306 lines
6.9 KiB
JavaScript
306 lines
6.9 KiB
JavaScript
//filter will reemit the data if cb(err,pass) pass is truthy
|
|
|
|
// reduce is more tricky
|
|
// maybe we want to group the reductions or emit progress updates occasionally
|
|
// the most basic reduce just emits one 'data' event after it has recieved 'end'
|
|
|
|
var Stream = require('stream').Stream
|
|
, es = exports
|
|
, through = require('through')
|
|
, from = require('from')
|
|
, duplex = require('duplexer')
|
|
, map = require('map-stream')
|
|
, pause = require('pause-stream')
|
|
, split = require('split')
|
|
, pipeline = require('stream-combiner')
|
|
, immediately = global.setImmediate || process.nextTick;
|
|
|
|
es.Stream = Stream //re-export Stream from core
|
|
es.through = through
|
|
es.from = from
|
|
es.duplex = duplex
|
|
es.map = map
|
|
es.pause = pause
|
|
es.split = split
|
|
es.pipeline = es.connect = es.pipe = pipeline
|
|
// merge / concat
|
|
//
|
|
// combine multiple streams into a single stream.
|
|
// will emit end only once
|
|
|
|
es.concat = //actually this should be called concat
|
|
es.merge = function (/*streams...*/) {
|
|
var toMerge = [].slice.call(arguments)
|
|
var stream = new Stream()
|
|
stream.setMaxListeners(0) // allow adding more than 11 streams
|
|
var endCount = 0
|
|
stream.writable = stream.readable = true
|
|
|
|
toMerge.forEach(function (e) {
|
|
e.pipe(stream, {end: false})
|
|
var ended = false
|
|
e.on('end', function () {
|
|
if(ended) return
|
|
ended = true
|
|
endCount ++
|
|
if(endCount == toMerge.length)
|
|
stream.emit('end')
|
|
})
|
|
})
|
|
stream.write = function (data) {
|
|
this.emit('data', data)
|
|
}
|
|
stream.destroy = function () {
|
|
toMerge.forEach(function (e) {
|
|
if(e.destroy) e.destroy()
|
|
})
|
|
}
|
|
return stream
|
|
}
|
|
|
|
|
|
// writable stream, collects all events into an array
|
|
// and calls back when 'end' occurs
|
|
// mainly I'm using this to test the other functions
|
|
|
|
es.writeArray = function (done) {
|
|
if ('function' !== typeof done)
|
|
throw new Error('function writeArray (done): done must be function')
|
|
|
|
var a = new Stream ()
|
|
, array = [], isDone = false
|
|
a.write = function (l) {
|
|
array.push(l)
|
|
}
|
|
a.end = function () {
|
|
isDone = true
|
|
done(null, array)
|
|
}
|
|
a.writable = true
|
|
a.readable = false
|
|
a.destroy = function () {
|
|
a.writable = a.readable = false
|
|
if(isDone) return
|
|
done(new Error('destroyed before end'), array)
|
|
}
|
|
return a
|
|
}
|
|
|
|
//return a Stream that reads the properties of an object
|
|
//respecting pause() and resume()
|
|
|
|
es.readArray = function (array) {
|
|
var stream = new Stream()
|
|
, i = 0
|
|
, paused = false
|
|
, ended = false
|
|
|
|
stream.readable = true
|
|
stream.writable = false
|
|
|
|
if(!Array.isArray(array))
|
|
throw new Error('event-stream.read expects an array')
|
|
|
|
stream.resume = function () {
|
|
if(ended) return
|
|
paused = false
|
|
var l = array.length
|
|
while(i < l && !paused && !ended) {
|
|
stream.emit('data', array[i++])
|
|
}
|
|
if(i == l && !ended)
|
|
ended = true, stream.readable = false, stream.emit('end')
|
|
}
|
|
process.nextTick(stream.resume)
|
|
stream.pause = function () {
|
|
paused = true
|
|
}
|
|
stream.destroy = function () {
|
|
ended = true
|
|
stream.emit('close')
|
|
}
|
|
return stream
|
|
}
|
|
|
|
//
|
|
// readable (asyncFunction)
|
|
// return a stream that calls an async function while the stream is not paused.
|
|
//
|
|
// the function must take: (count, callback) {...
|
|
//
|
|
|
|
es.readable =
|
|
function (func, continueOnError) {
|
|
var stream = new Stream()
|
|
, i = 0
|
|
, paused = false
|
|
, ended = false
|
|
, reading = false
|
|
|
|
stream.readable = true
|
|
stream.writable = false
|
|
|
|
if('function' !== typeof func)
|
|
throw new Error('event-stream.readable expects async function')
|
|
|
|
stream.on('end', function () { ended = true })
|
|
|
|
function get (err, data) {
|
|
|
|
if(err) {
|
|
stream.emit('error', err)
|
|
if(!continueOnError) stream.emit('end')
|
|
} else if (arguments.length > 1)
|
|
stream.emit('data', data)
|
|
|
|
immediately(function () {
|
|
if(ended || paused || reading) return
|
|
try {
|
|
reading = true
|
|
func.call(stream, i++, function () {
|
|
reading = false
|
|
get.apply(null, arguments)
|
|
})
|
|
} catch (err) {
|
|
stream.emit('error', err)
|
|
}
|
|
})
|
|
}
|
|
stream.resume = function () {
|
|
paused = false
|
|
get()
|
|
}
|
|
process.nextTick(get)
|
|
stream.pause = function () {
|
|
paused = true
|
|
}
|
|
stream.destroy = function () {
|
|
stream.emit('end')
|
|
stream.emit('close')
|
|
ended = true
|
|
}
|
|
return stream
|
|
}
|
|
|
|
|
|
//
|
|
// map sync
|
|
//
|
|
|
|
es.mapSync = function (sync) {
|
|
return es.through(function write(data) {
|
|
var mappedData = sync(data)
|
|
if (typeof mappedData !== 'undefined')
|
|
this.emit('data', mappedData)
|
|
})
|
|
}
|
|
|
|
//
|
|
// log just print out what is coming through the stream, for debugging
|
|
//
|
|
|
|
es.log = function (name) {
|
|
return es.through(function (data) {
|
|
var args = [].slice.call(arguments)
|
|
if(name) console.error(name, data)
|
|
else console.error(data)
|
|
this.emit('data', data)
|
|
})
|
|
}
|
|
|
|
|
|
//
|
|
// child -- pipe through a child process
|
|
//
|
|
|
|
es.child = function (child) {
|
|
|
|
return es.duplex(child.stdin, child.stdout)
|
|
|
|
}
|
|
|
|
//
|
|
// parse
|
|
//
|
|
// must be used after es.split() to ensure that each chunk represents a line
|
|
// source.pipe(es.split()).pipe(es.parse())
|
|
|
|
es.parse = function () {
|
|
return es.through(function (data) {
|
|
var obj
|
|
try {
|
|
if(data) //ignore empty lines
|
|
obj = JSON.parse(data.toString())
|
|
} catch (err) {
|
|
return console.error(err, 'attemping to parse:', data)
|
|
}
|
|
//ignore lines that where only whitespace.
|
|
if(obj !== undefined)
|
|
this.emit('data', obj)
|
|
})
|
|
}
|
|
//
|
|
// stringify
|
|
//
|
|
|
|
es.stringify = function () {
|
|
var Buffer = require('buffer').Buffer
|
|
return es.mapSync(function (e){
|
|
return JSON.stringify(Buffer.isBuffer(e) ? e.toString() : e) + '\n'
|
|
})
|
|
}
|
|
|
|
//
|
|
// replace a string within a stream.
|
|
//
|
|
// warn: just concatenates the string and then does str.split().join().
|
|
// probably not optimal.
|
|
// for smallish responses, who cares?
|
|
// I need this for shadow-npm so it's only relatively small json files.
|
|
|
|
es.replace = function (from, to) {
|
|
return es.pipeline(es.split(from), es.join(to))
|
|
}
|
|
|
|
//
|
|
// join chunks with a joiner. just like Array#join
|
|
// also accepts a callback that is passed the chunks appended together
|
|
// this is still supported for legacy reasons.
|
|
//
|
|
|
|
es.join = function (str) {
|
|
|
|
//legacy api
|
|
if('function' === typeof str)
|
|
return es.wait(str)
|
|
|
|
var first = true
|
|
return es.through(function (data) {
|
|
if(!first)
|
|
this.emit('data', str)
|
|
first = false
|
|
this.emit('data', data)
|
|
return true
|
|
})
|
|
}
|
|
|
|
|
|
//
|
|
// wait. callback when 'end' is emitted, with all chunks appended as string.
|
|
//
|
|
|
|
es.wait = function (callback) {
|
|
var arr = []
|
|
return es.through(function (data) { arr.push(data) },
|
|
function () {
|
|
var body = Buffer.isBuffer(arr[0]) ? Buffer.concat(arr)
|
|
: arr.join('')
|
|
this.emit('data', body)
|
|
this.emit('end')
|
|
if(callback) callback(null, body)
|
|
})
|
|
}
|
|
|
|
es.pipeable = function () {
|
|
throw new Error('[EVENT-STREAM] es.pipeable is deprecated')
|
|
}
|