Class MapRefImpl

repos/effect/packages/effect/src/unstable/reactivity/AtomRef.ts:194–227

}

class MapRefImpl<A, B> implements ReadonlyRef<B> {
  readonly [TypeId]: TypeId
  readonly key = keyState.generate()
  readonly parent: ReadonlyRef<A>
  readonly transform: (a: A) => B
  constructor(parent: ReadonlyRef<A>, transform: (a: A) => B) {
    this[TypeId] = TypeId
    this.parent = parent
    this.transform = transform
  }
  [Equal.symbol](that: Equal.Equal) {
    return Equal.equals(this.value, (that as ReadonlyRef<B>).value)
  }
  [Hash.symbol]() {
    return Hash.hash(this.value)
  }
  get value() {
    return this.transform(this.parent.value)
  }
  subscribe(f: (a: B) => void): () => void {
    let previous = this.transform(this.parent.value)
    return this.parent.subscribe((a) => {
      const next = this.transform(a)
      if (Equal.equals(next, previous)) {
        return
      }
      previous = next
      f(next)
    })
  }
  map<C>(f: (a: B) => C): ReadonlyRef<C> {
    return new MapRefImpl(this, f)
  }
}

class PropRefImpl<A, K extends keyof A> implements AtomRef<A[K]> {
  readonly [TypeId]: TypeId