1 files changed, 235 insertions, 0 deletions
diff --git a/toolkit/jetpack/sdk/io/text-streams.js b/toolkit/jetpack/sdk/io/text-streams.js
new file mode 100644
index 000000000..ed4ec4972
--- /dev/null
+++ b/toolkit/jetpack/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;
+}