lodash/lodash.bind/index.js

/**
 * lodash 3.0.0 (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 baseSlice = require('lodash._baseslice'),
    createWrapper = require('lodash._createwrapper'),
    replaceHolders = require('lodash._replaceholders');

/** Used to compose bitmasks for wrapper metadata. */
var BIND_FLAG = 1,
    PARTIAL_FLAG = 32;

/**
 * Creates a function that invokes `func` with the `this` binding of `thisArg`
 * and prepends any additional `_.bind` arguments to those provided to the
 * bound function.
 *
 * The `_.bind.placeholder` value, which defaults to `_` in monolithic builds,
 * may be used as a placeholder for partially applied arguments.
 *
 * **Note:** Unlike native `Function#bind` this method does not set the `length`
 * property of bound functions.
 *
 * @static
 * @memberOf _
 * @category Function
 * @param {Function} func The function to bind.
 * @param {*} thisArg The `this` binding of `func`.
 * @param {...*} [args] The arguments to be partially applied.
 * @returns {Function} Returns the new bound function.
 * @example
 *
 * var greet = function(greeting, punctuation) {
 *   return greeting + ' ' + this.user + punctuation;
 * };
 *
 * var object = { 'user': 'fred' };
 *
 * var bound = _.bind(greet, object, 'hi');
 * bound('!');
 * // => 'hi fred!'
 *
 * // using placeholders
 * var bound = _.bind(greet, object, _, '!');
 * bound('hi');
 * // => 'hi fred!'
 */
function bind(func, thisArg) {
  var bitmask = BIND_FLAG;
  if (arguments.length > 2) {
    var partials = baseSlice(arguments, 2),
        holders = replaceHolders(partials, bind.placeholder);

    bitmask |= PARTIAL_FLAG;
  }
  return createWrapper(func, bitmask, thisArg, partials, holders);
}

// Assign default placeholders.
bind.placeholder = {};

module.exports = bind;