talisman/phonetics/german/cologne.js

Straightforward fuzzy matching, information retrieval and NLP building blocks for JavaScript.

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = cologne;

var _helpers = require('../../helpers');

var _deburr = require('lodash/deburr');

var _deburr2 = _interopRequireDefault(_deburr);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/**
 * Maps.
 */
/**
 * Talisman phonetics/german/cologne
 * ==================================
 *
 * The cologne algorithm.
 *
 * [Reference]:
 * https://en.wikipedia.org/wiki/Cologne_phonetics
 *
 * [Article]:
 * Hans Joachim Postel: Die Kölner Phonetik. Ein Verfahren zur Identifizierung
 * von Personennamen auf der Grundlage der Gestaltanalyse.
 * in: IBM-Nachrichten, 19. Jahrgang, 1969, S. 925-931.
 */
var CODES = {
  H: null,

  A: 0,
  E: 0,
  I: 0,
  O: 0,
  U: 0,
  J: 0,
  Y: 0,

  B: 1,
  P: 1,

  F: 3,
  V: 3,
  W: 3,

  G: 4,
  K: 4,
  Q: 4,

  L: 5,

  M: 6,
  N: 6,

  R: 7,

  S: 8,
  Z: 8
};

var DT = new Set(['C', 'S', 'Z']),
    CFollowing1 = new Set(['A', 'H', 'K', 'L', 'O', 'Q', 'R', 'U', 'X']),
    CFollowing2 = new Set(['A', 'H', 'K', 'O', 'Q', 'U', 'X']),
    CPrevious = new Set(['S', 'Z']),
    X = new Set(['C', 'Q', 'K']);

/**
 * Helpers.
 */
function germanicSubstitutions(name) {
  return name.replace(/Ä/g, 'A').replace(/Ö/g, 'O').replace(/Ü/g, 'U').replace(/ß/g, 'SS').replace(/PH/g, 'F');
}

/**
 * Function taking a single name and computing its cologne code.
 *
 * @param  {string}  name - The name to process.
 * @return {string}       - The cologne code.
 *
 * @throws {Error} The function expects the name to be a string.
 */
function cologne(name) {
  if (typeof name !== 'string') throw Error('talisman/phonetics/german/cologne: the given name is not a string.');

  // Preparing the name
  name = (0, _deburr2.default)(germanicSubstitutions(name.toUpperCase())).replace(/[^A-Z]/g, '');

  // Processing the letters of the name
  var code = [];

  for (var i = 0, l = name.length; i < l; i++) {
    var letter = name[i],
        possibleCode = CODES[letter];

    if (possibleCode !== undefined) code.push(possibleCode);

    // Handling D/T
    else if (letter === 'D' || letter === 'T') code.push(DT.has(name[i + 1]) ? 8 : 2);

      // Handling C
      else if (letter === 'C') {
          var previous = name[i - 1],
              following = name[i + 1];

          if (!previous && CFollowing1.has(following) || CFollowing2.has(following) && !CPrevious.has(previous)) {
            code.push(4);
          } else {
            code.push(8);
          }
        }

        // Handling X
        else if (letter === 'X') code.push(X.has(name[i - 1]) ? 8 : 48);
  }

  // Squeezing and dropping 0 if not first letter
  code = (0, _helpers.squeeze)(code).filter(function (letter, i) {
    return !i || letter;
  });

  return code.join('');
}
module.exports = exports['default'];