kefir/src/many-sources/repeat.js

Reactive Programming library for JavaScript inspired by Bacon.js and RxJS with focus on high performance and low memory usage

import {inherit} from '../utils/objects'
import Stream from '../stream'
import {END} from '../constants'

function S(generator) {
  Stream.call(this)
  this._generator = generator
  this._source = null
  this._inLoop = false
  this._iteration = 0
  this._$handleAny = event => this._handleAny(event)
}

inherit(S, Stream, {
  _name: 'repeat',

  _handleAny(event) {
    if (event.type === END) {
      this._source = null
      this._getSource()
    } else {
      this._emit(event.type, event.value)
    }
  },

  _getSource() {
    if (!this._inLoop) {
      this._inLoop = true
      const generator = this._generator
      while (this._source === null && this._alive && this._active) {
        this._source = generator(this._iteration++)
        if (this._source) {
          this._source.onAny(this._$handleAny)
        } else {
          this._emitEnd()
        }
      }
      this._inLoop = false
    }
  },

  _onActivation() {
    if (this._source) {
      this._source.onAny(this._$handleAny)
    } else {
      this._getSource()
    }
  },

  _onDeactivation() {
    if (this._source) {
      this._source.offAny(this._$handleAny)
    }
  },

  _clear() {
    Stream.prototype._clear.call(this)
    this._generator = null
    this._source = null
    this._$handleAny = null
  },
})

export default function(generator) {
  return new S(generator)
}