Class KeySetImpl

packages/effect/src/internal/cache.ts:167–209

}

class KeySetImpl<in out K> implements KeySet<K> {
  head: MapKey<K> | undefined = undefined
  tail: MapKey<K> | undefined = undefined
  add(key: MapKey<K>): void {
    if (key !== this.tail) {
      if (this.tail === undefined) {
        this.head = key
        this.tail = key
      } else {
        const previous = key.previous
        const next = key.next
        if (next !== undefined) {
          key.next = undefined
          if (previous !== undefined) {
            previous.next = next
            next.previous = previous
          } else {
            this.head = next
            this.head.previous = undefined
          }
        }
        this.tail.next = key
        key.previous = this.tail
        this.tail = key
      }
    }
  }
  remove(): MapKey<K> | undefined {
    const key = this.head
    if (key !== undefined) {
      const next = key.next
      if (next !== undefined) {
        key.next = undefined
        this.head = next
        this.head.previous = undefined
      } else {
        this.head = undefined
        this.tail = undefined
      }
    }
    return key
  }
}

/** @internal */
export const makeKeySet = <K>(): KeySet<K> => new KeySetImpl<K>()