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//! A module for working with mode kinds.
use crate::core::{
base::{HasDescription, HasName, HasStaticName},
interval::{HasIntervals, Interval},
scale_kind::ScaleKind,
};
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
// Enum.
/// An enum representing a mode kind (type of mode).
///
/// Each mode kind has an **explicit** list of intervals that define the mode.
/// These intervals are NOT derived by rotation - they are the authoritative definition.
/// Parent scale information is included for documentation purposes only.
#[derive(PartialEq, Eq, Copy, Clone, Hash, Debug, Ord, PartialOrd)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[repr(u8)]
pub enum ModeKind {
// Major scale modes (diatonic)
/// Ionian mode (1st mode of major scale).
Ionian,
/// Dorian mode (2nd mode of major scale).
Dorian,
/// Phrygian mode (3rd mode of major scale).
Phrygian,
/// Lydian mode (4th mode of major scale).
Lydian,
/// Mixolydian mode (5th mode of major scale).
Mixolydian,
/// Aeolian mode (6th mode of major scale).
Aeolian,
/// Locrian mode (7th mode of major scale).
Locrian,
// Harmonic minor modes
/// Locrian ♮6 mode (2nd mode of harmonic minor).
LocrianNatural6,
/// Ionian ♯5 mode (3rd mode of harmonic minor).
IonianSharp5,
/// Dorian ♯4 mode (4th mode of harmonic minor).
DorianSharp4,
/// Phrygian Dominant mode (5th mode of harmonic minor).
PhrygianDominant,
/// Lydian ♯2 mode (6th mode of harmonic minor).
LydianSharp2,
/// Ultralocrian mode (7th mode of harmonic minor).
Ultralocrian,
// Melodic minor modes
/// Dorian ♭2 mode (2nd mode of melodic minor).
DorianFlat2,
/// Lydian Augmented mode (3rd mode of melodic minor).
LydianAugmented,
/// Lydian Dominant mode (4th mode of melodic minor).
LydianDominant,
/// Mixolydian ♭6 mode (5th mode of melodic minor).
MixolydianFlat6,
/// Locrian ♮2 mode (6th mode of melodic minor).
LocrianNatural2,
/// Altered / Super Locrian mode (7th mode of melodic minor).
Altered,
}
// Impls.
impl ModeKind {
/// Returns the parent scale kind for this mode (for documentation only).
///
/// This is metadata - the intervals are NOT derived from the parent.
pub fn parent_scale(&self) -> ScaleKind {
match self {
ModeKind::Ionian | ModeKind::Dorian | ModeKind::Phrygian | ModeKind::Lydian | ModeKind::Mixolydian | ModeKind::Aeolian | ModeKind::Locrian => ScaleKind::Major,
ModeKind::LocrianNatural6 | ModeKind::IonianSharp5 | ModeKind::DorianSharp4 | ModeKind::PhrygianDominant | ModeKind::LydianSharp2 | ModeKind::Ultralocrian => ScaleKind::HarmonicMinor,
ModeKind::DorianFlat2 | ModeKind::LydianAugmented | ModeKind::LydianDominant | ModeKind::MixolydianFlat6 | ModeKind::LocrianNatural2 | ModeKind::Altered => ScaleKind::MelodicMinor,
}
}
/// Returns the degree of the parent scale that this mode starts on (for documentation only).
///
/// This is metadata - the intervals are NOT derived from the parent.
pub fn parent_degree(&self) -> u8 {
match self {
// Major scale modes
ModeKind::Ionian => 1,
ModeKind::Dorian => 2,
ModeKind::Phrygian => 3,
ModeKind::Lydian => 4,
ModeKind::Mixolydian => 5,
ModeKind::Aeolian => 6,
ModeKind::Locrian => 7,
// Harmonic minor modes
ModeKind::LocrianNatural6 => 2,
ModeKind::IonianSharp5 => 3,
ModeKind::DorianSharp4 => 4,
ModeKind::PhrygianDominant => 5,
ModeKind::LydianSharp2 => 6,
ModeKind::Ultralocrian => 7,
// Melodic minor modes
ModeKind::DorianFlat2 => 2,
ModeKind::LydianAugmented => 3,
ModeKind::LydianDominant => 4,
ModeKind::MixolydianFlat6 => 5,
ModeKind::LocrianNatural2 => 6,
ModeKind::Altered => 7,
}
}
}
impl HasIntervals for ModeKind {
fn intervals(&self) -> &'static [Interval] {
match self {
// MAJOR SCALE MODES
// Ionian: W-W-H-W-W-W-H (same as major scale)
ModeKind::Ionian => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MajorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MajorSixth,
Interval::MajorSeventh,
],
// Dorian: W-H-W-W-W-H-W (minor scale with raised 6th)
ModeKind::Dorian => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MinorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MajorSixth,
Interval::MinorSeventh,
],
// Phrygian: H-W-W-W-H-W-W (minor scale with lowered 2nd)
ModeKind::Phrygian => &[
Interval::PerfectUnison,
Interval::MinorSecond,
Interval::MinorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MinorSixth,
Interval::MinorSeventh,
],
// Lydian: W-W-W-H-W-W-H (major scale with raised 4th)
ModeKind::Lydian => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MajorThird,
Interval::AugmentedFourth,
Interval::PerfectFifth,
Interval::MajorSixth,
Interval::MajorSeventh,
],
// Mixolydian: W-W-H-W-W-H-W (major scale with lowered 7th)
ModeKind::Mixolydian => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MajorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MajorSixth,
Interval::MinorSeventh,
],
// Aeolian: W-H-W-W-H-W-W (natural minor scale)
ModeKind::Aeolian => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MinorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MinorSixth,
Interval::MinorSeventh,
],
// Locrian: H-W-W-H-W-W-W (diminished scale)
ModeKind::Locrian => &[
Interval::PerfectUnison,
Interval::MinorSecond,
Interval::MinorThird,
Interval::PerfectFourth,
Interval::DiminishedFifth,
Interval::MinorSixth,
Interval::MinorSeventh,
],
// HARMONIC MINOR MODES
// Locrian ♮6: H-W-W-H-W+H-W (Locrian with natural 6th)
// Example: B Locrian ♮6 = B C D E F G♯ A
ModeKind::LocrianNatural6 => &[
Interval::PerfectUnison,
Interval::MinorSecond,
Interval::MinorThird,
Interval::PerfectFourth,
Interval::DiminishedFifth,
Interval::MajorSixth,
Interval::MinorSeventh,
],
// Ionian ♯5: W-W-H-W+H-H-H (Major with augmented 5th)
// Example: C Ionian ♯5 = C D E F G♯ A B
ModeKind::IonianSharp5 => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MajorThird,
Interval::PerfectFourth,
Interval::AugmentedFifth,
Interval::MajorSixth,
Interval::MajorSeventh,
],
// Dorian ♯4: W-H-W+H-H-W-W (Dorian with augmented 4th)
// Example: D Dorian ♯4 = D E F G♯ A B C
ModeKind::DorianSharp4 => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MinorThird,
Interval::AugmentedFourth,
Interval::PerfectFifth,
Interval::MajorSixth,
Interval::MinorSeventh,
],
// Phrygian Dominant: H-W+H-H-W-H-W-W (Phrygian with major 3rd)
// Example: E Phrygian Dominant = E F G♯ A B C D
ModeKind::PhrygianDominant => &[
Interval::PerfectUnison,
Interval::MinorSecond,
Interval::MajorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MinorSixth,
Interval::MinorSeventh,
],
// Lydian ♯2: W+H-H-W-H-W-W-H (Lydian with augmented 2nd)
// Example: F Lydian ♯2 = F G♯ A B C D E
ModeKind::LydianSharp2 => &[
Interval::PerfectUnison,
Interval::AugmentedSecond,
Interval::MajorThird,
Interval::AugmentedFourth,
Interval::PerfectFifth,
Interval::MajorSixth,
Interval::MajorSeventh,
],
// Ultralocrian: H-W-H-W-W-W-W (Locrian ♭♭7)
// Example: G♯ Ultralocrian = G♯ A B C D E F
ModeKind::Ultralocrian => &[
Interval::PerfectUnison,
Interval::MinorSecond,
Interval::MinorThird,
Interval::DiminishedFourth,
Interval::DiminishedFifth,
Interval::MinorSixth,
Interval::DiminishedSeventh,
],
// MELODIC MINOR MODES
// Dorian ♭2 (Phrygian ♮6): H-W-W-W-W-W-H (Dorian with flat 2nd)
// Example: B Dorian ♭2 = B C D E F♯ G♯ A
ModeKind::DorianFlat2 => &[
Interval::PerfectUnison,
Interval::MinorSecond,
Interval::MinorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MajorSixth,
Interval::MajorSeventh,
],
// Lydian Augmented: W-W-W-W-H-W-H (Lydian with augmented 5th)
// Example: C Lydian Augmented = C D E F♯ G♯ A B
ModeKind::LydianAugmented => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MajorThird,
Interval::AugmentedFourth,
Interval::AugmentedFifth,
Interval::MajorSixth,
Interval::MajorSeventh,
],
// Lydian Dominant (Acoustic): W-W-W-H-W-H-W (Mixolydian with sharp 4th)
// Example: D Lydian Dominant = D E F♯ G♯ A B C
ModeKind::LydianDominant => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MajorThird,
Interval::AugmentedFourth,
Interval::PerfectFifth,
Interval::MajorSixth,
Interval::MinorSeventh,
],
// Mixolydian ♭6 (Aeolian Dominant): W-W-H-W-H-W-W (Mixolydian with flat 6th)
// Example: E Mixolydian ♭6 = E F♯ G♯ A B C D
ModeKind::MixolydianFlat6 => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MajorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MinorSixth,
Interval::MinorSeventh,
],
// Locrian ♮2 (Half-diminished): W-H-W-H-W-W-W (Locrian with natural 2nd)
// Example: F♯ Locrian ♮2 = F♯ G♯ A B C D E
ModeKind::LocrianNatural2 => &[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MinorThird,
Interval::PerfectFourth,
Interval::DiminishedFifth,
Interval::MinorSixth,
Interval::MinorSeventh,
],
// Altered (Super Locrian): H-W-H-W-W-W-W (All alterations)
// Example: G♯ Altered = G♯ A B C D E F♯
//
// Theoretical interval spelling from the melodic minor parent would be:
// 1, m2, A2, M3, dim5, dim6, m7
//
// However, we intentionally use enharmonic equivalents here:
// A2 → m3 (AugmentedSecond → MinorThird)
// M3 → dim4 (MajorThird → DiminishedFourth)
// dim6 → m6 (DiminishedSixth → MinorSixth)
//
// This keeps the internal interval representation free of double accidentals
// and avoids reusing the same letter name multiple times when combined with
// validate_spelling(), which checks for unique letter names. In other words,
// these spellings are chosen for practical spelling/validation reasons while
// remaining pitch‑equivalent to the theoretical Altered mode.
ModeKind::Altered => &[
Interval::PerfectUnison,
Interval::MinorSecond,
Interval::MinorThird,
Interval::DiminishedFourth,
Interval::DiminishedFifth,
Interval::MinorSixth,
Interval::MinorSeventh,
],
}
}
}
impl HasDescription for ModeKind {
fn description(&self) -> &'static str {
match self {
// Major scale modes
ModeKind::Ionian => "ionian, 1st mode of major scale, major scale",
ModeKind::Dorian => "dorian, 2nd mode of major scale, minor with raised 6th",
ModeKind::Phrygian => "phrygian, 3rd mode of major scale, minor with lowered 2nd",
ModeKind::Lydian => "lydian, 4th mode of major scale, major with raised 4th",
ModeKind::Mixolydian => "mixolydian, 5th mode of major scale, major with lowered 7th",
ModeKind::Aeolian => "aeolian, 6th mode of major scale, natural minor",
ModeKind::Locrian => "locrian, 7th mode of major scale, diminished, half-diminished chord scale",
// Harmonic minor modes
ModeKind::LocrianNatural6 => "locrian ♮6, 2nd mode of harmonic minor, m7♭5(♮13) color",
ModeKind::IonianSharp5 => "ionian ♯5, 3rd mode of harmonic minor, augmented major",
ModeKind::DorianSharp4 => "dorian ♯4, 4th mode of harmonic minor, minor with lydian bite",
ModeKind::PhrygianDominant => "phrygian dominant, 5th mode of harmonic minor, spanish phrygian",
ModeKind::LydianSharp2 => "lydian ♯2, 6th mode of harmonic minor, bright + exotic",
ModeKind::Ultralocrian => "ultralocrian, 7th mode of harmonic minor, very unstable/dark",
// Melodic minor modes
ModeKind::DorianFlat2 => "dorian ♭2, 2nd mode of melodic minor, phrygian ♮6, minor with spicy ♭2",
ModeKind::LydianAugmented => "lydian augmented, 3rd mode of melodic minor, lydian ♯5",
ModeKind::LydianDominant => "lydian dominant, 4th mode of melodic minor, acoustic scale, dominant with ♯11",
ModeKind::MixolydianFlat6 => "mixolydian ♭6, 5th mode of melodic minor, aeolian dominant, dominant with ♭13",
ModeKind::LocrianNatural2 => "locrian ♮2, 6th mode of melodic minor, half-diminished ♮2",
ModeKind::Altered => "altered, 7th mode of melodic minor, super locrian, V7alt scale",
}
}
}
impl HasStaticName for ModeKind {
fn static_name(&self) -> &'static str {
match self {
// Major scale modes
ModeKind::Ionian => "ionian",
ModeKind::Dorian => "dorian",
ModeKind::Phrygian => "phrygian",
ModeKind::Lydian => "lydian",
ModeKind::Mixolydian => "mixolydian",
ModeKind::Aeolian => "aeolian",
ModeKind::Locrian => "locrian",
// Harmonic minor modes
ModeKind::LocrianNatural6 => "locrian ♮6",
ModeKind::IonianSharp5 => "ionian ♯5",
ModeKind::DorianSharp4 => "dorian ♯4",
ModeKind::PhrygianDominant => "phrygian dominant",
ModeKind::LydianSharp2 => "lydian ♯2",
ModeKind::Ultralocrian => "ultralocrian",
// Melodic minor modes
ModeKind::DorianFlat2 => "dorian ♭2",
ModeKind::LydianAugmented => "lydian augmented",
ModeKind::LydianDominant => "lydian dominant",
ModeKind::MixolydianFlat6 => "mixolydian ♭6",
ModeKind::LocrianNatural2 => "locrian ♮2",
ModeKind::Altered => "altered",
}
}
}
impl HasName for ModeKind {
fn name(&self) -> String {
self.static_name().to_owned()
}
}
impl ModeKind {
/// Returns the ASCII name of the mode (using 'b', '#', 'nat' instead of Unicode symbols).
pub fn ascii_name(&self) -> &'static str {
match self {
// Major scale modes
ModeKind::Ionian => "ionian",
ModeKind::Dorian => "dorian",
ModeKind::Phrygian => "phrygian",
ModeKind::Lydian => "lydian",
ModeKind::Mixolydian => "mixolydian",
ModeKind::Aeolian => "aeolian",
ModeKind::Locrian => "locrian",
// Harmonic minor modes
ModeKind::LocrianNatural6 => "locrian nat6",
ModeKind::IonianSharp5 => "ionian #5",
ModeKind::DorianSharp4 => "dorian #4",
ModeKind::PhrygianDominant => "phrygian dominant",
ModeKind::LydianSharp2 => "lydian #2",
ModeKind::Ultralocrian => "ultralocrian",
// Melodic minor modes
ModeKind::DorianFlat2 => "dorian b2",
ModeKind::LydianAugmented => "lydian augmented",
ModeKind::LydianDominant => "lydian dominant",
ModeKind::MixolydianFlat6 => "mixolydian b6",
ModeKind::LocrianNatural2 => "locrian nat2",
ModeKind::Altered => "altered",
}
}
}
// Tests.
#[cfg(test)]
mod tests {
use super::*;
use pretty_assertions::assert_eq;
#[test]
fn test_mode_intervals_explicit() {
// All modes should have 7 notes
assert_eq!(ModeKind::Ionian.intervals().len(), 7);
assert_eq!(ModeKind::Dorian.intervals().len(), 7);
assert_eq!(ModeKind::Phrygian.intervals().len(), 7);
assert_eq!(ModeKind::Lydian.intervals().len(), 7);
assert_eq!(ModeKind::Mixolydian.intervals().len(), 7);
assert_eq!(ModeKind::Aeolian.intervals().len(), 7);
assert_eq!(ModeKind::Locrian.intervals().len(), 7);
// Ionian = Major
assert_eq!(
ModeKind::Ionian.intervals(),
&[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MajorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MajorSixth,
Interval::MajorSeventh,
]
);
// Dorian has characteristic major 6th in minor context
assert_eq!(
ModeKind::Dorian.intervals(),
&[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MinorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MajorSixth, // Characteristic raised 6th
Interval::MinorSeventh,
]
);
// Phrygian has characteristic minor 2nd
assert_eq!(
ModeKind::Phrygian.intervals(),
&[
Interval::PerfectUnison,
Interval::MinorSecond, // Characteristic lowered 2nd
Interval::MinorThird,
Interval::PerfectFourth,
Interval::PerfectFifth,
Interval::MinorSixth,
Interval::MinorSeventh,
]
);
// Lydian has characteristic augmented 4th
assert_eq!(
ModeKind::Lydian.intervals(),
&[
Interval::PerfectUnison,
Interval::MajorSecond,
Interval::MajorThird,
Interval::AugmentedFourth, // Characteristic raised 4th
Interval::PerfectFifth,
Interval::MajorSixth,
Interval::MajorSeventh,
]
);
// Locrian has characteristic diminished 5th
assert_eq!(
ModeKind::Locrian.intervals(),
&[
Interval::PerfectUnison,
Interval::MinorSecond,
Interval::MinorThird,
Interval::PerfectFourth,
Interval::DiminishedFifth, // Characteristic diminished 5th
Interval::MinorSixth,
Interval::MinorSeventh,
]
);
}
#[test]
fn test_mode_names() {
assert_eq!(ModeKind::Ionian.static_name(), "ionian");
assert_eq!(ModeKind::Dorian.static_name(), "dorian");
assert_eq!(ModeKind::Phrygian.static_name(), "phrygian");
assert_eq!(ModeKind::Lydian.static_name(), "lydian");
assert_eq!(ModeKind::Mixolydian.static_name(), "mixolydian");
assert_eq!(ModeKind::Aeolian.static_name(), "aeolian");
assert_eq!(ModeKind::Locrian.static_name(), "locrian");
}
#[test]
fn test_mode_parent_metadata() {
// All major scale modes have Major as parent
assert_eq!(ModeKind::Ionian.parent_scale(), ScaleKind::Major);
assert_eq!(ModeKind::Dorian.parent_scale(), ScaleKind::Major);
assert_eq!(ModeKind::Locrian.parent_scale(), ScaleKind::Major);
// Degrees should be 1-7
assert_eq!(ModeKind::Ionian.parent_degree(), 1);
assert_eq!(ModeKind::Dorian.parent_degree(), 2);
assert_eq!(ModeKind::Phrygian.parent_degree(), 3);
assert_eq!(ModeKind::Lydian.parent_degree(), 4);
assert_eq!(ModeKind::Mixolydian.parent_degree(), 5);
assert_eq!(ModeKind::Aeolian.parent_degree(), 6);
assert_eq!(ModeKind::Locrian.parent_degree(), 7);
}
#[test]
fn test_mode_descriptions() {
assert_eq!(ModeKind::Ionian.description(), "ionian, 1st mode of major scale, major scale");
assert_eq!(ModeKind::Dorian.description(), "dorian, 2nd mode of major scale, minor with raised 6th");
assert_eq!(ModeKind::Lydian.description(), "lydian, 4th mode of major scale, major with raised 4th");
}
}