In-Place Array Permutation Tracking with TypedArrays in React Virtual Grid Renderers

import React, { useRef, useCallback } from 'react';
 
export function useArrayPermutationIndex(itemCount) {
  const indexMapRef = useRef(null);
 
  if (indexMapRef.current === null || indexMapRef.current.length !== itemCount) {
    const buffer = new Int32Array(itemCount);
    for (let i = 0; i < itemCount; i++) {
      buffer[i] = i;
    }
    indexMapRef.current = buffer;
  }
 
  const swapIndices = useCallback((fromIndex, toIndex) => {
    const buffer = indexMapRef.current;
    if (
      fromIndex < 0 || fromIndex >= buffer.length ||
      toIndex < 0 || toIndex >= buffer.length
    ) {
      throw new RangeError('Permutation index out of bounds');
    }
    const temp = buffer[fromIndex];
    buffer[fromIndex] = buffer[toIndex];
    buffer[toIndex] = temp;
  }, []);
 
  return { indexMap: indexMapRef.current, swapIndices };
}