use strict
/**
* Expose compositor.
*/
module.exports = compose
/**
* Compose `middleware` returning
* a fully valid middleware comprised
* of all those which are passed.
*
* @param Array middleware
* @return Function
* @api public
*/
function compose (middleware)
if (!Array.isArray(middleware)) throw new TypeError(Middleware stack must be an array!)
for (const fn of middleware)
if (typeof fn !== function) throw new TypeError(Middleware must be composed of functions!)
/**
* @param Object context
* @return Promise
* @api public
*/
return function (context, next)
// last called middleware #
let index = -1
return dispatch(0)
function dispatch (i)
if (i <= index) return Promise.reject(new Error(next() called multiple times))
index = i
let fn = middleware[i]
if (i === middleware.length) fn = next
if (!fn) return Promise.resolve()
try
return Promise.resolve(fn(context, dispatch.bind(null, i + 1)))
catch (err)
return Promise.reject(err)
function compose (middleware) {
if (!Array.isArray(middleware)) thrownew TypeError(‘Middleware stack must be an array!‘)
for (const fn of middleware) {
if (typeof fn !== ‘function‘) thrownew TypeError(‘Middleware must be composed of functions!‘)
}
/**
* @param {Object} context
* @return {Promise}
* @api public
*/returnfunction (context, next) {
// last called middleware #
let index = -1
return dispatch(0)
function dispatch (i) {
if (i <= index) return Promise.reject(new Error(‘next() called multiple times‘))
index = i
let fn = middleware[i]
if (i === middleware.length) fn = next
if (!fn) return Promise.resolve()
try {
return Promise.resolve(fn(context, function next () {
return dispatch(i + 1)
}))
} catch (err) {
return Promise.reject(err)
}
}
}
}