Line data    Source code

       1             : import { Engine } from "../types.ts";
       2           1 : import { integer } from "./integer.ts";
       3             : 
       4             : /**
       5             :  * Shuffles an array in-place
       6             :  * @param engine The Engine to use when choosing random values
       7             :  * @param array The array to shuffle
       8             :  * @param downTo minimum index to shuffle. Only used internally.
       9             :  */
      10           0 : export function shuffle<T>(
      11           0 :   engine: Engine,
      12           0 :   array: T[],
      13           0 :   downTo: number = 0
      14             : ): T[] {
      15           0 :   const length = array.length;
      16           0 :   if (length) {
      17           0 :     for (let i = (length - 1) >>> 0; i > downTo; --i) {
      18           0 :       const distribution = integer(0, i);
      19           0 :       const j = distribution(engine);
      20           0 :       if (i !== j) {
      21           0 :         const tmp = array[i];
      22           0 :         array[i] = array[j];
      23           0 :         array[j] = tmp;
      24           0 :       }
      25           0 :     }
      26           0 :   }
      27           0 :   return array;
      28           0 : }