chords 0.2.7

library for getting chords from scale
Documentation 
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use crate::util;

#[derive(PartialEq, Clone, Copy)]
pub enum Scale {
    Major,
    Minor,
    Harmonicminor,
    Melodicminor,
    Dorian,
    Phrygian,
    Lydian,
    Locrian,
    Mixolydian,
    Overtone,
    Augmented,
    Wholetone,
    Pentatonic,
    Chromatic,
}

impl Into<String> for Scale {
    fn into(self) -> String {
        match self {
            Scale::Major => "major",
            Scale::Minor => "minor",
            Scale::Harmonicminor => "harmonicminor",
            Scale::Melodicminor => "melodicminor",
            Scale::Dorian => "dorian",
            Scale::Phrygian => "phrygian",
            Scale::Lydian => "lydian",
            Scale::Locrian => "locrian",
            Scale::Mixolydian => "mixolydian",
            Scale::Overtone => "overtone",
            Scale::Augmented => "augmented",
            Scale::Wholetone => "wholetone",
            Scale::Pentatonic => "pentatonic",
            Scale::Chromatic => "chromatic",
        }
        .into()
    }
}

impl From<String> for Scale {
    fn from(s: String) -> Self {
        match &s[..] {
            "major" => Scale::Major,
            "minor" => Scale::Minor,
            "harmonicminor" => Scale::Harmonicminor,
            "melodicminor" => Scale::Melodicminor,
            "dorian" => Scale::Dorian,
            "phrygian" => Scale::Phrygian,
            "lydian" => Scale::Lydian,
            "locrian" => Scale::Locrian,
            "mixolydian" => Scale::Mixolydian,
            "overtone" => Scale::Overtone,
            "augmented" => Scale::Augmented,
            "wholetone" => Scale::Wholetone,
            "pentatonic" => Scale::Pentatonic,
            _ => Scale::Chromatic,
        }
    }
}

// Returns all notes on chromatic scale
pub fn chromatic_notes(root: (char, i8)) -> Vec<(char, i8)> {
    let mut v = vec![];

    // a
    v.push(('a', 0));
    // a sharp
    v.push(('a', 1));
    // b
    v.push(('b', 0));
    // c
    v.push(('c', 0));
    // c sharp
    v.push(('c', 1));
    // d
    v.push(('d', 0));
    // d sharp
    v.push(('d', 1));
    // e
    v.push(('e', 0));
    // f
    v.push(('f', 0));
    // f sharp
    v.push(('f', 1));
    // g
    v.push(('g', 0));
    // g sharp
    v.push(('g', 1));

    // Split and join according to root note
    let root_index = v
        .iter()
        .position(|&note| note == root || note == util::alt_note(root))
        .unwrap();
    let a = v[..root_index].to_vec();
    let b = v[root_index..].to_vec();

    let mut v = vec![];

    v.extend(b);
    v.extend(a);

    v
}

pub fn print_supported_scales() {
    println!("Supported scales:");
    for scale in supported_scales() {
        println!("\t{}", scale);
    }
    println!("Custom scale syntax: --scale 1,2,1,3,2,1");
}

pub fn supported_scales() -> Vec<String> {
    vec![
        "major",
        "minor",
        "harmonicminor",
        "melodicminor",
        "dorian",
        "phrygian",
        "lydian",
        "locrian",
        "mixolydian",
        "overtone",
        "augmented",
        "wholetone",
        "pentatonic",
    ]
    .iter()
    .map(|s| s.to_string())
    .collect()
}

/// Returns scales by name
pub fn get_scale(scale: &str) -> Vec<u8> {
    vec_sum(match scale {
        "major" | "ionian" => vec![2, 2, 1, 2, 2, 2, 1],
        "minor" | "naturalminor" | "aeolian" => vec![2, 1, 2, 2, 1, 2, 2],
        "harmonicminor" => vec![2, 1, 2, 2, 1, 3, 1],
        "melodicminor" => vec![2, 1, 2, 2, 2, 2],
        "dorian" => vec![2, 1, 2, 2, 2, 1, 2],
        "phrygian" => vec![1, 2, 2, 2, 1, 2, 2],
        "lydian" => vec![2, 2, 2, 1, 2, 2, 1],
        "locrian" => vec![1, 2, 2, 1, 2, 2, 2],
        "mixolydian" => vec![2, 2, 1, 2, 2, 1, 2],
        "overtone" => vec![2, 2, 2, 1, 2, 1],
        "augmented" => vec![1, 3, 1, 3, 1],
        "wholetone" => vec![2, 2, 2, 2, 2, 2],
        "pentatonic" => vec![2, 2, 3, 2],
        "chromatic" => vec![1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
        _ => parse_scale(scale),
    })
}

// Parses scale from "1,1,..." format
fn parse_scale(scalestr: &str) -> Vec<u8> {
    scalestr
        .split(",")
        .map(|s| s.parse::<u8>().unwrap_or(1))
        .collect()
}

/// Returns array of summed items
fn vec_sum(interval: Vec<u8>) -> Vec<u8> {
    let mut vec: Vec<u8> = vec![0];
    vec.extend(interval.into_iter().scan(0, |sum, step| {
        *sum = *sum + step;
        Some(*sum)
    }));
    vec
}

pub fn friendly_name(name: &str) -> String {
    String::from(match name {
        "major" => "Major",
        "minor" | "naturalminor" => "Natural minor",
        "hmin" | "harmonicminor" => "Harmonic minor",
        "augmented" => "Augmented",
        "wholetone" => "Wholetone",
        "melodicminor" => "Melodic minor",
        "overtone" => "Overtone",
        "chromatic" => "Chromatic",
        _ => name,
    })
}