improved NexusID parsing

src/types/nexus_id.rs

@@ -1,6 +1,7 @@
-use serde::{Deserialize, Serialize};
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+use std::str::FromStr;
 
-#[derive(Debug, Deserialize, Serialize, Clone, Copy)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct NexusID {
     mod_id: u64,
     file_id: u64,
@@ -11,3 +12,59 @@ impl NexusID {
         Self { mod_id, file_id }
     }
 }
+
+impl Serialize for NexusID {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let s = format!("{}:{}", self.mod_id, self.file_id);
+        serializer.serialize_str(&s)
+    }
+}
+
+impl<'de> Deserialize<'de> for NexusID {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let s = String::deserialize(deserializer)?;
+        let mut parts = s.split(':');
+
+        let mod_id = parts
+            .next()
+            .ok_or_else(|| serde::de::Error::custom("missing first value"))
+            .and_then(|p| u64::from_str(p).map_err(serde::de::Error::custom))?;
+
+        let file_id = parts
+            .next()
+            .ok_or_else(|| serde::de::Error::custom("missing second value"))
+            .and_then(|p| u64::from_str(p).map_err(serde::de::Error::custom))?;
+
+        if parts.next().is_some() {
+            return Err(serde::de::Error::custom("too many parts"));
+        }
+
+        Ok(Self { mod_id, file_id })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[derive(Deserialize, Serialize, PartialEq, Debug)]
+    struct Wrapper {
+        value: NexusID,
+    }
+
+    #[test]
+    fn serde_roundtrip() {
+        let val = Wrapper {
+            value: NexusID::new(1234, 5678),
+        };
+        let serialized = toml::to_string(&val).unwrap();
+        let deserialized: Wrapper = toml::from_str(&serialized).unwrap();
+        assert_eq!(val, deserialized);
+    }
+}