kefir/src/one-source/buffer-while.js

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

import {createStream, createProperty} from '../patterns/one-source'

const mixin = {
  _init({fn, flushOnEnd}) {
    this._fn = fn
    this._flushOnEnd = flushOnEnd
    this._buff = []
  },

  _free() {
    this._buff = null
  },

  _flush() {
    if (this._buff !== null && this._buff.length !== 0) {
      this._emitValue(this._buff)
      this._buff = []
    }
  },

  _handleValue(x) {
    this._buff.push(x)
    const fn = this._fn
    if (!fn(x)) {
      this._flush()
    }
  },

  _handleEnd() {
    if (this._flushOnEnd) {
      this._flush()
    }
    this._emitEnd()
  },
}

const S = createStream('bufferWhile', mixin)
const P = createProperty('bufferWhile', mixin)

const id = x => x

export default function bufferWhile(obs, fn, {flushOnEnd = true} = {}) {
  return new (obs._ofSameType(S, P))(obs, {fn: fn || id, flushOnEnd})
}