动态扩展Node.js中的管道链条

Question

我目前正在使用模块through2,concat-stream和request在Node.js中使用流实践。

我设置了管链是这样的：

request(process.argv[2]) 
.pipe(through(write, end)) 
.pipe(/*And */) 
.pipe(/* Some */) 
.pipe(/* more */) 
.on("finish",function(){ #Do some stuff }); 

function write(buf, enc, nxt){ 
    /*Push some data after some processing*/ 
} 
function end(done){ 
    done() 
} 

这是管的静止链。是否可以通过某种形式的用户输入动态指定管道链？

在伪代码：

array_of_user_pipes = from_some_input; 
pipe_library = {pipe_name:pipe_callback} object, loaded into application logic 

perform the url request (fetch .txt file over the internet) 
for all pipe in array_of_user_pipes do 
    fetch pipe from pipe_library (simple key look-up) 
    chain pipe to chain 
execute the (dynamic) pipe chain 

Answer 1

在把你的伪代码没有问题的js

const pipesMap = { 
    pipeName1: require('pipe-module'), 
    pipeName2: function(){}, 
    ... 
} 

定义piper功能，通过每个需要管道名称，并返回一个函数，管道初始事件流其中。

const piper = pipes => request => 
     pipes.reduce((piped, pipe) => piped.pipe(pipesMap[pipe]), request) 


const userInputPipesArray = ['pipeName1', 'pipeName2'] 

piper(userInputPipesArray)(request(process.argv[2])).on('finish') 

编辑

你可以使用环

let piped = request(process.argv[2]) 

for(let pipe of userInputPipesArray) { 
    piped = piped.pipe(pipeMap[pipe]) 
} 

piped.on('finish', ...)