Sharkey/packages/megalodon/src/parser.ts

87 lines
2.2 KiB
TypeScript

import { EventEmitter } from 'events'
import Entity from './entity'
/**
* Parser
* Parse response data in streaming.
**/
export class Parser extends EventEmitter {
private message: string
constructor() {
super()
this.message = ''
}
public parse(chunk: string) {
// skip heartbeats
if (chunk === ':thump\n') {
this.emit('heartbeat', {})
return
}
this.message += chunk
chunk = this.message
const size: number = chunk.length
let start: number = 0
let offset: number = 0
let curr: string | undefined
let next: string | undefined
while (offset < size) {
curr = chunk[offset]
next = chunk[offset + 1]
if (curr === '\n' && next === '\n') {
const piece: string = chunk.slice(start, offset)
offset += 2
start = offset
if (!piece.length) continue // empty object
const root: Array<string> = piece.split('\n')
// should never happen, as long as mastodon doesn't change API messages
if (root.length !== 2) continue
// remove event and data markers
const event: string = root[0].substr(7)
const data: string = root[1].substr(6)
let jsonObj = {}
try {
jsonObj = JSON.parse(data)
} catch (err) {
// delete event does not have json object
if (event !== 'delete') {
this.emit('error', new Error(`Error parsing API reply: '${piece}', error message: '${err}'`))
continue
}
}
switch (event) {
case 'update':
this.emit('update', jsonObj as Entity.Status)
break
case 'notification':
this.emit('notification', jsonObj as Entity.Notification)
break
case 'conversation':
this.emit('conversation', jsonObj as Entity.Conversation)
break
case 'delete':
// When delete, data is an ID of the deleted status
this.emit('delete', data)
break
default:
this.emit('error', new Error(`Unknown event has received: ${event}`))
continue
}
}
offset++
}
this.message = chunk.slice(start, size)
}
}