| 1 | 'use strict'
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| 2 |
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| 3 | const stream = require('../lib/destroyable-stream')
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| 4 |
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| 5 | const FRAME_PREFIX_SIZE = 2
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| 6 |
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| 7 | class AbstractEncoder extends stream.Transform {
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| 8 | constructor (messageType, options) {
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| 9 | super(Object.assign({
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| 10 | readableObjectMode: false,
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| 11 | writableObjectMode: true
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| 12 | }, options))
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| 13 |
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| 14 | this._messageType = messageType
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| 15 | }
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| 16 |
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| 17 | _transform (message, encoding, callback) {
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| 18 | const messageLength = this._messageType.encodingLength(message)
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| 19 |
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| 20 | const framedMessage = Buffer.alloc(messageLength + FRAME_PREFIX_SIZE)
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| 21 | framedMessage.writeUInt16BE(messageLength, 0)
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| 22 | this._messageType.encode(message, framedMessage, FRAME_PREFIX_SIZE)
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| 23 |
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| 24 | callback(null, framedMessage)
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| 25 | }
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| 26 | }
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| 27 |
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| 28 | module.exports = AbstractEncoder
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