lodash/lodash.flow/index.js

/**
 * lodash 3.0.2 (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 1.7.0 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var arrayEvery = require('lodash._arrayevery');

/** Used as the `TypeError` message for "Functions" methods. */
var FUNC_ERROR_TEXT = 'Expected a function';

/**
 * The base implementation of `_.isFunction` without support for environments
 * with incorrect `typeof` results.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
 */
function baseIsFunction(value) {
  // Avoid a Chakra JIT bug in compatibility modes of IE 11.
  // See https://github.com/jashkenas/underscore/issues/1621 for more details.
  return typeof value == 'function' || false;
}

/**
 * Creates a function that returns the result of invoking the provided
 * functions with the `this` binding of the created function, where each
 * successive invocation is supplied the return value of the previous.
 *
 * @static
 * @memberOf _
 * @category Function
 * @param {...Function} [funcs] Functions to invoke.
 * @returns {Function} Returns the new function.
 * @example
 *
 * function square(n) {
 *   return n * n;
 * }
 *
 * var addSquare = _.flow(_.add, square);
 * addSquare(1, 2);
 * // => 9
 */
function flow() {
  var funcs = arguments,
      length = funcs.length;

  if (!length) {
    return function() { return arguments[0]; };
  }
  if (!arrayEvery(funcs, baseIsFunction)) {
    throw new TypeError(FUNC_ERROR_TEXT);
  }
  return function() {
    var index = 0,
        result = funcs[index].apply(this, arguments);

    while (++index < length) {
      result = funcs[index].call(this, result);
    }
    return result;
  };
}

module.exports = flow;