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/* -*- Mode: js; js-indent-level: 2; indent-tabs-mode: nil; tab-width: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
/* jshint esnext: true, moz: true */
'use strict';
this.EXPORTED_SYMBOLS = ['DataWriter'];
class DataWriter {
constructor(data, maxBytes = 512) {
if (typeof data === 'number') {
maxBytes = data;
data = undefined;
}
this._buffer = new ArrayBuffer(maxBytes);
this._data = new Uint8Array(this._buffer);
this._cursor = 0;
if (data) {
this.putBytes(data);
}
}
get buffer() {
return this._buffer.slice(0, this._cursor);
}
get data() {
return new Uint8Array(this.buffer);
}
// `data` is `Uint8Array`
putBytes(data) {
if (this._cursor + data.length > this._data.length) {
throw new Error('DataWriter buffer is exceeded');
}
for (let i = 0, length = data.length; i < length; i++) {
this._data[this._cursor] = data[i];
this._cursor++;
}
}
putByte(byte) {
if (this._cursor + 1 > this._data.length) {
throw new Error('DataWriter buffer is exceeded');
}
this._data[this._cursor] = byte
this._cursor++;
}
putValue(value, length) {
length = length || 1;
if (length == 1) {
this.putByte(value);
} else {
this.putBytes(_valueToUint8Array(value, length));
}
}
putLabel(label) {
// Eliminate any trailing '.'s in the label (valid in text representation).
label = label.replace(/\.$/, '');
let parts = label.split('.');
parts.forEach((part) => {
this.putLengthString(part);
});
this.putValue(0);
}
putLengthString(string) {
if (string.length > 0xff) {
throw new Error("String too long.");
}
this.putValue(string.length);
for (let i = 0; i < string.length; i++) {
this.putValue(string.charCodeAt(i));
}
}
}
/**
* @private
*/
function _valueToUint8Array(value, length) {
let arrayBuffer = new ArrayBuffer(length);
let uint8Array = new Uint8Array(arrayBuffer);
for (let i = length - 1; i >= 0; i--) {
uint8Array[i] = value & 0xff;
value = value >> 8;
}
return uint8Array;
}
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