WIP: workaround for infinite instruments split

examples/hsom-exercises/main.rs

@@ -6,7 +6,7 @@ use std::path::PathBuf;
 use clap::{Args, Parser, Subcommand};
 use ux2::u7;
 
-use musik::{p, AbsPitch, Dur, Interval, Music, Performable as _, Performance, Pitch, Volume};
+use musik::{p, AbsPitch, Dur, Interval, Music, Performable as _, Pitch, Volume};
 
 mod ch1;
 mod ch2;
@@ -97,10 +97,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     let perf = m.perform();
     if cli.mode.play {
-        // TODO: make the whole flow lazy (test on `ch6 shepard-desc`):
-        //  - introduce lazy `midly::Smf`, then check that it starts real sound almost instantly without any `take`;
-        let perf = Performance::with_events(perf.iter().take(10_000));
-        perf.play()?;
+        perf.clone().play()?;
     }
 
     if let Some(path) = cli.mode.save_into {

src/output/midi/convert.rs

@@ -86,6 +86,9 @@ impl Performance {
         (stream, Timing::Metrical(DEFAULT_TIME_DIV))
     }
 
+    // after one hour stop trying to find new instruments in the Performance
+    const FIND_NEW_INSTRUMENTS_IN: Option<Duration> = Some(Duration::from_secs(3_600));
+
     fn split_by_instruments(self) -> impl Iterator<Item = (InstrumentName, Self)> {
         let mut stream = {
             let x: LazyList<_> = self.into_iter();
@@ -98,7 +101,12 @@ impl Performance {
             let instrument = head.instrument.clone();
             let i = instrument.clone();
 
-            let (this_instrument, other) = partition(current_stream, move |e| e.instrument == i);
+            let trying_fn = Self::FIND_NEW_INSTRUMENTS_IN.map(|max_dur| {
+                move |ev: &Event| u64::from(ev.start_time.to_integer()) < max_dur.as_secs()
+            });
+
+            let (this_instrument, other) =
+                partition(current_stream, move |e| e.instrument == i, trying_fn);
             stream = Some(LazyList(Box::new(other)).peekable());
             Some((instrument, Self::with_events(this_instrument)))
         })

src/utils/iter.rs

@@ -201,19 +201,23 @@ where
     }
 }
 
-pub fn partition<I, T, F>(
+pub fn partition<I, T, F, TakeF>(
     iter: I,
     predicate: F,
+    take_only: Option<TakeF>,
 ) -> (
     impl CloneableIterator<Item = T>,
     impl CloneableIterator<Item = T>,
 )
 where
     I: Iterator<Item = T> + Clone,
     F: Fn(&T) -> bool + Clone + 'static,
+    TakeF: Fn(&T) -> bool + Clone + 'static,
 {
-    let f = predicate.clone();
-    let left = iter.clone().filter(move |x| f(x));
-    let right = iter.filter(move |x| !predicate(x));
+    let take = move |x: &T| take_only.as_ref().map_or(true, |take_only| take_only(x));
+    let filter = move |x: &T| predicate(x);
+
+    let left = iter.clone().take_while(take.clone()).filter(filter.clone());
+    let right = iter.take_while(take).filter(move |x| !filter(x));
     (left, right)
 }