Parse

Meantonal provides some classes to parse to and from common formats:

• SPN handles Scientific Pitch Notation
• LilyPond handles LilyPond strings.
• Helmholtz handles Helmholtz Pitch Notation.
• ABC handles ABC notation.

Each provides static toPitch and fromPitch methods to convert between strings and Pitch vectors.

Note

These helper classes are not robust enough to be used to parse LilyPond or ABC files directly. They are just for enterring and printing Pitch names in familiar formats.

SPN

toPitch

static toPitch(spn: string): Pitch;

Creates a Pitch vector from a Scientific Pitch Notation string.

let p = SPN.toPitch("C#4");

fromPitch

static fromPitch(p: Pitch): string;

Returns the SPN name of a Pitch. Throws an error if the Pitch’s accidental is altered by more than 8 sharps/flats — an arbitrary limit chosen to avoid handling strings of unbounded size, and because exceeding it almost certainly indicates a logic error upstream.

let p = SPN.toPitch("C#4");
SPN.fromPitch(p); // "C#4"

p = Pitch.fromChroma(63, 4); // an extreme accidental (+9), unlikely from real usage
SPN.fromPitch(p); // Error: Cannot render SPN name: accidental (9) exceeds the maximum of ±8 sharps/flats.

LilyPond

toPitch

static toPitch(str: string): Pitch;

Creates a Pitch vector from a LilyPond note name.

let p = LilyPond.toPitch("cis'");

fromPitch

static fromPitch(p: Pitch): string;

Returns the (absolute) LilyPond name of a Pitch. Throws an error if the Pitch’s accidental goes beyond a double sharp/flat, or if its octave falls outside -3 to 11 (a healthy margin beyond the range of human hearing). LilyPond can’t represent either case, and both almost always indicate a logic error upstream.

let p = LilyPond.toPitch("cis'");
LilyPond.fromPitch(p); // "cis'"

p = Pitch.fromChroma(21, 4); // accidental of +3, beyond LilyPond's double sharp
LilyPond.fromPitch(p); // Error: Cannot render LilyPond name: accidental (3) exceeds the double sharp/flat limit (±2).

relative

static relative(start: Pitch): RelativeParser;

Returns a new instance of a relative mode LilyPond parser, with a .toPitch method that works exactly like the LilyPond.toPitch static method, but positioning each Pitch relative to the most recently parsed Pitch, before adjusting via octave marks.

let p = SPN.toPitch("C4");
let parser = LilyPond.relative(p);

p = parser.toPitch("g");   // G3, since it's the nearest G to C4
p = parser.toPitch("fis"); // F#3, since it's the nearest F# to G3
p = parser.toPitch("d'");  // D4, since the ' mark adjusts the octave by +1

Relative mode is often more convenient to reason around when entering pitches by hand.

Helmholtz

toPitch

static toPitch(str: string): Pitch;

Creates a Pitch vector from a Helmholtz note name.

let p = Helmholtz.toPitch("c#'");

fromPitch

static fromPitch(p: Pitch): string;

Returns the Helmholtz note name of a Pitch. Throws an error if the Pitch’s accidental is altered by more than 8 sharps/flats — an arbitrary limit chosen to avoid handling strings of unbounded size, and because it almost always indicates a logic error upstream.

let p = Helmholtz.toPitch("c#'");
Helmholtz.fromPitch(p); // "c#'"

p = Pitch.fromChroma(70, 4); // an extreme accidental (+10), unlikely from real usage
Helmholtz.fromPitch(p); // Error: Cannot render Helmholtz name: accidental (10) exceeds the maximum of ±8 sharps/flats.

ABC

toPitch

static toPitch(str: string): Pitch;

Creates a Pitch vector from an ABC note name.

let p = ABC.toPitch("^c'");

fromPitch

static fromPitch(p: Pitch): string;

Returns the ABC note name of a Pitch. Throws an error if the Pitch’s accidental goes beyond a double sharp/flat, or if its octave falls outside -3 to 11 (a healthy margin beyond the range of human hearing). ABC notation can’t represent either case, and both almost always indicate a logic error upstream.

let p = ABC.toPitch("^c'");
ABC.fromPitch(p); // "^c'"

p = Pitch.fromChroma(21, 4); // accidental of +3, beyond ABC's double sharp
ABC.fromPitch(p); // Error: Cannot render ABC name: accidental (3) exceeds the double sharp/flat limit (±2).