gtfs2lc/lib/Connections2JSONLD.js

Mapping script from gtfs to (linked) connections

/**
 * Pieter Colpaert © Ghent University - iMinds 
 * Combines connection rules, trips and services to an unsorted stream of connections
 */
var Transform = require('stream').Transform,
  util = require('util'),
  URIStrategy = require('./URIStrategy.js');

var Connections2JSONLD = function (baseUris, context) {
  Transform.call(this, { objectMode: true });
  this._contextStreamed = false;
  this._context = context;

  // Skip context if none provided
  if (!this._context) {
    this._contextStreamed = true;
  }

  this._uris = new URIStrategy(baseUris);
  this._count = 0;
};

util.inherits(Connections2JSONLD, Transform);

Connections2JSONLD.prototype._transform = function (connection, encoding, done) {
  try {
    if (!this._contextStreamed) {
      this._contextStreamed = true;
      this.push(this._context);
    }

    var id = this._uris.getId(connection);
    const types = ['gtfs:Regular', 'gtfs:NotAvailable', 'gtfs:MustPhone', 'gtfs:MustCoordinateWithDriver'];

    var lc = {
      "@id": id,
      "@type": "Connection",
      "departureStop": this._uris.getStopId(connection.departureStop),
      "arrivalStop": this._uris.getStopId(connection.arrivalStop),
      "departureTime": connection.departureTime,
      "arrivalTime": connection.arrivalTime,
      "gtfs:trip": this._uris.getTripId(connection),
      "gtfs:route": this._uris.getRouteId(connection)
    };

    // the headsign is already the result here of earlier checking whether there’s a trip headsign 
    // or a route headsign if connection headsign was not set. It can be used reliably
    if (connection.headsign) {
      lc["direction"] = connection.headsign;
    }

    var pickupType = types[0];
    if (connection['pickup_type'] && connection['pickup_type'] !== null) {
      pickupType = types[connection['pickup_type']];
      lc["gtfs:pickupType"] = pickupType;
    }

    var dropOffType = types[0];
    if (connection['drop_off_type'] && connection['drop_off_type'] !== null) {
      dropOffType = types[connection['drop_off_type']];
      lc["gtfs:dropOffType"] = dropOffType;
    }

    this.push(lc);
    done();
  } catch (err) {
    done(null, {});
  }
};

module.exports = Connections2JSONLD;