node-nlp/lib/nlp/tokenizers/aggressive-tokenizer-en.js

Library for NLU (Natural Language Understanding) done in Node.js

/*
 * Copyright (c) AXA Shared Services Spain S.A.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

const AggressiveTokenizer = require('./aggressive-tokenizer');

class AggressiveTokenizerEn extends AggressiveTokenizer {
  replace(text) {
    let result = text.replace(/n't([ ,:;.!?]|$)/gi, ' not ');
    result = result.replace(/'s([ ,:;.!?]|$)/gi, ' is ');
    result = result.replace(/'re([ ,:;.!?]|$)/gi, ' are ');
    result = result.replace(/'ve([ ,:;.!?]|$)/gi, ' have ');
    result = result.replace(/'m([ ,:;.!?]|$)/gi, ' am ');
    result = result.replace(/'d([ ,:;.!?]|$)/gi, ' had ');
    return result;
  }

  replaceContractions(arr) {
    const contractionsBase = {
      cannot: ['can', 'not'],
      gonna: ['going', 'to'],
      wanna: ['want', 'to'],
    };

    const result = [];
    arr.forEach(item => {
      const lowitem = item.toLowerCase();
      if (contractionsBase[lowitem]) {
        result.push(...contractionsBase[lowitem]);
      } else {
        result.push(item);
      }
    });
    return result;
  }

  tokenize(text) {
    const replaced = this.replace(text);
    const arr = this.trim(replaced.split(/\W+/));
    return this.replaceContractions(arr, text);
  }
}

module.exports = AggressiveTokenizerEn;