lodash/_lazyValue.js

var baseWrapperValue = require('./_baseWrapperValue'),
    getView = require('./_getView'),
    isArray = require('./isArray');

/** Used as the size to enable large array optimizations. */
var LARGE_ARRAY_SIZE = 200;

/** Used to indicate the type of lazy iteratees. */
var LAZY_FILTER_FLAG = 1,
    LAZY_MAP_FLAG = 2;

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

/**
 * Extracts the unwrapped value from its lazy wrapper.
 *
 * @private
 * @name value
 * @memberOf LazyWrapper
 * @returns {*} Returns the unwrapped value.
 */
function lazyValue() {
  var array = this.__wrapped__.value(),
      dir = this.__dir__,
      isArr = isArray(array),
      isRight = dir < 0,
      arrLength = isArr ? array.length : 0,
      view = getView(0, arrLength, this.__views__),
      start = view.start,
      end = view.end,
      length = end - start,
      index = isRight ? end : (start - 1),
      iteratees = this.__iteratees__,
      iterLength = iteratees.length,
      resIndex = 0,
      takeCount = nativeMin(length, this.__takeCount__);

  if (!isArr || arrLength < LARGE_ARRAY_SIZE ||
      (arrLength == length && takeCount == length)) {
    return baseWrapperValue(array, this.__actions__);
  }
  var result = [];

  outer:
  while (length-- && resIndex < takeCount) {
    index += dir;

    var iterIndex = -1,
        value = array[index];

    while (++iterIndex < iterLength) {
      var data = iteratees[iterIndex],
          iteratee = data.iteratee,
          type = data.type,
          computed = iteratee(value);

      if (type == LAZY_MAP_FLAG) {
        value = computed;
      } else if (!computed) {
        if (type == LAZY_FILTER_FLAG) {
          continue outer;
        } else {
          break outer;
        }
      }
    }
    result[resIndex++] = value;
  }
  return result;
}

module.exports = lazyValue;