diff options
Diffstat (limited to 'addon-sdk/source/lib/sdk/io/text-streams.js')
-rw-r--r-- | addon-sdk/source/lib/sdk/io/text-streams.js | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/addon-sdk/source/lib/sdk/io/text-streams.js b/addon-sdk/source/lib/sdk/io/text-streams.js new file mode 100644 index 000000000..ed4ec4972 --- /dev/null +++ b/addon-sdk/source/lib/sdk/io/text-streams.js @@ -0,0 +1,235 @@ +/* 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; +} |