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