Class BoundedPubSubSingleSubscription

packages/effect/src/internal/pubsub.ts:663–721

@internal

/** @internal */
class BoundedPubSubSingleSubscription<in out A> implements Subscription<A> {
  constructor(
    private self: BoundedPubSubSingle<A>,
    private subscriberIndex: number,
    private unsubscribed: boolean
  ) {
  }

  isEmpty(): boolean {
    return (
      this.unsubscribed ||
      this.self.subscribers === 0 ||
      this.subscriberIndex === this.self.publisherIndex
    )
  }

  size() {
    return this.isEmpty() ? 0 : 1
  }

  poll<D>(default_: D): A | D {
    if (this.isEmpty()) {
      return default_
    }
    const elem = this.self.value
    this.self.subscribers -= 1
    if (this.self.subscribers === 0) {
      this.self.value = AbsentValue as unknown as A
    }
    this.subscriberIndex += 1
    return elem
  }

  pollUpTo(n: number): Chunk.Chunk<A> {
    if (this.isEmpty() || n < 1) {
      return Chunk.empty()
    }
    const a = this.self.value
    this.self.subscribers -= 1
    if (this.self.subscribers === 0) {
      this.self.value = AbsentValue as unknown as A
    }
    this.subscriberIndex += 1
    return Chunk.of(a)
  }

  unsubscribe(): void {
    if (!this.unsubscribed) {
      this.unsubscribed = true
      this.self.subscriberCount -= 1
      if (this.subscriberIndex !== this.self.publisherIndex) {
        this.self.subscribers -= 1
        if (this.self.subscribers === 0) {
          this.self.value = AbsentValue as unknown as A
        }
      }
    }
  }