@zkochan/pnpm/lib/node_modules/most/src/fusion/Map.js

Fast, disk space efficient package manager

/** @license MIT License (c) copyright 2010-2016 original author or authors */
/** @author Brian Cavalier */
/** @author John Hann */

import Pipe from '../sink/Pipe'
import Filter from './Filter'
import FilterMap from './FilterMap'
import * as base from '@most/prelude'

export default function Map (f, source) {
  this.f = f
  this.source = source
}

/**
 * Create a mapped source, fusing adjacent map.map, filter.map,
 * and filter.map.map if possible
 * @param {function(*):*} f mapping function
 * @param {{run:function}} source source to map
 * @returns {Map|FilterMap} mapped source, possibly fused
 */
Map.create = function createMap (f, source) {
  if (source instanceof Map) {
    return new Map(base.compose(f, source.f), source.source)
  }

  if (source instanceof Filter) {
    return new FilterMap(source.p, f, source.source)
  }

  return new Map(f, source)
}

Map.prototype.run = function (sink, scheduler) { // eslint-disable-line no-extend-native
  return this.source.run(new MapSink(this.f, sink), scheduler)
}

function MapSink (f, sink) {
  this.f = f
  this.sink = sink
}

MapSink.prototype.end = Pipe.prototype.end
MapSink.prototype.error = Pipe.prototype.error

MapSink.prototype.event = function (t, x) {
  var f = this.f
  this.sink.event(t, f(x))
}