composer/src/tone.rs

#[derive(Debug, PartialEq, Clone)]
pub struct Tone(i32);

// new parses [a-g][+-]?[1-5]? to tone, sharp or flat, down 2 octave..up 1 octave
pub fn new<S: ToString>(s: S) -> Tone {
    Tone::new(s.to_string())
}

impl Tone {
    fn new(s: String) -> Tone {
        let re = regex::Regex::new(r"^(((?<letter>^[a-g])(?<sharpness>[+-]?)|(?<major>[A-G]M[0-6])|(?<minor>[A-G]m[0-6]))(?<octave>[1-5]?)|(?<numeric>[0-9]+)|(?<rest>[^a-gA-G0-9]))$").unwrap();
        let captures = re
            .captures(&s)
            .expect(format!("tone '{}' does not match regex", s).as_ref());
        Tone(match captures.name("numeric") {
            Some(number) => number.as_str().parse::<i32>().unwrap(),
            None => match captures.name("rest") {
                Some(_) => 0,
                _ => {
                    let mut result = match captures.name("letter") {
                        Some(letter) => Tone::char_to_middle_i32(letter.as_str()),
                        None => match captures.name("major") {
                            Some(major) => Tone::char_to_middle_i32(&major.as_str()[..1]) + match &major.as_str()[2..] {
                                "0" => 0,
                                "1" => 2,
                                "2" => 4,
                                "3" => 5,
                                "4" => 7,
                                "5" => 9,
                                _ => 11,
                            },
                            None => {
                                let minor = captures.name("minor").unwrap();
                                Tone::char_to_middle_i32(&minor.as_str()[..1]) + match &minor.as_str()[2..] {
                                    "0" => 0,
                                    "1" => 2,
                                    "2" => 3,
                                    "3" => 5,
                                    "4" => 7,
                                    "5" => 8,
                                    _ => 10,
                                }
                            },
                        },
                    } as i32;

                    result += match captures.name("sharpness") {
                        Some(sharpness) => match sharpness.as_str() {
                            "+" => 1,
                            "-" => -1,
                            _ => 0,
                        },
                        None => 0,
                    } as i32;

                    result += match captures.name("octave") {
                        Some(octave) => match octave.as_str() {
                            "" => 0,
                            _ => (octave.as_str().parse::<i32>().unwrap() - 3) * 12,
                        },
                        None => 0,
                    } as i32;

                    result
                }
            },
        })
    }

    fn char_to_middle_i32(c: &str) -> i32 {
        match c.to_lowercase().as_str() {
            "a" => 57,
            "b" => 59,
            "c" => 60,
            "d" => 62,
            "e" => 64,
            "f" => 65,
            _ => 67,
        }
    }

    pub fn i32(&self) -> i32 {
        self.0
    }

    pub fn string(&self) -> String {
        let v = self.i32();
        let modifier = if v > 0 && v < 57 { "-" } else if v >= 69 { "+" } else { "" };
        modifier.to_string() + match v {
            45|57|69 => "a",
            46|58|70 => "a+",
            47|59|71 => "b",
            48|60|72 => "c",
            49|61|73 => "c+",
            50|62|74 => "d",
            51|63|75 => "d+",
            52|64|76 => "e",
            53|65|77 => "f",
            54|66|78 => "f+",
            55|67|79 => "g",
            56|68|80 => "g+",
            0 => " ",
            _ => "?",
        }
    }
}

#[cfg(test)]
mod test {
    #[test]
    fn test_tone_new() {
        eprintln!("numeric");
        assert_eq!(super::new("60").i32(), 60);

        eprintln!("rests");
        assert_eq!(super::new("-").i32(), 0);
        assert_eq!(super::new(".").i32(), 0);

        eprintln!("alpha");
        assert_eq!(super::new("c").i32(), 60);
        assert_eq!(super::new("e").i32(), 64);
        assert_eq!(super::new("g").i32(), 67);

        eprintln!("alpha mod");
        assert_eq!(super::new("c+").i32(), 60 + 1);
        assert_eq!(super::new("c-").i32(), 60 - 1);

        eprintln!("alpha octave");
        assert_eq!(super::new("c3").i32(), 60);
        assert_eq!(super::new("c4").i32(), 60 + 12);

        eprintln!("alpha mod octave");
        assert_eq!(super::new("c+4").i32(), 60 + 12 + 1);
    }

    #[test]
    fn test_tone_c_major() {
        assert_eq!(super::new("CM0"), super::new("c"));
        assert_eq!(super::new("CM1"), super::new("d"));
        assert_eq!(super::new("CM2"), super::new("e"));
        assert_eq!(super::new("CM3"), super::new("f"));
        assert_eq!(super::new("CM4"), super::new("g"));
        assert_eq!(super::new("CM5"), super::new("a4"));
        assert_eq!(super::new("CM6"), super::new("b4"));
    }

    #[test]
    fn test_tone_c_minor() {
        assert_eq!(super::new("Cm0"), super::new("c"));
        assert_eq!(super::new("Cm1"), super::new("d"));
        assert_eq!(super::new("Cm2"), super::new("e-"));
        assert_eq!(super::new("Cm3"), super::new("f"));
        assert_eq!(super::new("Cm4"), super::new("g"));
        assert_eq!(super::new("Cm5"), super::new("a-4"));
        assert_eq!(super::new("Cm6"), super::new("b-4"));
    }

    #[test]
    fn test_tone_a_major() {
        assert_eq!(super::new("AM0"), super::new("a"));
        assert_eq!(super::new("AM1"), super::new("b"));
        assert_eq!(super::new("AM2"), super::new("c+"));
        assert_eq!(super::new("AM3"), super::new("d"));
        assert_eq!(super::new("AM4"), super::new("e"));
        assert_eq!(super::new("AM5"), super::new("f+"));
        assert_eq!(super::new("AM6"), super::new("g+"));
    }

    #[test]
    fn test_tone_a_minor() {
        assert_eq!(super::new("Am0"), super::new("a"));
        assert_eq!(super::new("Am1"), super::new("b"));
        assert_eq!(super::new("Am2"), super::new("c"));
        assert_eq!(super::new("Am3"), super::new("d"));
        assert_eq!(super::new("Am4"), super::new("e"));
        assert_eq!(super::new("Am5"), super::new("f"));
        assert_eq!(super::new("Am6"), super::new("g"));
    }
}