Add custom de-/serializers to Version

in order to serialize it to string.

Author: Matthias Wahl

src/version.rs

@@ -1,3 +1,4 @@
+use serde::{de::Error, de::Visitor, Deserialize, Deserializer, Serialize, Serializer};
 /// The version of the HTTP protocol in use.
 #[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
 #[non_exhaustive]
@@ -18,6 +19,55 @@ pub enum Version {
     Http3_0,
 }
 
+impl Serialize for Version {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&self.to_string())
+    }
+}
+
+struct VersionVisitor;
+
+impl<'de> Visitor<'de> for VersionVisitor {
+    type Value = Version;
+
+    fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(formatter, "a HTTP version as &str")
+    }
+
+    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
+    where
+        E: Error,
+    {
+        match v {
+            "HTTP/0.9" => Ok(Version::Http0_9),
+            "HTTP/1.0" => Ok(Version::Http1_0),
+            "HTTP/1.1" => Ok(Version::Http1_1),
+            "HTTP/2" => Ok(Version::Http2_0),
+            "HTTP/3" => Ok(Version::Http3_0),
+            _ => Err(Error::invalid_value(serde::de::Unexpected::Str(v), &self)),
+        }
+    }
+
+    fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
+    where
+        E: Error,
+    {
+        self.visit_str(&v)
+    }
+}
+
+impl<'de> Deserialize<'de> for Version {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_str(VersionVisitor)
+    }
+}
+
 impl std::fmt::Display for Version {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.write_str(match self {
@@ -54,4 +104,11 @@ mod test {
         assert!(Http1_1 > Http1_0);
         assert!(Http1_0 > Http0_9);
     }
+
+    #[test]
+    fn serde() -> Result<(), serde_json::Error> {
+        assert_eq!("\"HTTP/3\"", serde_json::to_string(&Version::Http3_0)?);
+        assert_eq!(Version::Http1_1, serde_json::from_str("\"HTTP/1.1\"")?);
+        Ok(())
+    }
 }