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metamask-extension/app/scripts/lib/port-stream.js
2018-07-02 18:49:33 -04:00

81 lines
1.8 KiB
JavaScript

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