spirit/lib/core/core.js

extensible web library for building applications & frameworks

"use strict";

/*
 * main spirit file
 */

var p_utils = require("./promise_utils");

/**
 * A reducer function, for reducing over a handler
 * and middlewares
 *
 * All functions are expected to return a Promise
 * It is wrapped to ensure a Promise is returned
 *
 * @param {function} handler - a handler function
 * @param {array} middleware - an array of middleware function
 * @return {function} returns a function that takes a input and returns a output as a (promise)
 */
var compose = function compose(handler, middleware) {
  // wrap `fn` to always returns a promise
  var wrap = function wrap(fn) {
    return function () {
      return p_utils.callp(fn, arguments);
    };
  };

  var accum = wrap(handler);

  for (var i = middleware.length - 1; i >= 0; i--) {
    accum = wrap(middleware[i](accum));
  }

  return accum;
};

module.exports = {
  compose: compose
};