lens/packages/utility-features/utilities/src/array.ts

/**
 * Copyright (c) OpenLens Authors. All rights reserved.
 * Licensed under MIT License. See LICENSE in root directory for more information.
 */

/**
 * A inference typed version of `Array(length).fill(value)`
 * @param length The number of entries
 * @param value The value of each of the indices
 */
function filled<T>(length: number, value: T): T[] {
  return Array(length).fill(value);
}

/**
 * This function splits an array into two sub arrays on the first instance of
 * element (from the left). If the array does not contain the element. The
 * return value is defined to be `[array, [], false]`. If the element is in
 * the array then the return value is `[left, right, true]` where `left` is
 * the elements of `array` from `[0, index)` and `right` is `(index, length)`
 * @param array the full array to split into two sub-arrays
 * @param element the element in the middle of the array
 * @returns the left and right sub-arrays which when conjoined with `element`
 *          is the same as `array`, and `true`
 */
function split<T>(src: T[], element: T): [T[], T[], boolean] {
  const index = src.indexOf(element);

  if (index < 0) {
    return [src, [], false];
  }

  return [src.slice(0, index), src.slice(index + 1, src.length), true];
}

function bifurcate<T>(src: T[], condition: (item: T) => any): [falses: T[], trues: T[]] {
  const trues: T[] = [];
  const falses: T[] = [];

  for (const item of src) {
    if (condition(item)) {
      trues.push(item);
    } else {
      falses.push(item);
    }
  }

  return [falses, trues];
}

export const array = {
  bifurcate,
  filled,
  split,
};