52 lines
1.3 KiB
Rust
52 lines
1.3 KiB
Rust
use futures::prelude::*;
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use futures_timer::Delay;
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use std::{
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pin::Pin,
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task::{Context, Poll},
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time::Duration,
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};
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#[derive(Copy, Clone)]
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enum MetronomeState {
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Snooze,
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SetAlarm,
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}
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pub struct Metronome {
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delay: Delay,
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period: Duration,
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state: MetronomeState,
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}
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impl Metronome {
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/// Create a new metronome source with a defined cycle duration.
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pub fn new(cycle: Duration) -> Self {
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let period = cycle.into();
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Self { period, delay: Delay::new(period), state: MetronomeState::Snooze }
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}
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}
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impl futures::Stream for Metronome {
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type Item = ();
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fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
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loop {
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match self.state {
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MetronomeState::SetAlarm => {
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let val = self.period;
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self.delay.reset(val);
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self.state = MetronomeState::Snooze;
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},
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MetronomeState::Snooze => {
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if !Pin::new(&mut self.delay).poll(cx).is_ready() {
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break
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}
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self.state = MetronomeState::SetAlarm;
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return Poll::Ready(Some(()))
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},
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}
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}
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Poll::Pending
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}
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}
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