WIP flattening to midi events

Cargo.lock

@@ -2,12 +2,125 @@
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@@ -24,9 +137,99 @@ dependencies = [
  "minimal-lexical",
 ]
 
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 dependencies = [
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+ "midly",
  "nom",
 ]
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Cargo.toml

@@ -11,3 +11,5 @@ path = "src/bin/main.rs"
 
 [dependencies]
 nom = "*"
+midly = "0.5.3"
+derive_more = "*"

src/bin/main.rs

@@ -1,4 +1,5 @@
 use poly::dsl;
+use poly::midi;
 
 fn main() {
     println!("Hello, world!");

src/dsl/dsl.rs

@@ -6,7 +6,7 @@ use nom::multi::many1;
 use nom::sequence::{separated_pair, tuple, delimited};
 use nom::{Err, IResult};
 use nom::branch::alt;
-use nom::bytes::complete::tag;
+
 use nom::combinator::{map, map_res};
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -40,7 +40,7 @@ pub enum Note {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Times(u16);
+pub struct Times(pub u16);
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum GroupOrNote {
@@ -82,6 +82,7 @@ static ONCE : Times = Times(1);
 static TWICE: Times = Times(2);
 static THRICE : Times = Times(3);
 
+
 fn hit(input: &str) -> IResult<&str, Note> {
     map(char('x'), |_| { Note::Hit })(input)
 }

src/dsl/mod.rs

@@ -1 +1,2 @@
 pub mod dsl;
+pub mod process;

src/dsl/process.rs

@@ -0,0 +1,6 @@
+use super::dsl::{BasicLength};
+
+pub struct TimeSignature {
+    numerator: u8,
+    denominator: BasicLength
+}

src/lib.rs

@@ -1 +1,2 @@
 pub mod dsl;
+pub mod midi;

src/midi/core.rs

@@ -0,0 +1,110 @@
+extern crate derive_more;
+use derive_more::{Mul, Add};
+use midly::{Smf, Header, live::LiveEvent, MidiMessage, num::u15};
+use std::convert::{TryFrom};
+
+use crate::dsl::dsl::{Group, Length, ModdedLength, BasicLength};
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct FlatNote {
+    // measured in ticks (128th notes), so it's easy to align to a midi grid
+    length: u8
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Add, Mul)]
+#[repr(transparent)]
+pub struct Tick(pub u128);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub enum EventType {
+    NoteOn,
+    NoteOff,
+    Tempo,
+    Signature
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Event {
+    tick: Tick,
+    event_type: EventType
+}
+
+// Events are supposed to be sorted.
+pub type EventGrid = Vec<Event>;
+
+static TICKS_PER_QUARTER_NOTE : u16 = 48;
+
+fn basic_length_to_ticks(basic_length: BasicLength) -> Tick {
+    match basic_length {
+        BasicLength::Whole => Tick((TICKS_PER_QUARTER_NOTE * 4) as u128),
+        BasicLength::Half => Tick((TICKS_PER_QUARTER_NOTE * 2) as u128),
+        BasicLength::Fourth => Tick(TICKS_PER_QUARTER_NOTE as u128),
+        BasicLength::Eighth => Tick((TICKS_PER_QUARTER_NOTE / 2) as u128),
+        BasicLength::Sixteenth => Tick((TICKS_PER_QUARTER_NOTE / 4) as u128),
+        BasicLength::ThirtySecond => Tick((TICKS_PER_QUARTER_NOTE / 8) as u128),
+        BasicLength::SixtyFourth => Tick((TICKS_PER_QUARTER_NOTE / 16) as u128),
+    }
+}
+
+fn modded_length_to_ticks(modded_length: ModdedLength) -> Tick {
+    match modded_length {
+        ModdedLength::Plain(blen) => basic_length_to_ticks(blen),
+        ModdedLength::Dotted(blen) => {
+            let Tick(whole) = basic_length_to_ticks(blen);
+            let half = whole / 2;
+            Tick(whole + half)
+        }
+    }
+}
+
+fn length_to_ticks(length: Length) -> Tick {
+    match length {
+        Length::Simple(mlen) => modded_length_to_ticks(mlen),
+        Length::Tied(first, second) => modded_length_to_ticks(first) + modded_length_to_ticks(second),
+        Length::Triplet(mlen) => {
+            let Tick(straight) = modded_length_to_ticks(mlen);
+            let triplet = straight * 2 / 3;
+            Tick(triplet)
+        }
+    }
+}
+
+fn flatten_group(Group { notes, length, times }: Group, start: Tick) -> EventGrid {
+    let mut time = start;
+    let note_length = length_to_ticks(length);
+    let mut grid = Vec::new();
+    let ticks = length_to_ticks(length);
+    for entry in notes.iter() { |entry|
+        match entry {
+            crate::dsl::dsl::GroupOrNote::SingleGroup(_) => todo!(),
+            crate::dsl::dsl::GroupOrNote::SingleNote(Rest) => { time = time + note_length },
+            crate::dsl::dsl::GroupOrNote::SingleNote(Hit) => {
+                let note_end = time + note_length;
+                let note_on = Event { tick: time, event_type: EventType::NoteOn };
+                let note_off = Event { tick: note_end, event_type: EventType::NoteOff };
+                grid.push(note_on);
+                grid.push(note_off);
+                time = note_end;
+            },
+        };
+    }
+    grid.repeat(times.0 as usize)
+}
+
+fn flatten_groups(groups: Vec<Group>) -> EventGrid {
+    let mut out : EventGrid = Vec::new();
+    groups.iter().flat_map(|Group { notes, length, times }| {
+
+    }).collect()
+}
+
+
+// The length of a beat is not standard, so in order to fully describe the length of a MIDI tick the MetaMessage::Tempo event should be present.
+fn create_smf<'a>() -> Smf<'a> {
+    let tracks = vec![]; // FIXME
+    // https://majicdesigns.github.io/MD_MIDIFile/page_timing.html
+    // says " If it is not specified the MIDI default is 48 ticks per quarter note."
+    // As it's required in `Header`, let's use the same value.
+    let metrical = midly::Timing::Metrical(u15::new(TICKS_PER_QUARTER_NOTE.clone()));
+    Smf { header: Header { format: midly::Format::Parallel, timing: metrical }, tracks: tracks }
+}

src/midi/mod.rs

@@ -0,0 +1 @@
+pub mod core;