Method move

packages/db-ivm/src/operators/topKArray.ts:101–152

* Moves the topK window

({
    offset,
    limit,
  }: {
    offset?: number
    limit?: number
  })

   * Moves the topK window
   */
  move({
    offset,
    limit,
  }: {
    offset?: number
    limit?: number
  }): TopKMoveChanges<V> {
    const oldOffset = this.#topKStart
    const oldLimit = this.#topKEnd - this.#topKStart

    // `this.#topKEnd` can be `Infinity` if it has no limit
    // but `diffHalfOpen` expects a finite range
    // so we restrict it to the size of the topK if topKEnd is infinite
    const oldRange: HRange = [
      this.#topKStart,
      this.#topKEnd === Infinity ? this.#topKStart + this.size : this.#topKEnd,
    ]

    this.#topKStart = offset ?? oldOffset
    this.#topKEnd = this.#topKStart + (limit ?? oldLimit) // can be `Infinity` if limit is `Infinity`

    // Also handle `Infinity` in the newRange
    const newRange: HRange = [
      this.#topKStart,
      this.#topKEnd === Infinity
        ? Math.max(this.#topKStart + this.size, oldRange[1]) // since the new limit is Infinity we need to take everything (so we need to take the biggest (finite) topKEnd)
        : this.#topKEnd,
    ]
    const { onlyInA, onlyInB } = diffHalfOpen(oldRange, newRange)

    const moveIns: Array<IndexedValue<V>> = []
    onlyInB.forEach((index) => {
      const value = this.#sortedValues[index]
      if (value) {
        moveIns.push(value)
      }
    })

    const moveOuts: Array<IndexedValue<V>> = []
    onlyInA.forEach((index) => {
      const value = this.#sortedValues[index]
      if (value) {
        moveOuts.push(value)
      }
    })

    // It could be that there are changes (i.e. moveIns or moveOuts)
    // but that the collection is lazy so we don't have the data yet that needs to move in/out
    // so `moveIns` and `moveOuts` will be empty but `changes` will be true
    // this will tell the caller that it needs to run the graph to load more data
    return { moveIns, moveOuts, changes: onlyInA.length + onlyInB.length > 0 }
  }

  insert(value: V): TopKChanges<V> {
    const result: TopKChanges<V> = { moveIn: null, moveOut: null }