CHOMPStation2/tgui/packages/common/collections.ts

/**
 * @file
 * @copyright 2020 Aleksej Komarov
 * @license MIT
 */

const binarySearch = <T, U = unknown>(
  getKey: (value: T) => U,
  collection: readonly T[],
  inserting: T,
): number => {
  if (collection.length === 0) {
    return 0;
  }

  const insertingKey = getKey(inserting);

  let [low, high] = [0, collection.length];

  // Because we have checked if the collection is empty, it's impossible
  // for this to be used before assignment.
  let compare: U = undefined as unknown as U;
  let middle = 0;

  while (low < high) {
    middle = (low + high) >> 1;

    compare = getKey(collection[middle]);

    if (compare < insertingKey) {
      low = middle + 1;
    } else if (compare === insertingKey) {
      return middle;
    } else {
      high = middle;
    }
  }

  return compare > insertingKey ? middle : middle + 1;
};

export const binaryInsertWith = <T, U = unknown>(
  collection: readonly T[],
  value: T,
  getKey: (value: T) => U,
): T[] => {
  const copy = [...collection];
  copy.splice(binarySearch(getKey, collection, value), 0, value);
  return copy;
};