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use std::collections::VecDeque;
use std::time::{Duration, Instant};
use crate::error::{Error, Result};
use crate::types::{
CatchClass, CatchEvent, CatchFilter, Class, Direction, Input, InputEvent, Usage,
};
use super::Device;
use super::catch::EventStream;
fn class_index(class: Class) -> usize {
match class {
Class::Button => 0,
Class::Key => 1,
Class::Media => 2,
}
}
/// A live stream of decoded [`InputEvent`]s: press and release edges, and motion.
///
/// Built on the same subscription as [`EventStream`], with the held-usage snapshots turned into the
/// edges they represent. One report can produce several events, so `recv` takes `&mut self`.
#[derive(Debug)]
pub struct InputStream {
events: EventStream,
filters: Vec<CatchFilter>,
held: [Vec<Usage>; 3],
pending: VecDeque<InputEvent>,
}
impl InputStream {
fn new(events: EventStream, filters: Vec<CatchFilter>) -> InputStream {
InputStream {
events,
filters,
held: [Vec::new(), Vec::new(), Vec::new()],
pending: VecDeque::new(),
}
}
// A snapshot is the CLASS's state, so the box sends every held usage of that class once ANY
// subscriber in the process has widened the table -- routing has to be class-only or the release
// edge is lost. That is right for delivery and wrong for decoding: a stream that asked for one
// key would otherwise report edges for every key someone else subscribed to. Filter here instead,
// where the subscriber's own address is still known.
//
// The class check is not redundant: each usage carries its own class byte, and one that disagrees
// with the frame's would otherwise be filed under the wrong class and could never be released.
fn subscribed(&self, class: Class, usage: Usage) -> bool {
usage.class == class
&& self
.filters
.iter()
.any(|f| f.matches(CatchClass::from(class), usage.id, Direction::Both))
}
fn pump(&mut self, event: CatchEvent) {
match event {
// A report that moved nothing is not motion. The box never emits one, but the routing
// fallback for an unaddressable event delivers it, and a phantom zero-delta event is the
// exact shape the emission-suppression work was about.
CatchEvent::Motion(m) if m.axes().next().is_some() => {
self.pending.push_back(InputEvent {
ts_us: m.ts_us,
clock: m.clock,
input: Input::Motion {
dx: m.dx,
dy: m.dy,
dz: m.dz,
},
})
}
CatchEvent::Motion(_) => {}
CatchEvent::Usages(u) => {
let slot = class_index(u.class);
// Deduplicated: a malformed snapshot listing one usage twice would otherwise fire two
// presses with no release between them, and leave `held` a multiset.
let mut now: Vec<Usage> = Vec::with_capacity(u.usages.len());
for usage in u.usages {
if self.subscribed(u.class, usage) && !now.contains(&usage) {
now.push(usage);
}
}
let was = std::mem::take(&mut self.held[slot]);
let mut edge = |input| {
self.pending.push_back(InputEvent {
ts_us: u.ts_us,
clock: u.clock,
input,
})
};
// Releases first: within one report a swap reads as "A came up, B went down".
for old in was.iter().filter(|o| !now.contains(o)) {
edge(Input::Release(*old));
}
for fresh in now.iter().filter(|n| !was.contains(n)) {
edge(Input::Press(*fresh));
}
self.held[slot] = now;
}
CatchEvent::Traffic(_) => {}
}
}
/// Block until the next input event.
pub fn recv(&mut self) -> Result<InputEvent> {
loop {
if let Some(e) = self.pending.pop_front() {
return Ok(e);
}
let event = self.events.recv()?;
self.pump(event);
}
}
/// The next decoded event, or `None` if nothing is queued (never blocks).
pub fn try_recv(&mut self) -> Option<InputEvent> {
loop {
if let Some(e) = self.pending.pop_front() {
return Some(e);
}
let event = self.events.try_recv()?;
self.pump(event);
}
}
/// Block up to `timeout` for the next input event.
///
/// `None` means "nothing yet" **or** "nothing ever again", and on a closed stream it returns at
/// once, so a poll loop that ignores [`Self::is_connected`] spins.
pub fn recv_timeout(&mut self, timeout: Duration) -> Option<InputEvent> {
// A timeout too large to add to `now` is a caller asking to wait indefinitely, not one asking
// to give up immediately -- which is what `?` on the overflow would have done.
let Some(deadline) = Instant::now().checked_add(timeout) else {
return self.recv().ok();
};
loop {
if let Some(e) = self.pending.pop_front() {
return Some(e);
}
// A report can decode to nothing at all -- an empty snapshot for a class that was already
// empty -- so the deadline has to survive a pump that yields no event.
let left = deadline.checked_duration_since(Instant::now())?;
let event = self.events.recv_timeout(left)?;
self.pump(event);
}
}
/// Await the next input event; runtime-agnostic, runs under any executor.
#[cfg(feature = "async")]
pub async fn recv_async(&mut self) -> Result<InputEvent> {
loop {
if let Some(e) = self.pending.pop_front() {
return Ok(e);
}
let event = self.events.recv_async().await?;
self.pump(event);
}
}
/// Events the underlying subscription dropped because the consumer fell behind.
pub fn dropped(&self) -> u64 {
self.events.dropped()
}
/// Whether the box is still delivering to this stream. [`Self::recv_timeout`] and
/// [`Self::try_recv`] answer `None` for both "nothing yet" and "nothing ever again"; this
/// separates them.
pub fn is_connected(&self) -> bool {
!self.pending.is_empty() || self.events.is_connected()
}
/// Which usages of `class` are currently held, as this stream has tracked them.
pub fn held(&self, class: Class) -> &[Usage] {
&self.held[class_index(class)]
}
}
impl Iterator for InputStream {
type Item = InputEvent;
fn next(&mut self) -> Option<InputEvent> {
self.recv().ok()
}
}
impl Device {
/// Subscribe to decoded input: press and release edges, and motion.
///
/// ```no_run
/// # use medius::{CatchFilter, Device, Input, Key};
/// # fn f(dev: &Device) -> medius::Result<()> {
/// for ev in dev.input_events([CatchFilter::watch(Key::F)])? {
/// match ev.input {
/// Input::Press(u) => println!("down {u:?}"),
/// Input::Release(u) => println!("up {u:?}"),
/// _ => {}
/// }
/// }
/// # Ok(()) }
/// ```
///
/// # Errors
///
/// Every filter must name an input class and cover both edges. A traffic class gives
/// [`Error::NotAnInputFilter`], [`CatchFilter::everything`] gives [`Error::WildcardNotInput`]
/// (use [`CatchFilter::all_input`]), and a filter narrowed to one edge gives
/// [`Error::HalfEdgeInputFilter`]. The missing edge is what tells a fresh press from a chord, so
/// match on [`Input::Press`] instead.
pub fn input_events(
&self,
filters: impl IntoIterator<Item = CatchFilter>,
) -> Result<InputStream> {
let wanted: Vec<CatchFilter> = filters.into_iter().collect();
for f in &wanted {
match f.class() {
None => return Err(Error::WildcardNotInput),
Some(c) if c.is_traffic() => return Err(Error::NotAnInputFilter { class: c }),
Some(_) if f.direction() != Direction::Both => {
return Err(Error::HalfEdgeInputFilter);
}
Some(_) => {}
}
}
Ok(InputStream::new(self.catch_events(wanted.clone())?, wanted))
}
}