How to use the lunr.Pipeline function in lunr

'use strict';

const lunr = require('lunr');
const {Builder: lunrBuilder, Index: lunrIndex} = lunr;
const path = require('path');
const fs = require('fs');
const async = require('async');

// customize Lunr so it normalizes punctuation
function fixToken(token) {
  const tokenString = token.toString();
  const rewrittenToken = tokenString.replace(/[\(\)\!\?\'\"#&’\.\[\]\{\}…\,”]/g, '');
  return rewrittenToken.length !== tokenString.length ? token.update(() => rewrittenToken) : token;
}

lunr.Pipeline.registerFunction(fixToken, 'normalizeTokens');

function normalizeTokens(builder) {
  builder.pipeline.add(fixToken);
  builder.searchPipeline.add(fixToken);
}

/**
 * An in-memory search engine implementation with file storage suitable for small sites.
 */
class LunrIndex {
  /**
   * Constructs a Lunr index from the provided id filter and map
   * @param {object} scope The scope.
   * @param {RegExp} [idFilter] A regular expression that validates content item ids before they are read and indexed.
   * @param {Function} map The map function takes a content item and returns an index entry, or null.
   * An index entry should have an id property. The index will automatically add an `id` property set to be the id of the item

buildIndex() {
    log.info('Splicing gym metadata and indexing gym data...');

    const gymsBase = require('PgP-Data/data/gyms'),
      gymsMetadata = require('PgP-Data/data/gyms-metadata'),
      mergedGyms = gymsBase
        .map(gym => Object.assign({}, gym, gymsMetadata[gym.gymId])),
      stopwordFilter = this.stopWordFilter,
      blacklistWordFilter = lunr.generateStopWordFilter(settings.blacklistWords);

    this.blacklistWordFilter = blacklistWordFilter;

    lunr.Pipeline.registerFunction(blacklistWordFilter, 'blacklistWords');
    lunr.Pipeline.registerFunction(stopwordFilter, 'customStopwords');

    this.gyms = new Map(mergedGyms
      .map(gym => [gym.gymId, gym]));

    this.regionMap = require('PgP-Data/data/region-map');
    this.regionGraph = require('PgP-Data/data/region-graph');

    this.index = lunr(function () {
      // reference will be the entire gym object so we can grab whatever we need from it (GPS coordinates, name, etc.)
      this.ref('object');

      // static fields for gym name, nickname, and description
      this.field('name');
      this.field('nickname');
      this.field('description');

buildIndex() {
    log.info('Splicing gym metadata and indexing gym data...');

    const gymsBase = require('PgP-Data/data/gyms'),
      gymsMetadata = require('PgP-Data/data/gyms-metadata'),
      mergedGyms = gymsBase
        .map(gym => Object.assign({}, gym, gymsMetadata[gym.gymId])),
      stopwordFilter = this.stopWordFilter,
      blacklistWordFilter = lunr.generateStopWordFilter(settings.blacklistWords);

    this.blacklistWordFilter = blacklistWordFilter;

    lunr.Pipeline.registerFunction(blacklistWordFilter, 'blacklistWords');
    lunr.Pipeline.registerFunction(stopwordFilter, 'customStopwords');

    this.gyms = new Map(mergedGyms
      .map(gym => [gym.gymId, gym]));

    this.regionMap = require('PgP-Data/data/region-map');
    this.regionGraph = require('PgP-Data/data/region-graph');

    this.index = lunr(function () {
      // reference will be the entire gym object so we can grab whatever we need from it (GPS coordinates, name, etc.)
      this.ref('object');

      // static fields for gym name, nickname, and description
      this.field('name');
      this.field('nickname');
      this.field('description');

constructor() {
    lunr.Pipeline.registerFunction(Gym.blacklistWordFilter, 'blacklistWords');
    lunr.Pipeline.registerFunction(Search.stopWordFilter, 'customStopwords');
  }

constructor() {
    lunr.Pipeline.registerFunction(Gym.blacklistWordFilter, 'blacklistWords');
    lunr.Pipeline.registerFunction(Search.stopWordFilter, 'customStopwords');
  }