236 lines
7.6 KiB
JavaScript
236 lines
7.6 KiB
JavaScript
/* 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
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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"use strict";
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module.metadata = {
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"stability": "experimental"
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};
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const { Cc, Ci, Cu, components } = require("chrome");
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const { ensure } = require("../system/unload");
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const { NetUtil } = Cu.import("resource://gre/modules/NetUtil.jsm", {});
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// NetUtil.asyncCopy() uses this buffer length, and since we call it, for best
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// performance we use it, too.
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const BUFFER_BYTE_LEN = 0x8000;
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const PR_UINT32_MAX = 0xffffffff;
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const DEFAULT_CHARSET = "UTF-8";
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/**
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* An input stream that reads text from a backing stream using a given text
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* encoding.
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*
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* @param inputStream
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* The stream is backed by this nsIInputStream. It must already be
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* opened.
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* @param charset
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* Text in inputStream is expected to be in this character encoding. If
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* not given, "UTF-8" is assumed. See nsICharsetConverterManager.idl for
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* documentation on how to determine other valid values for this.
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*/
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function TextReader(inputStream, charset) {
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charset = checkCharset(charset);
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let stream = Cc["@mozilla.org/intl/converter-input-stream;1"].
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createInstance(Ci.nsIConverterInputStream);
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stream.init(inputStream, charset, BUFFER_BYTE_LEN,
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Ci.nsIConverterInputStream.DEFAULT_REPLACEMENT_CHARACTER);
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let manager = new StreamManager(this, stream);
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/**
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* Reads a string from the stream. If the stream is closed, an exception is
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* thrown.
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*
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* @param numChars
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* The number of characters to read. If not given, the remainder of
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* the stream is read.
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* @return The string read. If the stream is already at EOS, returns the
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* empty string.
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*/
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this.read = function TextReader_read(numChars) {
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manager.ensureOpened();
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let readAll = false;
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if (typeof(numChars) === "number")
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numChars = Math.max(numChars, 0);
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else
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readAll = true;
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let str = "";
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let totalRead = 0;
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let chunkRead = 1;
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// Read in numChars or until EOS, whichever comes first. Note that the
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// units here are characters, not bytes.
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while (true) {
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let chunk = {};
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let toRead = readAll ?
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PR_UINT32_MAX :
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Math.min(numChars - totalRead, PR_UINT32_MAX);
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if (toRead <= 0 || chunkRead <= 0)
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break;
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// The converter stream reads in at most BUFFER_BYTE_LEN bytes in a call
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// to readString, enough to fill its byte buffer. chunkRead will be the
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// number of characters encoded by the bytes in that buffer.
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chunkRead = stream.readString(toRead, chunk);
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str += chunk.value;
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totalRead += chunkRead;
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}
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return str;
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};
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}
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exports.TextReader = TextReader;
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/**
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* A buffered output stream that writes text to a backing stream using a given
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* text encoding.
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*
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* @param outputStream
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* The stream is backed by this nsIOutputStream. It must already be
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* opened.
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* @param charset
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* Text will be written to outputStream using this character encoding.
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* If not given, "UTF-8" is assumed. See nsICharsetConverterManager.idl
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* for documentation on how to determine other valid values for this.
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*/
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function TextWriter(outputStream, charset) {
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charset = checkCharset(charset);
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let stream = outputStream;
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// Buffer outputStream if it's not already.
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let ioUtils = Cc["@mozilla.org/io-util;1"].getService(Ci.nsIIOUtil);
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if (!ioUtils.outputStreamIsBuffered(outputStream)) {
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stream = Cc["@mozilla.org/network/buffered-output-stream;1"].
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createInstance(Ci.nsIBufferedOutputStream);
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stream.init(outputStream, BUFFER_BYTE_LEN);
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}
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// I'd like to use nsIConverterOutputStream. But NetUtil.asyncCopy(), which
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// we use below in writeAsync(), naturally expects its sink to be an instance
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// of nsIOutputStream, which nsIConverterOutputStream's only implementation is
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// not. So we use uconv and manually convert all strings before writing to
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// outputStream.
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let uconv = Cc["@mozilla.org/intl/scriptableunicodeconverter"].
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createInstance(Ci.nsIScriptableUnicodeConverter);
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uconv.charset = charset;
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let manager = new StreamManager(this, stream);
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/**
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* Flushes the backing stream's buffer.
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*/
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this.flush = function TextWriter_flush() {
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manager.ensureOpened();
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stream.flush();
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};
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/**
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* Writes a string to the stream. If the stream is closed, an exception is
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* thrown.
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*
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* @param str
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* The string to write.
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*/
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this.write = function TextWriter_write(str) {
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manager.ensureOpened();
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let istream = uconv.convertToInputStream(str);
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let len = istream.available();
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while (len > 0) {
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stream.writeFrom(istream, len);
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len = istream.available();
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}
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istream.close();
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};
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/**
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* Writes a string on a background thread. After the write completes, the
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* backing stream's buffer is flushed, and both the stream and the backing
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* stream are closed, also on the background thread. If the stream is already
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* closed, an exception is thrown immediately.
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*
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* @param str
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* The string to write.
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* @param callback
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* An optional function. If given, it's called as callback(error) when
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* the write completes. error is an Error object or undefined if there
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* was no error. Inside callback, |this| is the stream object.
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*/
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this.writeAsync = function TextWriter_writeAsync(str, callback) {
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manager.ensureOpened();
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let istream = uconv.convertToInputStream(str);
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NetUtil.asyncCopy(istream, stream, (result) => {
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let err = components.isSuccessCode(result) ? undefined :
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new Error("An error occured while writing to the stream: " + result);
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if (err)
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console.error(err);
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// asyncCopy() closes its output (and input) stream.
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manager.opened = false;
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if (typeof(callback) === "function") {
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try {
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callback.call(this, err);
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}
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catch (exc) {
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console.exception(exc);
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}
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}
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});
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};
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}
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exports.TextWriter = TextWriter;
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// This manages the lifetime of stream, a TextReader or TextWriter. It defines
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// closed and close() on stream and registers an unload listener that closes
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// rawStream if it's still opened. It also provides ensureOpened(), which
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// throws an exception if the stream is closed.
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function StreamManager(stream, rawStream) {
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this.rawStream = rawStream;
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this.opened = true;
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/**
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* True iff the stream is closed.
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*/
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stream.__defineGetter__("closed", () => !this.opened);
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/**
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* Closes both the stream and its backing stream. If the stream is already
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* closed, an exception is thrown. For TextWriters, this first flushes the
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* backing stream's buffer.
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*/
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stream.close = () => {
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this.ensureOpened();
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this.unload();
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};
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ensure(this);
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}
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StreamManager.prototype = {
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ensureOpened: function StreamManager_ensureOpened() {
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if (!this.opened)
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throw new Error("The stream is closed and cannot be used.");
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},
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unload: function StreamManager_unload() {
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// TextWriter.writeAsync() causes rawStream to close and therefore sets
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// opened to false, so check that we're still opened.
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if (this.opened) {
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// Calling close() on both an nsIUnicharInputStream and
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// nsIBufferedOutputStream closes their backing streams. It also forces
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// nsIOutputStreams to flush first.
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this.rawStream.close();
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this.opened = false;
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}
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}
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};
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function checkCharset(charset) {
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return typeof(charset) === "string" ? charset : DEFAULT_CHARSET;
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}
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