81 lines
1.8 KiB
JavaScript
81 lines
1.8 KiB
JavaScript
const Duplex = require('readable-stream').Duplex
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const inherits = require('util').inherits
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const noop = function () {}
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module.exports = PortDuplexStream
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inherits(PortDuplexStream, Duplex)
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/**
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* Creates a stream that's both readable and writable.
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* The stream supports arbitrary objects.
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*
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* @class
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* @param {Object} port Remote Port object
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*/
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function PortDuplexStream (port) {
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Duplex.call(this, {
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objectMode: true,
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})
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this._port = port
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port.onMessage.addListener(this._onMessage.bind(this))
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port.onDisconnect.addListener(this._onDisconnect.bind(this))
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}
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/**
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* Callback triggered when a message is received from
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* the remote Port associated with this Stream.
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*
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* @private
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* @param {Object} msg - Payload from the onMessage listener of Port
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*/
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PortDuplexStream.prototype._onMessage = function (msg) {
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if (Buffer.isBuffer(msg)) {
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delete msg._isBuffer
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var data = new Buffer(msg)
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this.push(data)
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} else {
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this.push(msg)
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}
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}
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/**
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* Callback triggered when the remote Port
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* associated with this Stream disconnects.
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*
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* @private
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*/
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PortDuplexStream.prototype._onDisconnect = function () {
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this.destroy()
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}
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/**
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* Explicitly sets read operations to a no-op
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*/
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PortDuplexStream.prototype._read = noop
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/**
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* Called internally when data should be written to
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* this writable stream.
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*
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* @private
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* @param {*} msg Arbitrary object to write
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* @param {string} encoding Encoding to use when writing payload
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* @param {Function} cb Called when writing is complete or an error occurs
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*/
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PortDuplexStream.prototype._write = function (msg, encoding, cb) {
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try {
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if (Buffer.isBuffer(msg)) {
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var data = msg.toJSON()
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data._isBuffer = true
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this._port.postMessage(data)
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} else {
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this._port.postMessage(msg)
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}
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} catch (err) {
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return cb(new Error('PortDuplexStream - disconnected'))
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}
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cb()
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}
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