kefir/src/one-source/values-to-errors.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}) {
    this._fn = fn
  },

  _free() {
    this._fn = null
  },

  _handleValue(x) {
    const fn = this._fn
    let result = fn(x)
    if (result.convert) {
      this._emitError(result.error)
    } else {
      this._emitValue(x)
    }
  },
}

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

const defFn = x => ({convert: true, error: x})

export default function valuesToErrors(obs, fn = defFn) {
  return new (obs._ofSameType(S, P))(obs, {fn})
}