Adapter layer for bridging `handlebars-layouts` and `express-handlebars`.

handlebars_layouts_express_handlebars_adapter.js

/**
 * Adapter layer for bridging `handlebars-layouts` and `express-handlebars`.
 *
 * Usage:
 *    var exphbs  = require('express-handlebars');
 *    var handlebarsLayout = require('handlebars-layouts');
 *    var exphbsAdapter = require('express-handlebars-layouts-adapter');
 *
 *    handlebarsLayout(exphbsAdapter);
 *    var exphbs.create({
 *        helpers: handlebarsLayout(exphbsAdapter()).helpers()
 *    });
 *    app.engine('handlebars', hbs.engine);
 *
 * WUT?
 *
 * It is not easy to use `handlebars-layouts` with `express-handlebars`.
 *
 * handlebars-layouts API
 *
 *     layouts(handlebars); // calls handlebars.registerHelper(helpers);
 *                          // then returns handlebars
 *
 * express-handlebars API
 *     var express = require('express'),
 *     exphbs  = require('express-handlebars');
 *
 *     var app = express();
 *
 *     var hbs = exphbs.create({
 *           // Specify helpers which are only registered on this instance.
 *          helpers: {
 *               foo: function () { return 'FOO!'; },
 *               bar: function () { return 'BAR!'; }
 *           }
 *     });
 *
 *     app.engine('handlebars', hbs.engine);
 *     app.set('view engine', 'handlebars');
 */
module.exports = function() {
  var _helpers = {};
  return {
    registerHelper: function registerHelper(helpers) {
      _helpers = helpers;
    },
    helpers: function() {
      return _helpers;
    }
  };
 };