/**
 * Return an array with the numbers from 0 to n-1, in a random order
 */
function getRandomArray (n) {
  var res, next;

  if (n === 0) { return []; }
  if (n === 1) { return [0]; }

  res = getRandomArray(n - 1);
  next = Math.floor(Math.random() * n);
  res.splice(next, 0, n - 1);   // Add n-1 at a random position in the array

  return res;
};
module.exports.getRandomArray = getRandomArray;


/*
 * Default compareKeys function will work for numbers, strings and dates
 */
function defaultCompareKeysFunction (a, b) {
  if (a < b) { return -1; }
  if (a > b) { return 1; }
  if (a === b) { return 0; }

  var err = new Error("Couldn't compare elements");
  err.a = a;
  err.b = b;
  throw err;
}
module.exports.defaultCompareKeysFunction = defaultCompareKeysFunction;


/**
 * Check whether two values are equal (used in non-unique deletion)
 */
function defaultCheckValueEquality (a, b) {
  return a === b;
}
module.exports.defaultCheckValueEquality = defaultCheckValueEquality;