README
Compose Iterator
Use iterator for middleware composition.
Installation
$ npm install compose-iterator
Examples
compose.js
'use strict'
const Promise = require('any-promise')
const iterator = require('..')
/**
* 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) {
// iteration object
const iter = iterator[Symbol.iterator](middleware, context, next)
try {
return Promise.resolve(iter.next().value)
} catch (err) {
return Promise.reject(err)
}
}
}
app.js
const co = require('co')
const compose = require('./compose')
function wait (ms) {
return new Promise((resolve) => setTimeout(resolve, ms || 1))
}
var arr = []
var stack = []
stack.push(function * (context, next) {
arr.push(1)
yield wait(1)
yield next()
yield wait(1)
arr.push(6)
})
stack.push(function * (context, next) {
arr.push(2)
yield wait(1)
yield next()
yield wait(1)
arr.push(5)
})
stack.push(function * (context, next) {
arr.push(3)
yield wait(1)
yield next()
yield wait(1)
arr.push(4)
})
compose(stack.map((fn) => co.wrap(fn)))({}).then(function () {
console.log(arr.toString() === [1, 2, 3, 4, 5, 6].toString())
})
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