lodash/lodash._baseflatten/index.js

/**
 * lodash 3.1.3 (Custom Build) <https://lodash.com/>
 * Build: `lodash modern modularize exports="npm" -o ./`
 * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var isArguments = require('lodash.isarguments'),
    isArray = require('lodash.isarray');

/**
 * Checks if `value` is object-like.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is object-like, else `false`.
 */
function isObjectLike(value) {
  return !!value && typeof value == 'object';
}

/**
 * Used as the [maximum length](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-number.max_safe_integer)
 * of an array-like value.
 */
var MAX_SAFE_INTEGER = 9007199254740991;

/**
 * The base implementation of `_.flatten` with added support for restricting
 * flattening and specifying the start index.
 *
 * @private
 * @param {Array} array The array to flatten.
 * @param {boolean} [isDeep] Specify a deep flatten.
 * @param {boolean} [isStrict] Restrict flattening to arrays-like objects.
 * @returns {Array} Returns the new flattened array.
 */
function baseFlatten(array, isDeep, isStrict) {
  var index = -1,
      length = array.length,
      resIndex = -1,
      result = [];

  while (++index < length) {
    var value = array[index];
    if (isObjectLike(value) && isArrayLike(value) &&
        (isStrict || isArray(value) || isArguments(value))) {
      if (isDeep) {
        // Recursively flatten arrays (susceptible to call stack limits).
        value = baseFlatten(value, isDeep, isStrict);
      }
      var valIndex = -1,
          valLength = value.length;

      while (++valIndex < valLength) {
        result[++resIndex] = value[valIndex];
      }
    } else if (!isStrict) {
      result[++resIndex] = value;
    }
  }
  return result;
}

/**
 * The base implementation of `_.property` without support for deep paths.
 *
 * @private
 * @param {string} key The key of the property to get.
 * @returns {Function} Returns the new function.
 */
function baseProperty(key) {
  return function(object) {
    return object == null ? undefined : object[key];
  };
}

/**
 * Gets the "length" property value of `object`.
 *
 * **Note:** This function is used to avoid a [JIT bug](https://bugs.webkit.org/show_bug.cgi?id=142792)
 * that affects Safari on at least iOS 8.1-8.3 ARM64.
 *
 * @private
 * @param {Object} object The object to query.
 * @returns {*} Returns the "length" value.
 */
var getLength = baseProperty('length');

/**
 * Checks if `value` is array-like.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is array-like, else `false`.
 */
function isArrayLike(value) {
  return value != null && isLength(getLength(value));
}

/**
 * Checks if `value` is a valid array-like length.
 *
 * **Note:** This function is based on [`ToLength`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength).
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a valid length, else `false`.
 */
function isLength(value) {
  return typeof value == 'number' && value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER;
}

module.exports = baseFlatten;