_utils.ts

// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.

/**
 * Filters the given array, removing all elements that do not match the given predicate
 * **in place. This means `array` will be modified!**.
 */
export function filterInPlace<T>(
  array: Array<T>,
  predicate: (el: T) => boolean,
): Array<T> {
  let outputIndex = 0;

  for (const cur of array) {
    if (!predicate(cur)) {
      continue;
    }

    array[outputIndex] = cur;
    outputIndex += 1;
  }

  array.splice(outputIndex);

  return array;
}

/**
 * Produces a random number between the inclusive `lower` and `upper` bounds.
 */
export function randomInteger(lower: number, upper: number) {
  return lower + Math.floor(Math.random() * (upper - lower + 1));
}