File: //opt/coauthor/node_modules/lib0/encoding.js
/**
* Efficient schema-less binary encoding with support for variable length encoding.
*
* Use [lib0/encoding] with [lib0/decoding]. Every encoding function has a corresponding decoding function.
*
* Encodes numbers in little-endian order (least to most significant byte order)
* and is compatible with Golang's binary encoding (https://golang.org/pkg/encoding/binary/)
* which is also used in Protocol Buffers.
*
* ```js
* // encoding step
* const encoder = encoding.createEncoder()
* encoding.writeVarUint(encoder, 256)
* encoding.writeVarString(encoder, 'Hello world!')
* const buf = encoding.toUint8Array(encoder)
* ```
*
* ```js
* // decoding step
* const decoder = decoding.createDecoder(buf)
* decoding.readVarUint(decoder) // => 256
* decoding.readVarString(decoder) // => 'Hello world!'
* decoding.hasContent(decoder) // => false - all data is read
* ```
*
* @module encoding
*/
import * as math from './math.js'
import * as number from './number.js'
import * as binary from './binary.js'
import * as string from './string.js'
import * as array from './array.js'
/**
* A BinaryEncoder handles the encoding to an Uint8Array.
*/
export class Encoder {
constructor () {
this.cpos = 0
this.cbuf = new Uint8Array(100)
/**
* @type {Array<Uint8Array>}
*/
this.bufs = []
}
}
/**
* @function
* @return {Encoder}
*/
export const createEncoder = () => new Encoder()
/**
* @param {function(Encoder):void} f
*/
export const encode = (f) => {
const encoder = createEncoder()
f(encoder)
return toUint8Array(encoder)
}
/**
* The current length of the encoded data.
*
* @function
* @param {Encoder} encoder
* @return {number}
*/
export const length = encoder => {
let len = encoder.cpos
for (let i = 0; i < encoder.bufs.length; i++) {
len += encoder.bufs[i].length
}
return len
}
/**
* Check whether encoder is empty.
*
* @function
* @param {Encoder} encoder
* @return {boolean}
*/
export const hasContent = encoder => encoder.cpos > 0 || encoder.bufs.length > 0
/**
* Transform to Uint8Array.
*
* @function
* @param {Encoder} encoder
* @return {Uint8Array} The created ArrayBuffer.
*/
export const toUint8Array = encoder => {
const uint8arr = new Uint8Array(length(encoder))
let curPos = 0
for (let i = 0; i < encoder.bufs.length; i++) {
const d = encoder.bufs[i]
uint8arr.set(d, curPos)
curPos += d.length
}
uint8arr.set(new Uint8Array(encoder.cbuf.buffer, 0, encoder.cpos), curPos)
return uint8arr
}
/**
* Verify that it is possible to write `len` bytes wtihout checking. If
* necessary, a new Buffer with the required length is attached.
*
* @param {Encoder} encoder
* @param {number} len
*/
export const verifyLen = (encoder, len) => {
const bufferLen = encoder.cbuf.length
if (bufferLen - encoder.cpos < len) {
encoder.bufs.push(new Uint8Array(encoder.cbuf.buffer, 0, encoder.cpos))
encoder.cbuf = new Uint8Array(math.max(bufferLen, len) * 2)
encoder.cpos = 0
}
}
/**
* Write one byte to the encoder.
*
* @function
* @param {Encoder} encoder
* @param {number} num The byte that is to be encoded.
*/
export const write = (encoder, num) => {
const bufferLen = encoder.cbuf.length
if (encoder.cpos === bufferLen) {
encoder.bufs.push(encoder.cbuf)
encoder.cbuf = new Uint8Array(bufferLen * 2)
encoder.cpos = 0
}
encoder.cbuf[encoder.cpos++] = num
}
/**
* Write one byte at a specific position.
* Position must already be written (i.e. encoder.length > pos)
*
* @function
* @param {Encoder} encoder
* @param {number} pos Position to which to write data
* @param {number} num Unsigned 8-bit integer
*/
export const set = (encoder, pos, num) => {
let buffer = null
// iterate all buffers and adjust position
for (let i = 0; i < encoder.bufs.length && buffer === null; i++) {
const b = encoder.bufs[i]
if (pos < b.length) {
buffer = b // found buffer
} else {
pos -= b.length
}
}
if (buffer === null) {
// use current buffer
buffer = encoder.cbuf
}
buffer[pos] = num
}
/**
* Write one byte as an unsigned integer.
*
* @function
* @param {Encoder} encoder
* @param {number} num The number that is to be encoded.
*/
export const writeUint8 = write
/**
* Write one byte as an unsigned Integer at a specific location.
*
* @function
* @param {Encoder} encoder
* @param {number} pos The location where the data will be written.
* @param {number} num The number that is to be encoded.
*/
export const setUint8 = set
/**
* Write two bytes as an unsigned integer.
*
* @function
* @param {Encoder} encoder
* @param {number} num The number that is to be encoded.
*/
export const writeUint16 = (encoder, num) => {
write(encoder, num & binary.BITS8)
write(encoder, (num >>> 8) & binary.BITS8)
}
/**
* Write two bytes as an unsigned integer at a specific location.
*
* @function
* @param {Encoder} encoder
* @param {number} pos The location where the data will be written.
* @param {number} num The number that is to be encoded.
*/
export const setUint16 = (encoder, pos, num) => {
set(encoder, pos, num & binary.BITS8)
set(encoder, pos + 1, (num >>> 8) & binary.BITS8)
}
/**
* Write two bytes as an unsigned integer
*
* @function
* @param {Encoder} encoder
* @param {number} num The number that is to be encoded.
*/
export const writeUint32 = (encoder, num) => {
for (let i = 0; i < 4; i++) {
write(encoder, num & binary.BITS8)
num >>>= 8
}
}
/**
* Write two bytes as an unsigned integer in big endian order.
* (most significant byte first)
*
* @function
* @param {Encoder} encoder
* @param {number} num The number that is to be encoded.
*/
export const writeUint32BigEndian = (encoder, num) => {
for (let i = 3; i >= 0; i--) {
write(encoder, (num >>> (8 * i)) & binary.BITS8)
}
}
/**
* Write two bytes as an unsigned integer at a specific location.
*
* @function
* @param {Encoder} encoder
* @param {number} pos The location where the data will be written.
* @param {number} num The number that is to be encoded.
*/
export const setUint32 = (encoder, pos, num) => {
for (let i = 0; i < 4; i++) {
set(encoder, pos + i, num & binary.BITS8)
num >>>= 8
}
}
/**
* Write a variable length unsigned integer. Max encodable integer is 2^53.
*
* @function
* @param {Encoder} encoder
* @param {number} num The number that is to be encoded.
*/
export const writeVarUint = (encoder, num) => {
while (num > binary.BITS7) {
write(encoder, binary.BIT8 | (binary.BITS7 & num))
num = math.floor(num / 128) // shift >>> 7
}
write(encoder, binary.BITS7 & num)
}
/**
* Write a variable length integer.
*
* We use the 7th bit instead for signaling that this is a negative number.
*
* @function
* @param {Encoder} encoder
* @param {number} num The number that is to be encoded.
*/
export const writeVarInt = (encoder, num) => {
const isNegative = math.isNegativeZero(num)
if (isNegative) {
num = -num
}
// |- whether to continue reading |- whether is negative |- number
write(encoder, (num > binary.BITS6 ? binary.BIT8 : 0) | (isNegative ? binary.BIT7 : 0) | (binary.BITS6 & num))
num = math.floor(num / 64) // shift >>> 6
// We don't need to consider the case of num === 0 so we can use a different
// pattern here than above.
while (num > 0) {
write(encoder, (num > binary.BITS7 ? binary.BIT8 : 0) | (binary.BITS7 & num))
num = math.floor(num / 128) // shift >>> 7
}
}
/**
* A cache to store strings temporarily
*/
const _strBuffer = new Uint8Array(30000)
const _maxStrBSize = _strBuffer.length / 3
/**
* Write a variable length string.
*
* @function
* @param {Encoder} encoder
* @param {String} str The string that is to be encoded.
*/
export const _writeVarStringNative = (encoder, str) => {
if (str.length < _maxStrBSize) {
// We can encode the string into the existing buffer
/* c8 ignore next */
const written = string.utf8TextEncoder.encodeInto(str, _strBuffer).written || 0
writeVarUint(encoder, written)
for (let i = 0; i < written; i++) {
write(encoder, _strBuffer[i])
}
} else {
writeVarUint8Array(encoder, string.encodeUtf8(str))
}
}
/**
* Write a variable length string.
*
* @function
* @param {Encoder} encoder
* @param {String} str The string that is to be encoded.
*/
export const _writeVarStringPolyfill = (encoder, str) => {
const encodedString = unescape(encodeURIComponent(str))
const len = encodedString.length
writeVarUint(encoder, len)
for (let i = 0; i < len; i++) {
write(encoder, /** @type {number} */ (encodedString.codePointAt(i)))
}
}
/**
* Write a variable length string.
*
* @function
* @param {Encoder} encoder
* @param {String} str The string that is to be encoded.
*/
/* c8 ignore next */
export const writeVarString = (string.utf8TextEncoder && /** @type {any} */ (string.utf8TextEncoder).encodeInto) ? _writeVarStringNative : _writeVarStringPolyfill
/**
* Write a string terminated by a special byte sequence. This is not very performant and is
* generally discouraged. However, the resulting byte arrays are lexiographically ordered which
* makes this a nice feature for databases.
*
* The string will be encoded using utf8 and then terminated and escaped using writeTerminatingUint8Array.
*
* @function
* @param {Encoder} encoder
* @param {String} str The string that is to be encoded.
*/
export const writeTerminatedString = (encoder, str) =>
writeTerminatedUint8Array(encoder, string.encodeUtf8(str))
/**
* Write a terminating Uint8Array. Note that this is not performant and is generally
* discouraged. There are few situations when this is needed.
*
* We use 0x0 as a terminating character. 0x1 serves as an escape character for 0x0 and 0x1.
*
* Example: [0,1,2] is encoded to [1,0,1,1,2,0]. 0x0, and 0x1 needed to be escaped using 0x1. Then
* the result is terminated using the 0x0 character.
*
* This is basically how many systems implement null terminated strings. However, we use an escape
* character 0x1 to avoid issues and potenial attacks on our database (if this is used as a key
* encoder for NoSql databases).
*
* @function
* @param {Encoder} encoder
* @param {Uint8Array} buf The string that is to be encoded.
*/
export const writeTerminatedUint8Array = (encoder, buf) => {
for (let i = 0; i < buf.length; i++) {
const b = buf[i]
if (b === 0 || b === 1) {
write(encoder, 1)
}
write(encoder, buf[i])
}
write(encoder, 0)
}
/**
* Write the content of another Encoder.
*
* @TODO: can be improved!
* - Note: Should consider that when appending a lot of small Encoders, we should rather clone than referencing the old structure.
* Encoders start with a rather big initial buffer.
*
* @function
* @param {Encoder} encoder The enUint8Arr
* @param {Encoder} append The BinaryEncoder to be written.
*/
export const writeBinaryEncoder = (encoder, append) => writeUint8Array(encoder, toUint8Array(append))
/**
* Append fixed-length Uint8Array to the encoder.
*
* @function
* @param {Encoder} encoder
* @param {Uint8Array} uint8Array
*/
export const writeUint8Array = (encoder, uint8Array) => {
const bufferLen = encoder.cbuf.length
const cpos = encoder.cpos
const leftCopyLen = math.min(bufferLen - cpos, uint8Array.length)
const rightCopyLen = uint8Array.length - leftCopyLen
encoder.cbuf.set(uint8Array.subarray(0, leftCopyLen), cpos)
encoder.cpos += leftCopyLen
if (rightCopyLen > 0) {
// Still something to write, write right half..
// Append new buffer
encoder.bufs.push(encoder.cbuf)
// must have at least size of remaining buffer
encoder.cbuf = new Uint8Array(math.max(bufferLen * 2, rightCopyLen))
// copy array
encoder.cbuf.set(uint8Array.subarray(leftCopyLen))
encoder.cpos = rightCopyLen
}
}
/**
* Append an Uint8Array to Encoder.
*
* @function
* @param {Encoder} encoder
* @param {Uint8Array} uint8Array
*/
export const writeVarUint8Array = (encoder, uint8Array) => {
writeVarUint(encoder, uint8Array.byteLength)
writeUint8Array(encoder, uint8Array)
}
/**
* Create an DataView of the next `len` bytes. Use it to write data after
* calling this function.
*
* ```js
* // write float32 using DataView
* const dv = writeOnDataView(encoder, 4)
* dv.setFloat32(0, 1.1)
* // read float32 using DataView
* const dv = readFromDataView(encoder, 4)
* dv.getFloat32(0) // => 1.100000023841858 (leaving it to the reader to find out why this is the correct result)
* ```
*
* @param {Encoder} encoder
* @param {number} len
* @return {DataView}
*/
export const writeOnDataView = (encoder, len) => {
verifyLen(encoder, len)
const dview = new DataView(encoder.cbuf.buffer, encoder.cpos, len)
encoder.cpos += len
return dview
}
/**
* @param {Encoder} encoder
* @param {number} num
*/
export const writeFloat32 = (encoder, num) => writeOnDataView(encoder, 4).setFloat32(0, num, false)
/**
* @param {Encoder} encoder
* @param {number} num
*/
export const writeFloat64 = (encoder, num) => writeOnDataView(encoder, 8).setFloat64(0, num, false)
/**
* @param {Encoder} encoder
* @param {bigint} num
*/
export const writeBigInt64 = (encoder, num) => /** @type {any} */ (writeOnDataView(encoder, 8)).setBigInt64(0, num, false)
/**
* @param {Encoder} encoder
* @param {bigint} num
*/
export const writeBigUint64 = (encoder, num) => /** @type {any} */ (writeOnDataView(encoder, 8)).setBigUint64(0, num, false)
const floatTestBed = new DataView(new ArrayBuffer(4))
/**
* Check if a number can be encoded as a 32 bit float.
*
* @param {number} num
* @return {boolean}
*/
const isFloat32 = num => {
floatTestBed.setFloat32(0, num)
return floatTestBed.getFloat32(0) === num
}
/**
* Encode data with efficient binary format.
*
* Differences to JSON:
* • Transforms data to a binary format (not to a string)
* • Encodes undefined, NaN, and ArrayBuffer (these can't be represented in JSON)
* • Numbers are efficiently encoded either as a variable length integer, as a
* 32 bit float, as a 64 bit float, or as a 64 bit bigint.
*
* Encoding table:
*
* | Data Type | Prefix | Encoding Method | Comment |
* | ------------------- | -------- | ------------------ | ------- |
* | undefined | 127 | | Functions, symbol, and everything that cannot be identified is encoded as undefined |
* | null | 126 | | |
* | integer | 125 | writeVarInt | Only encodes 32 bit signed integers |
* | float32 | 124 | writeFloat32 | |
* | float64 | 123 | writeFloat64 | |
* | bigint | 122 | writeBigInt64 | |
* | boolean (false) | 121 | | True and false are different data types so we save the following byte |
* | boolean (true) | 120 | | - 0b01111000 so the last bit determines whether true or false |
* | string | 119 | writeVarString | |
* | object<string,any> | 118 | custom | Writes {length} then {length} key-value pairs |
* | array<any> | 117 | custom | Writes {length} then {length} json values |
* | Uint8Array | 116 | writeVarUint8Array | We use Uint8Array for any kind of binary data |
*
* Reasons for the decreasing prefix:
* We need the first bit for extendability (later we may want to encode the
* prefix with writeVarUint). The remaining 7 bits are divided as follows:
* [0-30] the beginning of the data range is used for custom purposes
* (defined by the function that uses this library)
* [31-127] the end of the data range is used for data encoding by
* lib0/encoding.js
*
* @param {Encoder} encoder
* @param {undefined|null|number|bigint|boolean|string|Object<string,any>|Array<any>|Uint8Array} data
*/
export const writeAny = (encoder, data) => {
switch (typeof data) {
case 'string':
// TYPE 119: STRING
write(encoder, 119)
writeVarString(encoder, data)
break
case 'number':
if (number.isInteger(data) && math.abs(data) <= binary.BITS31) {
// TYPE 125: INTEGER
write(encoder, 125)
writeVarInt(encoder, data)
} else if (isFloat32(data)) {
// TYPE 124: FLOAT32
write(encoder, 124)
writeFloat32(encoder, data)
} else {
// TYPE 123: FLOAT64
write(encoder, 123)
writeFloat64(encoder, data)
}
break
case 'bigint':
// TYPE 122: BigInt
write(encoder, 122)
writeBigInt64(encoder, data)
break
case 'object':
if (data === null) {
// TYPE 126: null
write(encoder, 126)
} else if (array.isArray(data)) {
// TYPE 117: Array
write(encoder, 117)
writeVarUint(encoder, data.length)
for (let i = 0; i < data.length; i++) {
writeAny(encoder, data[i])
}
} else if (data instanceof Uint8Array) {
// TYPE 116: ArrayBuffer
write(encoder, 116)
writeVarUint8Array(encoder, data)
} else {
// TYPE 118: Object
write(encoder, 118)
const keys = Object.keys(data)
writeVarUint(encoder, keys.length)
for (let i = 0; i < keys.length; i++) {
const key = keys[i]
writeVarString(encoder, key)
writeAny(encoder, data[key])
}
}
break
case 'boolean':
// TYPE 120/121: boolean (true/false)
write(encoder, data ? 120 : 121)
break
default:
// TYPE 127: undefined
write(encoder, 127)
}
}
/**
* Now come a few stateful encoder that have their own classes.
*/
/**
* Basic Run Length Encoder - a basic compression implementation.
*
* Encodes [1,1,1,7] to [1,3,7,1] (3 times 1, 1 time 7). This encoder might do more harm than good if there are a lot of values that are not repeated.
*
* It was originally used for image compression. Cool .. article http://csbruce.com/cbm/transactor/pdfs/trans_v7_i06.pdf
*
* @note T must not be null!
*
* @template T
*/
export class RleEncoder extends Encoder {
/**
* @param {function(Encoder, T):void} writer
*/
constructor (writer) {
super()
/**
* The writer
*/
this.w = writer
/**
* Current state
* @type {T|null}
*/
this.s = null
this.count = 0
}
/**
* @param {T} v
*/
write (v) {
if (this.s === v) {
this.count++
} else {
if (this.count > 0) {
// flush counter, unless this is the first value (count = 0)
writeVarUint(this, this.count - 1) // since count is always > 0, we can decrement by one. non-standard encoding ftw
}
this.count = 1
// write first value
this.w(this, v)
this.s = v
}
}
}
/**
* Basic diff decoder using variable length encoding.
*
* Encodes the values [3, 1100, 1101, 1050, 0] to [3, 1097, 1, -51, -1050] using writeVarInt.
*/
export class IntDiffEncoder extends Encoder {
/**
* @param {number} start
*/
constructor (start) {
super()
/**
* Current state
* @type {number}
*/
this.s = start
}
/**
* @param {number} v
*/
write (v) {
writeVarInt(this, v - this.s)
this.s = v
}
}
/**
* A combination of IntDiffEncoder and RleEncoder.
*
* Basically first writes the IntDiffEncoder and then counts duplicate diffs using RleEncoding.
*
* Encodes the values [1,1,1,2,3,4,5,6] as [1,1,0,2,1,5] (RLE([1,0,0,1,1,1,1,1]) ⇒ RleIntDiff[1,1,0,2,1,5])
*/
export class RleIntDiffEncoder extends Encoder {
/**
* @param {number} start
*/
constructor (start) {
super()
/**
* Current state
* @type {number}
*/
this.s = start
this.count = 0
}
/**
* @param {number} v
*/
write (v) {
if (this.s === v && this.count > 0) {
this.count++
} else {
if (this.count > 0) {
// flush counter, unless this is the first value (count = 0)
writeVarUint(this, this.count - 1) // since count is always > 0, we can decrement by one. non-standard encoding ftw
}
this.count = 1
// write first value
writeVarInt(this, v - this.s)
this.s = v
}
}
}
/**
* @param {UintOptRleEncoder} encoder
*/
const flushUintOptRleEncoder = encoder => {
if (encoder.count > 0) {
// flush counter, unless this is the first value (count = 0)
// case 1: just a single value. set sign to positive
// case 2: write several values. set sign to negative to indicate that there is a length coming
writeVarInt(encoder.encoder, encoder.count === 1 ? encoder.s : -encoder.s)
if (encoder.count > 1) {
writeVarUint(encoder.encoder, encoder.count - 2) // since count is always > 1, we can decrement by one. non-standard encoding ftw
}
}
}
/**
* Optimized Rle encoder that does not suffer from the mentioned problem of the basic Rle encoder.
*
* Internally uses VarInt encoder to write unsigned integers. If the input occurs multiple times, we write
* write it as a negative number. The UintOptRleDecoder then understands that it needs to read a count.
*
* Encodes [1,2,3,3,3] as [1,2,-3,3] (once 1, once 2, three times 3)
*/
export class UintOptRleEncoder {
constructor () {
this.encoder = new Encoder()
/**
* @type {number}
*/
this.s = 0
this.count = 0
}
/**
* @param {number} v
*/
write (v) {
if (this.s === v) {
this.count++
} else {
flushUintOptRleEncoder(this)
this.count = 1
this.s = v
}
}
/**
* Flush the encoded state and transform this to a Uint8Array.
*
* Note that this should only be called once.
*/
toUint8Array () {
flushUintOptRleEncoder(this)
return toUint8Array(this.encoder)
}
}
/**
* Increasing Uint Optimized RLE Encoder
*
* The RLE encoder counts the number of same occurences of the same value.
* The IncUintOptRle encoder counts if the value increases.
* I.e. 7, 8, 9, 10 will be encoded as [-7, 4]. 1, 3, 5 will be encoded
* as [1, 3, 5].
*/
export class IncUintOptRleEncoder {
constructor () {
this.encoder = new Encoder()
/**
* @type {number}
*/
this.s = 0
this.count = 0
}
/**
* @param {number} v
*/
write (v) {
if (this.s + this.count === v) {
this.count++
} else {
flushUintOptRleEncoder(this)
this.count = 1
this.s = v
}
}
/**
* Flush the encoded state and transform this to a Uint8Array.
*
* Note that this should only be called once.
*/
toUint8Array () {
flushUintOptRleEncoder(this)
return toUint8Array(this.encoder)
}
}
/**
* @param {IntDiffOptRleEncoder} encoder
*/
const flushIntDiffOptRleEncoder = encoder => {
if (encoder.count > 0) {
// 31 bit making up the diff | wether to write the counter
// const encodedDiff = encoder.diff << 1 | (encoder.count === 1 ? 0 : 1)
const encodedDiff = encoder.diff * 2 + (encoder.count === 1 ? 0 : 1)
// flush counter, unless this is the first value (count = 0)
// case 1: just a single value. set first bit to positive
// case 2: write several values. set first bit to negative to indicate that there is a length coming
writeVarInt(encoder.encoder, encodedDiff)
if (encoder.count > 1) {
writeVarUint(encoder.encoder, encoder.count - 2) // since count is always > 1, we can decrement by one. non-standard encoding ftw
}
}
}
/**
* A combination of the IntDiffEncoder and the UintOptRleEncoder.
*
* The count approach is similar to the UintDiffOptRleEncoder, but instead of using the negative bitflag, it encodes
* in the LSB whether a count is to be read. Therefore this Encoder only supports 31 bit integers!
*
* Encodes [1, 2, 3, 2] as [3, 1, 6, -1] (more specifically [(1 << 1) | 1, (3 << 0) | 0, -1])
*
* Internally uses variable length encoding. Contrary to normal UintVar encoding, the first byte contains:
* * 1 bit that denotes whether the next value is a count (LSB)
* * 1 bit that denotes whether this value is negative (MSB - 1)
* * 1 bit that denotes whether to continue reading the variable length integer (MSB)
*
* Therefore, only five bits remain to encode diff ranges.
*
* Use this Encoder only when appropriate. In most cases, this is probably a bad idea.
*/
export class IntDiffOptRleEncoder {
constructor () {
this.encoder = new Encoder()
/**
* @type {number}
*/
this.s = 0
this.count = 0
this.diff = 0
}
/**
* @param {number} v
*/
write (v) {
if (this.diff === v - this.s) {
this.s = v
this.count++
} else {
flushIntDiffOptRleEncoder(this)
this.count = 1
this.diff = v - this.s
this.s = v
}
}
/**
* Flush the encoded state and transform this to a Uint8Array.
*
* Note that this should only be called once.
*/
toUint8Array () {
flushIntDiffOptRleEncoder(this)
return toUint8Array(this.encoder)
}
}
/**
* Optimized String Encoder.
*
* Encoding many small strings in a simple Encoder is not very efficient. The function call to decode a string takes some time and creates references that must be eventually deleted.
* In practice, when decoding several million small strings, the GC will kick in more and more often to collect orphaned string objects (or maybe there is another reason?).
*
* This string encoder solves the above problem. All strings are concatenated and written as a single string using a single encoding call.
*
* The lengths are encoded using a UintOptRleEncoder.
*/
export class StringEncoder {
constructor () {
/**
* @type {Array<string>}
*/
this.sarr = []
this.s = ''
this.lensE = new UintOptRleEncoder()
}
/**
* @param {string} string
*/
write (string) {
this.s += string
if (this.s.length > 19) {
this.sarr.push(this.s)
this.s = ''
}
this.lensE.write(string.length)
}
toUint8Array () {
const encoder = new Encoder()
this.sarr.push(this.s)
this.s = ''
writeVarString(encoder, this.sarr.join(''))
writeUint8Array(encoder, this.lensE.toUint8Array())
return toUint8Array(encoder)
}
}