Method takeInternal

packages/db/src/indexes/btree-index.ts:301–333

* Internal method for taking items from the index. * @param n - The number of items to return * @param nextPair - Function to get the next pair from the BTree * @param from - Already normalized! undefined means "start from beginning/end", sentinel means "start from the key undefined" * @

(
    n: number,
    nextPair: (k?: any) => [any, any] | undefined,
    from: any,
    filterFn?: (key: TKey) => boolean,
    reversed: boolean = false,
  )

   * @param reversed - Whether to reverse the order of keys within each value
   */
  private takeInternal(
    n: number,
    nextPair: (k?: any) => [any, any] | undefined,
    from: any,
    filterFn?: (key: TKey) => boolean,
    reversed: boolean = false,
  ): Array<TKey> {
    const keysInResult: Set<TKey> = new Set()
    const result: Array<TKey> = []
    let pair: [any, any] | undefined
    let key = from // Use as-is - it's already normalized by the caller

    while ((pair = nextPair(key)) !== undefined && result.length < n) {
      key = pair[0]
      const keys = this.valueMap.get(key) as
        | Set<Exclude<TKey, undefined>>
        | undefined
      if (keys && keys.size > 0) {
        // Sort keys for deterministic order, reverse if needed
        const sorted = Array.from(keys).sort(compareKeys)
        if (reversed) sorted.reverse()
        for (const ks of sorted) {
          if (result.length >= n) break
          if (!keysInResult.has(ks) && (filterFn?.(ks) ?? true)) {
            result.push(ks)
            keysInResult.add(ks)
          }
        }
      }
    }

    return result
  }

  /**
   * Returns the next n items after the provided item.