tonal-abc-notation/build/es5.js

Conversion between notes in ABC and scientific notation

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

var tonalNote = require('tonal-note');

/**
 * [![npm version](https://img.shields.io/npm/v/tonal-abc-notation.svg?style=flat-square)](https://www.npmjs.com/package/tonal-abc-notation)
 *
 * Convert note strings between ABC and scientific notation
 *
 * This is part of [tonal](https://www.npmjs.com/package/tonal) music theory library.
 *
 * @example
 * const Abc = require("tonal-abc-notation")
 * Abc.toNote("c") // => "C5"
 * Abc.toAbc("Db2") // =>  "_D,,"
 *
 * @example
 * import Tonal from "tonal"
 * import { toAbc } from "tonal-abc-notation"
 * Tonal.Scale.notes("C major").map(toAbc);
 *
 * @module Abc
 */

var REGEX = /^(_{1,}|=|\^{1,}|)([abcdefgABCDEFG])([,']*)$/;
var fillStr = function (s, n) { return Array(n + 1).join(s); };

function tokenize(str) {
  var m = REGEX.exec(str);
  if (!m) { return ["", "", ""]; }
  return [m[1], m[2], m[3]];
}

/**
 * Convert a (string) note in ABC notation into a (string) note in scientific notation
 *
 * @param {string} abcNote - the note in ABC notation
 * @return {string} the note in scientific notation of null if not valid
 * @example
 * Abc.toNote("c") // => "C5"
 */
function toNote(str) {
  var ref = tokenize(str);
  var acc = ref[0];
  var letter = ref[1];
  var oct = ref[2];
  if (letter === "") { return null; }
  var o = 4;
  for (var i = 0; i < oct.length; i++) { o += oct[i] === "," ? -1 : 1; }
  var a =
    acc[0] === "_"
      ? acc.replace(/_/g, "b")
      : acc[0] === "^"
        ? acc.replace(/\^/g, "#")
        : "";
  return letter.charCodeAt(0) > 96
    ? letter.toUpperCase() + a + (o + 1)
    : letter + a + o;
}

/**
 * Convert a (string) note in scientific notation into a (string) note in ABC notation
 *
 * @param {string} note - a note in scientific notation
 * @return {string} the note in ABC notation or null if not valid note
 * @example
 * abc.toAbc("C#4") // => "^C"
 */
function toAbc(str) {
  var ref = tonalNote.props(str);
  var letter = ref.letter;
  var acc = ref.acc;
  var oct = ref.oct;
  var a = acc[0] === "b" ? acc.replace(/b/g, "_") : acc.replace(/#/g, "^");
  var l = oct > 4 ? letter.toLowerCase() : letter;
  var o =
    oct === 5 ? "" : oct > 4 ? fillStr("'", oct - 5) : fillStr(",", 4 - oct);
  return a + l + o;
}

exports.tokenize = tokenize;
exports.toNote = toNote;
exports.toAbc = toAbc;