Files
yjs/src/Binary/Encoder.js
2017-10-23 22:43:41 +02:00

84 lines
1.6 KiB
JavaScript

import utf8 from 'utf-8'
import { RootFakeUserID } from '../Util/RootID.js'
const bits7 = 0b1111111
const bits8 = 0b11111111
export default class BinaryEncoder {
constructor () {
// TODO: implement chained Uint8Array buffers instead of Array buffer
this.data = []
}
get length () {
return this.data.length
}
get pos () {
return this.data.length
}
createBuffer () {
return Uint8Array.from(this.data).buffer
}
writeUint8 (num) {
this.data.push(num & bits8)
}
setUint8 (pos, num) {
this.data[pos] = num & bits8
}
writeUint16 (num) {
this.data.push(num & bits8, (num >>> 8) & bits8)
}
setUint16 (pos, num) {
this.data[pos] = num & bits8
this.data[pos + 1] = (num >>> 8) & bits8
}
writeUint32 (num) {
for (let i = 0; i < 4; i++) {
this.data.push(num & bits8)
num >>>= 8
}
}
setUint32 (pos, num) {
for (let i = 0; i < 4; i++) {
this.data[pos + i] = num & bits8
num >>>= 8
}
}
writeVarUint (num) {
while (num >= 0b10000000) {
this.data.push(0b10000000 | (bits7 & num))
num >>>= 7
}
this.data.push(bits7 & num)
}
writeVarString (str) {
let bytes = utf8.setBytesFromString(str)
let len = bytes.length
this.writeVarUint(len)
for (let i = 0; i < len; i++) {
this.data.push(bytes[i])
}
}
writeID (id) {
const user = id.user
this.writeVarUint(user)
if (user !== RootFakeUserID) {
this.writeVarUint(id.clock)
} else {
this.writeVarString(id.name)
this.writeVarUint(id.type)
}
}
}