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diff --git a/addon-sdk/source/lib/sdk/io/text-streams.js b/addon-sdk/source/lib/sdk/io/text-streams.js
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+/* 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;
+}