export function mapValues<T, R> (o: { [key: string]: T }, mapper: (v: T) => R): { [key: string]: R } {
  let result: { [key: string]: R } = {}

  for (const key in o) {
    if (o.hasOwnProperty(key)) {
      const v = o[key]
      result[key] = mapper(v)
    }
  }

  return result
}

/**
 * Overwrite values or properties on objects and lists recursively.
 * A shallow copy will be created for each array value.
 */
export function assignDeep<T> (target: Partial<T>, ...sources: (Partial<T> | undefined)[]): T {
  sources.forEach(s => {
    if (!s) return
    for (const key in s) {
      if (s.hasOwnProperty(key)) {
        const v = s[key] as any
        if (Array.isArray(v)) {
          // Shallow copy
          target[key] = v.slice(0) as any
        } else if (typeof v === 'object') {
          if (!target[key]) target[key] = {} as any
          assignDeep<any>(target[key] as any, v)
        } else {
          target[key] = v
        }
      }
    }
  })
  return target as T
}