Implement Decodable for OsType

src/cache.rs

@@ -105,7 +105,7 @@ impl Cache {
         let platform = match self.os {
             OsType::Linux => Some("linux"),
             OsType::OsX => Some("osx"),
-            OsType::SunOS => None, // TODO: Does Rust support SunOS
+            OsType::SunOs => None, // TODO: Does Rust support SunOS?
             OsType::Other => None,
         };
 

src/main.rs

@@ -73,7 +73,7 @@ struct Args {
     flag_version: bool,
     flag_list: bool,
     flag_render: Option<String>,
-    flag_os: Option<String>,  // TODO enum
+    flag_os: Option<OsType>,
     flag_update: bool,
     flag_clear_cache: bool,
 }
@@ -173,11 +173,6 @@ fn main() {
         process::exit(1);
     }
 
-    // Override OS and exit
-    if let Some(os) = args.flag_os {
-        println!("Flag --os not yet implemented.");
-    }
-
     // Show command from cache
     if let Some(command) = args.arg_command {
 

src/types.rs

@@ -1,15 +1,38 @@
 //! Types used in the client.
 
+use rustc_serialize::{Decodable, Decoder};
+
+
 #[derive(Debug, Eq, PartialEq)]
 #[allow(dead_code)]
 pub enum OsType {
     Linux,
     OsX,
-    SunOS,
+    SunOs,
     Other,
 }
 
 
+/// Custom Decodable implementation, so that we can parse command line arguments
+/// directly into an `OsType` instance.
+impl Decodable for OsType {
+    fn decode<D: Decoder>(d: &mut D) -> Result<Self, D::Error> {
+        return d.read_str().and_then(|input| {
+            let lowercase = input.to_lowercase();
+            match &lowercase[..] {
+                "linux" => Ok(OsType::Linux),
+                "osx" => Ok(OsType::OsX),
+                "sunos" => Ok(OsType::SunOs),
+                "other" => Ok(OsType::Other),
+                _ => Err(d.error(&format!("Invalid OS type: '{}'. Choose one of 'linux', \
+                                           'osx', 'sunos' or 'other'.", lowercase)))
+            }
+        });
+    }
+}
+
+
+
 #[derive(Debug, Eq, PartialEq)]
 pub enum LineType {
     Empty,
@@ -35,3 +58,30 @@ impl<'a> From<&'a str> for LineType {
         }
     }
 }
+
+#[cfg(test)]
+mod test {
+    extern crate rustc_serialize;
+    extern crate docopt;
+
+    use super::OsType::{self, Linux, OsX, SunOs, Other};
+    use rustc_serialize::json;
+
+    #[test]
+    fn test_os_type_decoding_regular() {
+        assert_eq!(json::decode::<OsType>("\"linux\"").unwrap(), Linux);
+        assert_eq!(json::decode::<OsType>("\"osx\"").unwrap(), OsX);
+        assert_eq!(json::decode::<OsType>("\"sunos\"").unwrap(), SunOs);
+        assert_eq!(json::decode::<OsType>("\"other\"").unwrap(), Other);
+    }
+
+    #[test]
+    fn test_os_type_decoding_uppercase() {
+        assert_eq!(json::decode::<OsType>("\"Linux\"").unwrap(), Linux);
+        assert_eq!(json::decode::<OsType>("\"LINUX\"").unwrap(), Linux);
+    }
+#[test]
+    fn test_os_type_decoding_unknown() {
+        assert!(json::decode::<OsType>("\"lindows\"").is_err());
+    }
+}