talisman/stemmers/latin/schinke.js

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

'use strict';

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

exports.default = function (word) {

  // Preparing the word
  var preparedWord = normalizeLetters(word.toLowerCase().replace(/[^a-z]/g, ''));

  // Dropping the -que suffix
  var stem = preparedWord.replace(/que$/, '');

  // Checking whether the word ends in -que & is a protected stem
  if (preparedWord !== stem && QUE_SET.has(preparedWord)) return {
    noun: preparedWord,
    verb: preparedWord
  };

  var nounStem = stem,
      verbStem = stem;

  // Computing the noun stem
  for (var i = 0, l = SIMPLE_SUFFIXES.length; i < l; i++) {
    var newStem = nounStem.replace(SIMPLE_SUFFIXES[i], '');

    if (newStem !== stem) {
      nounStem = newStem;
      break;
    }
  }

  // Computing the verb stem
  for (var _i = 0, _l = VERB_SUFFIXES.length; _i < _l; _i++) {
    var _VERB_SUFFIXES$_i = VERB_SUFFIXES[_i],
        match = _VERB_SUFFIXES$_i[0],
        replacement = _VERB_SUFFIXES$_i[1];


    if (match.test(verbStem)) {
      var pattern = new RegExp((replacement ? '(.{2,})' : '') + match.source);

      verbStem = verbStem.replace(pattern, replacement || '');
      break;
    }
  }

  // Returning the stem only if longer than one character
  return {
    noun: nounStem.length > 1 ? nounStem : stem,
    verb: verbStem.length > 1 ? verbStem : stem
  };
};

/**
 * Talisman stemmers/latin/schinke
 * ================================
 *
 * The Schinke stemming algorithm (latin).
 *
 * [Reference]:
 * http://snowball.tartarus.org/otherapps/schinke/intro.html
 */

/**
 * Rules.
 */
var QUE_SET = new Set(['atque', 'quoque', 'neque', 'itaque', 'absque', 'apsque', 'abusque', 'adaeque', 'adusque', 'denique', 'deque', 'susque', 'oblique', 'peraeque', 'plenisque', 'quandoque', 'quisque', 'quaeque', 'cuiusque', 'cuique', 'quemque', 'quamque', 'quaque', 'quique', 'quorumque', 'quarumque', 'quibusque', 'quosque', 'quasque', 'quotusquisque', 'quousque', 'ubique', 'undique', 'usque', 'uterque', 'utique', 'utroque', 'utribique', 'torque', 'coque', 'concoque', 'contorque', 'detorque', 'decoque', 'excoque', 'extorque', 'obtorque', 'optorque', 'retorque', 'recoque', 'attorque', 'incoque', 'intorque', 'praetorque']);

var SIMPLE_SUFFIXES = [/ibus$/, /ius$/, /ae$/, /am$/, /as$/, /em$/, /es$/, /ia$/, /is$/, /nt$/, /os$/, /ud$/, /um$/, /us$/, /a$/, /e$/, /i$/, /o$/, /u$/];

var VERB_SUFFIXES = [[/iuntur$/, '$1i'], [/erunt$/, '$1i'], [/untur$/, '$1i'], [/iunt$/, '$1i'], [/unt$/, '$1i'], [/beris$/, '$1bi'], [/bor$/, '$1bi'], [/bo$/, '$1bi'], [/ero$/, '$1eri'], [/mini$/], [/ntur$/], [/stis$/], [/mur$/], [/mus$/], [/ris$/], [/sti$/], [/tis$/], [/tur$/], [/ns$/], [/nt$/], [/ri$/], [/m$/], [/r$/], [/s$/], [/t$/]];

/**
 * Helpers.
 */
function normalizeLetters(stem) {
  return stem.replace(/j/g, 'i').replace(/v/g, 'u');
}

/**
 * Function stemming the given latin word using the Schinke algorithm and
 * returning a noun stem and a verb stem.
 *
 * @param  {string} word - The word to stem.
 * @return {objet}       - The resulting stems (noun & verb).
 */
module.exports = exports['default'];