zent/src/utils/reorder.ts

一套前端设计语言和基于React的实现

/*
 * Utility to reorder list
 * Scans the list only once.
 */
export default function reorder<T>(
  array: T[],
  fromIndex: number,
  toIndex: number
) {
  const lastIndex = array.length - 1;
  const firstIndex = 0;
  const result = new Array(array.length);
  let tmp: T;

  if (fromIndex === toIndex) {
    return array;
  }

  if (fromIndex < toIndex) {
    for (let i = firstIndex; i <= lastIndex; i++) {
      if (i === fromIndex) {
        tmp = array[i];
      } else if (i > fromIndex && i < toIndex) {
        result[i - 1] = array[i];
      } else if (i === toIndex) {
        result[i - 1] = array[i];
        result[i] = tmp;
      } else {
        result[i] = array[i];
      }
    }
  } else {
    for (let i = lastIndex; i >= firstIndex; i--) {
      if (i === fromIndex) {
        tmp = array[i];
      } else if (i < fromIndex && i > toIndex) {
        result[i + 1] = array[i];
      } else if (i === toIndex) {
        result[i] = tmp;
        result[i + 1] = array[i];
      } else {
        result[i] = array[i];
      }
    }
  }

  return result;
}