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