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use super::{context::set_task_context, Context, Effectful, Event, Poll};
use std::ops::{Generator, GeneratorState};
use std::pin::Pin;
use pin_project::pin_project;
#[pin_project]
struct GenEffectful<G>(#[pin] G);
pub fn from_generator<G, Output, Effect>(x: G) -> impl Effectful<Output = Output, Effect = Effect>
where
G: Generator<Return = Output, Yield = Poll<!, Effect>>,
{
GenEffectful(x)
}
impl<G, Output, Effect> Effectful for GenEffectful<G>
where
G: Generator<Return = Output, Yield = Poll<!, Effect>>,
{
type Output = Output;
type Effect = Effect;
#[inline]
fn poll(self: Pin<&mut Self>, cx: &Context) -> Poll<Self::Output, Self::Effect> {
set_task_context(cx, || match self.project().0.resume() {
GeneratorState::Complete(v) => Poll::complete(v),
GeneratorState::Yielded(Poll::Event(Event::Effect(e))) => Poll::effect(e),
GeneratorState::Yielded(Poll::Pending) => Poll::Pending,
GeneratorState::Yielded(Poll::Event(Event::Complete(never))) => never,
})
}
}