githubmirror/lodash

_baseRepeat.js

38 строк1 KB

John-David Dalton

Bump to v4.7.0.

31 мар 2016, 10:33

31 мар 2016, 10:33d46bcaa

define([], function() {

  /** Used as references for various `Number` constants. */
  var MAX_SAFE_INTEGER = 9007199254740991;

  /* Built-in method references for those with the same name as other `lodash` methods. */
  var nativeFloor = Math.floor;

  /**
   * The base implementation of `_.repeat` which doesn't coerce arguments.
   *
   * @private
   * @param {string} string The string to repeat.
   * @param {number} n The number of times to repeat the string.
   * @returns {string} Returns the repeated string.
   */
  function baseRepeat(string, n) {
    var result = '';
    if (!string || n < 1 || n > MAX_SAFE_INTEGER) {
      return result;
    }
    // Leverage the exponentiation by squaring algorithm for a faster repeat.
    // See https://en.wikipedia.org/wiki/Exponentiation_by_squaring for more details.
    do {
      if (n % 2) {
        result += string;
      }
      n = nativeFloor(n / 2);
      if (n) {
        string += string;
      }
    } while (n);

    return result;
  }

  return baseRepeat;
});