uniq.js

var baseCallback = require('../internal/baseCallback'),
    baseUniq = require('../internal/baseUniq'),
    isIterateeCall = require('../internal/isIterateeCall'),
    sortedUniq = require('../internal/sortedUniq');

/**
 * Creates a duplicate-free version of an array, using
 * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
 * for equality comparisons, in which only the first occurence of each element
 * is kept. Providing `true` for `isSorted` performs a faster search algorithm
 * for sorted arrays. If an iteratee function is provided it is invoked for
 * each element in the array to generate the criterion by which uniqueness
 * is computed. The `iteratee` is bound to `thisArg` and invoked with three
 * arguments: (value, index, array).
 *
 * If a property name is provided for `iteratee` the created `_.property`
 * style callback returns the property value of the given element.
 *
 * If a value is also provided for `thisArg` the created `_.matchesProperty`
 * style callback returns `true` for elements that have a matching property
 * value, else `false`.
 *
 * If an object is provided for `iteratee` the created `_.matches` style
 * callback returns `true` for elements that have the properties of the given
 * object, else `false`.
 *
 * @static
 * @memberOf _
 * @alias unique
 * @category Array
 * @param {Array} array The array to inspect.
 * @param {boolean} [isSorted] Specify the array is sorted.
 * @param {Function|Object|string} [iteratee] The function invoked per iteration.
 * @param {*} [thisArg] The `this` binding of `iteratee`.
 * @returns {Array} Returns the new duplicate-value-free array.
 * @example
 *
 * _.uniq([2, 1, 2]);
 * // => [2, 1]
 *
 * // using `isSorted`
 * _.uniq([1, 1, 2], true);
 * // => [1, 2]
 *
 * // using an iteratee function
 * _.uniq([1, 2.5, 1.5, 2], function(n) {
 *   return this.floor(n);
 * }, Math);
 * // => [1, 2.5]
 *
 * // using the `_.property` callback shorthand
 * _.uniq([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
 * // => [{ 'x': 1 }, { 'x': 2 }]
 */
function uniq(array, isSorted, iteratee, thisArg) {
  var length = array ? array.length : 0;
  if (!length) {
    return [];
  }
  if (isSorted != null && typeof isSorted != 'boolean') {
    thisArg = iteratee;
    iteratee = isIterateeCall(array, isSorted, thisArg) ? null : isSorted;
    isSorted = false;
  }
  iteratee = iteratee == null ? iteratee : baseCallback(iteratee, thisArg, 3);
  return (isSorted)
    ? sortedUniq(array, iteratee)
    : baseUniq(array, iteratee);
}

module.exports = uniq;