immutable-map-subtract.js

/* eslint new-cap: 0 */

import { Iterable } from 'immutable'

/**
 * Subtracts a set of Maps from the current Map.
 */
export default function mapSubtract(targetMap, ...iterators) {
  if (iters.length === 0) {
    return targetMap
  }

  const iterableHasKeyFilter = key => iterable => {
    return Iterable.isKeyed(iterable) ? iterable.has(key) : iterable.includes(key)
  }

  const iters = iterators.map(iter => Iterable(iter))
  return targetMap.withMutations(map => {
    const iterator = targetMap.keys()
    let step = iterator.next()
    let key

    while (!step.done) {
      key = step.value
      const hasKey = iters.some(iterableHasKeyFilter(key))

      if (hasKey) {
        map.delete(key)
      }

      step = iterator.next()
    }
  })
}