clean up get_mpv_property_string()

src/ipc.rs

@@ -189,10 +189,21 @@ pub fn get_mpv_property<T: TypeHandler>(instance: &Mpv, property: &str) -> Resul
 
 pub fn get_mpv_property_string(instance: &Mpv, property: &str) -> Result<String, Error> {
     let ipc_string = format!("{{ \"command\": [\"get_property\",\"{}\"] }}\n", property);
-    match serde_json::from_str::<Value>(&send_command_sync(instance, &ipc_string)) {
+    let val = serde_json::from_str::<Value>(&send_command_sync(instance, &ipc_string))
-        Ok(val) => {
+        .map_err(|why| Error(ErrorCode::JsonParseError(why.to_string())))?;
-            if let Value::Object(map) = val {
+
-                if let Value::String(ref error) = map["error"] {
+    let map = if let Value::Object(map) = val {
+        Ok(map)
+    } else {
+        Err(Error(ErrorCode::UnexpectedValue))
+    }?;
+
+    let error = if let Value::String(ref error) = map["error"] {
+        Ok(error)
+    } else {
+        Err(Error(ErrorCode::UnexpectedValue))
+    }?;
+
     if error == "success" && map.contains_key("data") {
         match map["data"] {
             Value::Bool(b) => Ok(b.to_string()),
@@ -203,17 +214,11 @@ pub fn get_mpv_property_string(instance: &Mpv, property: &str) -> Result<String,
             _ => Err(Error(ErrorCode::UnsupportedType)),
         }
     } else {
+        // TODO: there is a bug here
+        // this could return MpvError("success") if error == "success" but the map doesn't contain
+        // data
         Err(Error(ErrorCode::MpvError(error.to_string())))
     }
-                } else {
-                    Err(Error(ErrorCode::UnexpectedValue))
-                }
-            } else {
-                Err(Error(ErrorCode::UnexpectedValue))
-            }
-        }
-        Err(why) => Err(Error(ErrorCode::JsonParseError(why.to_string()))),
-    }
 }
 
 pub fn set_mpv_property<T: TypeHandler>(