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#![deny(warnings)]
#![deny(missing_docs)]
#![deny(unused_must_use)]
use futures::future::BoxFuture;
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct MustFuture<F: std::future::Future> {
sub_fut: F,
}
impl<F: std::future::Future> MustFuture<F> {
pin_utils::unsafe_pinned!(sub_fut: F);
}
impl<F: std::future::Future> From<F> for MustFuture<F> {
fn from(f: F) -> Self {
Self { sub_fut: f }
}
}
impl<F: std::future::Future> std::future::Future for MustFuture<F> {
type Output = F::Output;
fn poll(
self: std::pin::Pin<&mut Self>,
cx: &mut std::task::Context,
) -> std::task::Poll<Self::Output> {
let p: std::pin::Pin<&mut F> = self.sub_fut();
std::future::Future::poll(p, cx)
}
}
impl<F: std::future::Future + std::marker::Unpin> std::marker::Unpin for MustFuture<F> {}
impl<F: std::future::Future> std::fmt::Debug for MustFuture<F> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("MustFuture").finish()
}
}
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct MustBoxFuture<'lt, T> {
sub_fut: BoxFuture<'lt, T>,
}
impl<'lt, T> MustBoxFuture<'lt, T> {
pub fn new<F: 'lt + std::future::Future<Output = T> + Send>(f: F) -> Self {
Self {
sub_fut: futures::future::FutureExt::boxed(f),
}
}
}
impl<T: ?Sized> IntoMustBoxFuture for T where T: std::future::Future {}
pub trait IntoMustBoxFuture: std::future::Future {
fn must_box<'a>(self) -> MustBoxFuture<'a, Self::Output>
where
Self: 'a + Sized + Send,
{
MustBoxFuture::new(self)
}
}
impl<'lt, T> From<BoxFuture<'lt, T>> for MustBoxFuture<'lt, T> {
fn from(f: BoxFuture<'lt, T>) -> Self {
Self { sub_fut: f }
}
}
impl<'lt, T> std::future::Future for MustBoxFuture<'lt, T> {
type Output = T;
fn poll(
mut self: std::pin::Pin<&mut Self>,
cx: &mut std::task::Context,
) -> std::task::Poll<Self::Output> {
std::future::Future::poll(self.sub_fut.as_mut(), cx)
}
}
impl<'lt, T> std::fmt::Debug for MustBoxFuture<'lt, T> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("MustBoxFuture").finish()
}
}
#[cfg(test)]
mod tests {
use super::*;
use futures::future::FutureExt;
#[tokio::test]
pub async fn must_box_future_is_debug() {
fn get_future() -> MustBoxFuture<'static, &'static str> {
async { "test1" }.boxed().into()
}
assert_eq!("MustBoxFuture", &format!("{:?}", get_future()));
}
#[tokio::test]
pub async fn must_box_future_can_still_process() {
fn get_future() -> MustBoxFuture<'static, &'static str> {
async { "test1" }.boxed().into()
}
assert_eq!("test1", get_future().await);
}
#[tokio::test]
pub async fn must_box_future_with_new() {
fn get_future() -> MustBoxFuture<'static, &'static str> {
MustBoxFuture::new(async { "test1" })
}
assert_eq!("test1", get_future().await);
}
#[tokio::test]
pub async fn must_box_future_with_must_box() {
fn get_future() -> MustBoxFuture<'static, &'static str> {
async { "test1" }.must_box()
}
assert_eq!("test1", get_future().await);
}
#[tokio::test]
pub async fn must_future_is_debug() {
fn get_future() -> MustFuture<BoxFuture<'static, &'static str>> {
async { "test2" }.boxed().into()
}
assert_eq!("MustFuture", &format!("{:?}", get_future()));
}
#[tokio::test]
pub async fn must_future_can_still_process() {
fn get_future() -> MustFuture<BoxFuture<'static, &'static str>> {
async { "test2" }.boxed().into()
}
assert_eq!("test2", get_future().await);
}
}