sim_lib_pitch_serial/
interval.rs

1//! Directed ordered-interval analysis for strict tone rows and row segments.
2
3use sim_lib_pitch_core::PitchClass;
4
5use crate::{RowFamily, ToneRow};
6
7/// The directed ordered intervals between adjacent pitches in source order.
8///
9/// Values are modulo-twelve semitone distances in `0..12`, so they preserve
10/// the row's ordinal contour without collapsing inversional complements.
11#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
12pub struct OrderedIntervalString {
13    intervals: [u8; 11],
14}
15
16impl OrderedIntervalString {
17    /// Computes the directed ordered intervals for `row`.
18    pub fn of_row(row: &ToneRow) -> Self {
19        Self {
20            intervals: ordered_intervals(row.classes()),
21        }
22    }
23
24    /// Returns the eleven directed intervals in source order.
25    pub const fn intervals(&self) -> &[u8; 11] {
26        &self.intervals
27    }
28
29    /// Returns the ordered-interval string implied by a row-family operation.
30    ///
31    /// Prime preserves order and direction, inversion negates every interval,
32    /// retrograde reverses the order and negates the direction, and
33    /// retrograde-inversion reverses the order only.
34    pub const fn under_family(self, family: RowFamily) -> Self {
35        let mut intervals = self.intervals;
36        match family {
37            RowFamily::P => {}
38            RowFamily::I => {
39                let mut index = 0;
40                while index < intervals.len() {
41                    intervals[index] = (12 - intervals[index]) % 12;
42                    index += 1;
43                }
44            }
45            RowFamily::R => {
46                intervals.reverse();
47                let mut index = 0;
48                while index < intervals.len() {
49                    intervals[index] = (12 - intervals[index]) % 12;
50                    index += 1;
51                }
52            }
53            RowFamily::RI => intervals.reverse(),
54        }
55        Self { intervals }
56    }
57}
58
59pub(crate) fn ordered_intervals(classes: &[PitchClass]) -> [u8; 11] {
60    debug_assert_eq!(classes.len(), 12);
61    std::array::from_fn(|index| {
62        (12 + i16::from(classes[index + 1].value()) - i16::from(classes[index].value())) as u8 % 12
63    })
64}
65
66pub(crate) fn ordered_intervals_vec(classes: &[PitchClass]) -> Vec<u8> {
67    classes
68        .windows(2)
69        .map(|window| (12 + i16::from(window[1].value()) - i16::from(window[0].value())) as u8 % 12)
70        .collect()
71}
sim_lib_pitch_serial/interval.rs

sim_lib_pitch_serial/
interval.rs
