fidl_next_bind/future/
send.rs

1// Copyright 2025 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use core::future::Future;
6use core::pin::Pin;
7use core::task::{Context, Poll, ready};
8
9use fidl_next_codec::EncodeError;
10use fidl_next_protocol::Transport;
11use pin_project::pin_project;
12
13use crate::Error;
14
15macro_rules! define_send_future {
16    (
17        $(#[$metas:meta])*
18        $name:ident<$($lifetime:lifetime,)? T: Transport>($future:ty) => $encoded:ident {
19            state = $state:ident,
20            proj = $proj:ident,
21            own = $own:ident,
22        }
23    ) => {
24        #[pin_project(project = $proj, project_replace = $own)]
25        enum $state<$($lifetime,)? T: Transport> {
26            EncodeError(EncodeError),
27            Sending(#[pin] $future),
28            Finished,
29        }
30
31        impl<$($lifetime,)? T: Transport> $state<$($lifetime,)? T> {
32            fn poll_state(
33                mut self: Pin<&mut Self>,
34                cx: &mut Context<'_>,
35            ) -> Poll<Result<(), Error<T::Error>>> {
36                match self.as_mut().project() {
37                    $proj::EncodeError(_) => {
38                        let state = self.project_replace(Self::Finished);
39                        let $own::EncodeError(error) = state else {
40                            unreachable!();
41                        };
42                        Poll::Ready(Err(Error::Encode(error)))
43                    }
44                    $proj::Sending(future) => match ready!(future.poll(cx)) {
45                        Ok(()) => Poll::Ready(Ok(())),
46                        Err(error) => Poll::Ready(Err(Error::Protocol(error))),
47                    },
48                    $proj::Finished => panic!("State polled after completing"),
49                }
50            }
51        }
52
53        $(#[$metas])*
54        #[must_use = "futures do nothing unless polled"]
55        #[pin_project]
56        pub struct $name<
57            $($lifetime,)?
58            T: Transport,
59        > {
60            #[pin]
61            state: $state<$($lifetime,)? T>,
62        }
63
64        impl<$($lifetime,)? T: Transport> $name<$($lifetime,)? T> {
65            #[doc = concat!("Returns a `", stringify!($name), "` wrapping the given result.")]
66            pub fn from_untyped(result: Result<$future, EncodeError>) -> Self {
67                Self {
68                    state: match result {
69                        Err(error) => $state::EncodeError(error),
70                        Ok(future) => $state::Sending(future),
71                    },
72                }
73            }
74
75            /// Encodes the message.
76            ///
77            /// Returns a future which sends the message, or an error if it failed.
78            pub fn encode(self) -> Result<$encoded<$($lifetime,)? T>, Error<T::Error>> {
79                Ok($encoded {
80                    state: match self.state {
81                        $state::EncodeError(error) => return Err(Error::Encode(error)),
82                        state => state,
83                    },
84                })
85            }
86        }
87
88        impl<'a, T: Transport> Future for $name<$($lifetime,)? T> {
89            type Output = Result<(), Error<T::Error>>;
90
91            fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
92                self.project().state.poll_state(cx)
93            }
94        }
95
96        #[doc = concat!("An encoded `", stringify!($name), "`.")]
97        ///
98        /// This future has already been successfully encoded. It still needs to be
99        /// sent.
100        #[must_use = "futures do nothing unless polled"]
101        #[pin_project]
102        pub struct $encoded<
103            $($lifetime,)?
104            T: Transport,
105        > {
106            #[pin]
107            state: $state<$($lifetime,)? T>,
108        }
109
110        impl<$($lifetime,)? T: Transport> Future for $encoded<$($lifetime,)? T> {
111            type Output = Result<(), Error<T::Error>>;
112
113            fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
114                self.project().state.poll_state(cx)
115            }
116        }
117    }
118}
119
120define_send_future! {
121    /// A future which sends an encoded message to a connection.
122    SendFuture<'a, T: Transport>(fidl_next_protocol::SendFuture<'a, T>) => EncodedSendFuture {
123        state = SendFutureState,
124        proj = SendFutureProj,
125        own = SendFutureOwn,
126    }
127}
128
129define_send_future! {
130    /// A future which responds to a request with an encoded message.
131    RespondFuture<T: Transport>(fidl_next_protocol::RespondFuture<T>) => EncodedRespondFuture {
132        state = RespondFutureState,
133        proj = RespondFutureProj,
134        own = RespondFutureOwn,
135    }
136}
fidl_next_bind/future/send.rs

fidl_next_bind/future/
send.rs
