carbon-components-svelte/types/DataTable/DataTableTypes.d.ts

type PathDepth = [never, 0, 1, 2, ...0[]];

type Join<K, P> = K extends string | number
  ? P extends string | number
  ? `${K}${"" extends P ? "" : "."}${P}`
  : never
  : never;

// For performance, the maximum traversal depth is 10.
export type PropertyPath<T, D extends number = 10> = [D] extends [never]
  ? never
  : T extends object
  ? {
    [K in keyof T]-?: K extends string | number
    ? `${K}` | Join<K, PropertyPath<T[K], PathDepth[D]>>
    : never;
  }[keyof T]
  : "";