compromise/src/term/noun/inflect/toSingle.js

natural language processing in the browser

'use strict';
const irregulars = require('../../paths').data.irregular_plurals.toSingle;
const singleRules = require('./data/singleRules');

//turn 'shoes' into 'shoe'
const toSingle = function (str) {
  //irregular
  if (irregulars[str]) {
    return irregulars[str];
  }
  //inflect first word of preposition-phrase
  if (str.match(/([a-z]*) (of|in|by|for) [a-z]/)) {
    const first = (str.match(/^([a-z]*) (of|in|by|for) [a-z]/) || [])[1];
    if (first) {
      const better_first = toSingle(first); //recursive
      return better_first + str.replace(first, '');
    }
  }

  //regular rule-based inflector
  for (let i = 0; i < singleRules.length; i++) {
    if (str.match(singleRules[i].reg)) {
      return str.replace(singleRules[i].reg, singleRules[i].repl);
    }
  }
  return null;
};

// console.log(toSingle('gases') === 'gas')
module.exports = toSingle;
// console.log(toSingle('days'))