (_, 14) => RouteType::Funicular,
-            (_, 2) => RouteType::Coach,
-            (_, 11) => RouteType::Air,
-            (_, 15) => RouteType::Taxi,
+        Ok(match i {
+            0 => RouteType::Tramway,
+            1 => RouteType::Subway,
+            2 => RouteType::Rail,
+            3 => RouteType::Bus,
+            4 => RouteType::Ferry,
+            5 => RouteType::CableCar,
+            6 => RouteType::Gondola,
+            7 => RouteType::Funicular,
+            200 => RouteType::Coach,
+            1100 => RouteType::Air,
+            1500 => RouteType::Taxi,
             _ => RouteType::Other(i),
         })
     }