Integrate RMW message methods into ActionImpl

Rather than having a bunch of standalone traits implementing various
message functions like `ExtractUuid` and `SetAccepted`, with the
trait bounds on each associated type in `ActionImpl`, we'll instead add
these functions directly to the `ActionImpl` trait. This is simpler on
both the rosidl_runtime_rs and the rclrs side.

rclrs/src/action/server.rs

@@ -5,7 +5,7 @@ use crate::{
     wait::WaitableNumEntities,
     Clock, DropGuard, NodeHandle, RclrsError, ENTITY_LIFECYCLE_MUTEX,
 };
-use rosidl_runtime_rs::{Action, Message, Service};
+use rosidl_runtime_rs::{Action, ActionImpl, Message, Service};
 use std::{
     ffi::CString,
     sync::{atomic::AtomicBool, Arc, Mutex, MutexGuard},
@@ -165,7 +165,7 @@ where
             writer_guid: [0; 16],
             sequence_number: 0,
         };
-        type RmwRequest<T> = <<<T as rosidl_runtime_rs::ActionImpl>::SendGoalService as Service>::Request as Message>::RmwMsg;
+        type RmwRequest<T> = <<<T as ActionImpl>::SendGoalService as Service>::Request as Message>::RmwMsg;
         let mut request_rmw = RmwRequest::<T>::default();
         let handle = &*self.handle.lock();
         unsafe {
@@ -186,10 +186,9 @@ where
         mut request_id: rmw_request_id_t,
         accepted: bool,
     ) -> Result<(), RclrsError> {
-        type RmwResponse<T> = <<<T as rosidl_runtime_rs::ActionImpl>::SendGoalService as Service>::Response as Message>::RmwMsg;
+        type RmwResponse<T> = <<<T as ActionImpl>::SendGoalService as Service>::Response as Message>::RmwMsg;
         let mut response_rmw = RmwResponse::<T>::default();
-        // TODO(nwn): Set the `accepted` field through a trait, similarly to how we extracted the UUID.
-        // response_rmw.accepted = accepted;
+        <T as ActionImpl>::set_goal_response_accepted(&mut response_rmw, accepted);
         let handle = &*self.handle.lock();
         let result = unsafe {
             // SAFETY: The action server handle is locked and so synchronized with other
@@ -232,8 +231,7 @@ where
             Err(err) => return Err(err),
         };
 
-        let mut uuid = GoalUuid::default();
-        rosidl_runtime_rs::ExtractUuid::extract_uuid(&request, &mut uuid.0);
+        let uuid = GoalUuid(<T as ActionImpl>::get_goal_request_uuid(&request));
 
         let response: GoalResponse = {
             todo!("Optionally convert request to an idiomatic type for the user's callback.");

rosidl_runtime_rs/src/lib.rs

@@ -9,4 +9,4 @@ mod string;
 pub use string::{BoundedString, BoundedWString, String, StringExceedsBoundsError, WString};
 
 mod traits;
-pub use traits::{Action, ActionImpl, ExtractUuid, Message, RmwMessage, SequenceAlloc, Service};
+pub use traits::{Action, ActionImpl, Message, RmwMessage, SequenceAlloc, Service};

rosidl_runtime_rs/src/traits.rs

@@ -188,19 +188,17 @@ pub trait ActionImpl: 'static {
     type FeedbackMessage: Message;
 
     /// The send_goal service associated with this action.
-    type SendGoalService: Service<Request: Message<RmwMsg: ExtractUuid>>;
+    type SendGoalService: Service;
 
     /// The cancel_goal service associated with this action.
     type CancelGoalService: Service;
 
     /// The get_result service associated with this action.
     type GetResultService: Service;
-}
 
-/// Trait for types containing a special UUID field.
-///
-/// User code never needs to implement this trait, nor call its method.
-pub trait ExtractUuid: 'static {
-    /// Copies the UUID field from `self` into the provided buffer.
-    fn extract_uuid(&self, bytes: &mut [u8; 16]);
+    /// Get the UUID of a goal request.
+    fn get_goal_request_uuid(request: &<<Self::SendGoalService as Service>::Request as Message>::RmwMsg) -> [u8; 16];
+
+    /// Sets the `accepted` field of a goal response.
+    fn set_goal_response_accepted(response: &mut <<Self::SendGoalService as Service>::Response as Message>::RmwMsg, accepted: bool);
 }