mirror of
https://github.com/JasonYANG170/IOTConnect-Web.git
synced 2024-11-23 20:26:28 +00:00
90 lines
2.8 KiB
JavaScript
90 lines
2.8 KiB
JavaScript
'use strict'
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const { ArrayIsArray, ObjectSetPrototypeOf } = require('../../ours/primordials')
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const { EventEmitter: EE } = require('events')
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function Stream(opts) {
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EE.call(this, opts)
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}
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ObjectSetPrototypeOf(Stream.prototype, EE.prototype)
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ObjectSetPrototypeOf(Stream, EE)
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Stream.prototype.pipe = function (dest, options) {
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const source = this
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function ondata(chunk) {
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if (dest.writable && dest.write(chunk) === false && source.pause) {
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source.pause()
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}
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}
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source.on('data', ondata)
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function ondrain() {
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if (source.readable && source.resume) {
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source.resume()
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}
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}
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dest.on('drain', ondrain)
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// If the 'end' option is not supplied, dest.end() will be called when
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// source gets the 'end' or 'close' events. Only dest.end() once.
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if (!dest._isStdio && (!options || options.end !== false)) {
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source.on('end', onend)
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source.on('close', onclose)
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}
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let didOnEnd = false
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function onend() {
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if (didOnEnd) return
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didOnEnd = true
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dest.end()
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}
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function onclose() {
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if (didOnEnd) return
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didOnEnd = true
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if (typeof dest.destroy === 'function') dest.destroy()
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}
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// Don't leave dangling pipes when there are errors.
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function onerror(er) {
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cleanup()
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if (EE.listenerCount(this, 'error') === 0) {
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this.emit('error', er)
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}
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}
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prependListener(source, 'error', onerror)
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prependListener(dest, 'error', onerror)
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// Remove all the event listeners that were added.
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function cleanup() {
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source.removeListener('data', ondata)
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dest.removeListener('drain', ondrain)
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source.removeListener('end', onend)
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source.removeListener('close', onclose)
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source.removeListener('error', onerror)
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dest.removeListener('error', onerror)
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source.removeListener('end', cleanup)
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source.removeListener('close', cleanup)
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dest.removeListener('close', cleanup)
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}
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source.on('end', cleanup)
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source.on('close', cleanup)
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dest.on('close', cleanup)
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dest.emit('pipe', source)
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// Allow for unix-like usage: A.pipe(B).pipe(C)
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return dest
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}
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function prependListener(emitter, event, fn) {
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// Sadly this is not cacheable as some libraries bundle their own
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// event emitter implementation with them.
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if (typeof emitter.prependListener === 'function') return emitter.prependListener(event, fn)
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// This is a hack to make sure that our error handler is attached before any
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// userland ones. NEVER DO THIS. This is here only because this code needs
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// to continue to work with older versions of Node.js that do not include
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// the prependListener() method. The goal is to eventually remove this hack.
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if (!emitter._events || !emitter._events[event]) emitter.on(event, fn)
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else if (ArrayIsArray(emitter._events[event])) emitter._events[event].unshift(fn)
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else emitter._events[event] = [fn, emitter._events[event]]
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}
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module.exports = {
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Stream,
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prependListener
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}
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