overpass-frontend/src/SortedCallbacks.js

A JavaScript (NodeJS/Browser) library to easily access data from OpenStreetMap via Overpass API or from an OSM File. The objects can directly be used with LeafletJS or exported to GeoJSON. Data will be cached in the browser memory.

const async = require('async')
const weightSort = require('weight-sort')
const OverpassFrontend = require('./defines')

class SortedCallbacks {
  constructor (options, featureCallback, finalCallback) {
    this.list = []
    this.lastIndex = -1
    this.featureCallback = featureCallback
    this.finalCallback = finalCallback
    this.options = options

    if (!('sort' in this.options) || this.options.sort === false) {
      this.options.sort = null
    }
    if (!('sortDir' in this.options)) {
      this.options.sortDir = 'asc'
    }
    if (this.options.sort === true) {
      this.options.sort = 'index'
    }

    if (this.options.sort === 'BBoxDiagonalLength') {
      this.options.properties |= OverpassFrontend.BBOX
    }
  }

  next (err, feature, index) {
    if (typeof index === 'undefined') {
      index = this.list.length
    }

    this.list[index] = {
      err: err,
      feature: feature,
      index: index
    }

    if ((this.options.sort === null) ||
        (this.options.sort === 'index' && this.options.sortDir === 'asc' && index === this.lastIndex + 1)) {
      async.setImmediate(function () {
        this.featureCallback(this.list[index].err, this.list[index].feature, index)
      }.bind(this))

      this.lastIndex = index
    }
  }

  final (err) {
    if (this.options.sort === 'BBoxDiagonalLength') {
      for (let i = 0; i < this.list.length; i++) {
        const feature = this.list[i].feature

        if (feature && feature.bounds) {
          this.list[i].weight = feature.bounds.diagonalLength()
        }
      }

      this.list = weightSort(this.list)
    }

    if (this.options.sortDir === 'desc') {
      this.list.reverse()
    }

    async.setImmediate(function () {
      if (this.options.sort !== null) {
        for (let i = this.lastIndex + 1; i < this.list.length; i++) {
          // if a request got aborted, the entry in list is missing
          if (this.list[i]) {
            this.featureCallback(this.list[i].err, this.list[i].feature, i)
          }
        }
      }

      this.finalCallback(err)
    }.bind(this))
  }
}

module.exports = SortedCallbacks