feat(comms): add or_optional trait extension for RpcStatus

comms/core/src/lib.rs

@@ -55,6 +55,7 @@ pub mod utils;
 // TODO: Test utils should be part of a `tari_comms_test` crate
 // #[cfg(test)]
 pub mod test_utils;
+pub mod traits;
 
 //---------------------------------- Re-exports --------------------------------------------//
 // Rather than requiring dependent crates to import dependencies for use with `tari_comms` we re-export them here.

comms/core/src/protocol/rpc/status.rs

@@ -26,11 +26,11 @@ use log::*;
 use thiserror::Error;
 
 use super::RpcError;
-use crate::proto;
+use crate::{proto, traits::OrOptional};
 
 const LOG_TARGET: &str = "comms::rpc::status";
 
-#[derive(Debug, Error, Clone)]
+#[derive(Debug, Error, Clone, PartialEq, Eq)]
 pub struct RpcStatus {
     code: RpcStatusCode,
     details: String,
@@ -141,6 +141,10 @@ impl RpcStatus {
     pub fn is_ok(&self) -> bool {
         self.code.is_ok()
     }
+
+    pub fn is_not_found(&self) -> bool {
+        self.code.is_not_found()
+    }
 }
 
 impl Display for RpcStatus {
@@ -202,6 +206,15 @@ impl<T, E: std::error::Error> RpcStatusResultExt<T> for Result<T, E> {
     }
 }
 
+impl<T> OrOptional<T> for Result<T, RpcStatus> {
+    type Error = RpcStatus;
+
+    fn or_optional(self) -> Result<Option<T>, Self::Error> {
+        self.map(Some)
+            .or_else(|status| if status.is_not_found() { Ok(None) } else { Err(status) })
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum RpcStatusCode {
     /// Request succeeded
@@ -296,4 +309,17 @@ mod test {
         assert_eq!(RpcStatusCode::from(Conflict as u32), Conflict);
         assert_eq!(RpcStatusCode::from(123), InvalidRpcStatusCode);
     }
+
+    #[test]
+    fn rpc_status_or_optional() {
+        assert!(Result::<(), RpcStatus>::Ok(()).or_optional().is_ok());
+        assert_eq!(
+            Result::<(), _>::Err(RpcStatus::not_found("foo")).or_optional(),
+            Ok(None)
+        );
+        assert_eq!(
+            Result::<(), _>::Err(RpcStatus::general("foo")).or_optional(),
+            Err(RpcStatus::general("foo"))
+        );
+    }
 }

comms/core/src/traits.rs

@@ -0,0 +1,28 @@
+//  Copyright 2022, The Tari Project
+//
+//  Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
+//  following conditions are met:
+//
+//  1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
+//  disclaimer.
+//
+//  2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
+//  following disclaimer in the documentation and/or other materials provided with the distribution.
+//
+//  3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote
+//  products derived from this software without specific prior written permission.
+//
+//  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+//  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+//  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+//  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+//  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+//  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+//  USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/// Extension trait that typically converts Result<T, Self::Error> to Result<Option<T>, Self::Error>
+/// based on some implementer logic.
+pub trait OrOptional<T> {
+    type Error;
+    fn or_optional(self) -> Result<Option<T>, Self::Error>;
+}