xpcom/io/nsIUnicharInputStream.idl

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "nsISupports.idl"
   7
   8 interface nsIUnicharInputStream;
   9 interface nsIInputStream;
  10
  11 %{C++
  12 /**
  13  * The signature of the writer function passed to ReadSegments. This
  14  * is the "consumer" of data that gets read from the stream's buffer.
  15  *
  16  * @param aInStream stream being read
  17  * @param aClosure opaque parameter passed to ReadSegments
  18  * @param aFromSegment pointer to memory owned by the input stream
  19  * @param aToOffset amount already read (since ReadSegments was called)
  20  * @param aCount length of fromSegment
  21  * @param aWriteCount number of bytes read
  22  *
  23  * Implementers should return the following:
  24  *
  25  * @throws <any-error> if not interested in consuming any data
  26  *
  27  * Errors are never passed to the caller of ReadSegments.
  28  *
  29  * NOTE: returning NS_OK and (*aWriteCount = 0) has undefined behavior.
  30  */
  31 typedef nsresult (*nsWriteUnicharSegmentFun)(nsIUnicharInputStream *aInStream,
  32                                              void *aClosure,
  33                                              const char16_t *aFromSegment,
  34                                              uint32_t aToOffset,
  35                                              uint32_t aCount,
  36                                              uint32_t *aWriteCount);
  37 %}
  38 native nsWriteUnicharSegmentFun(nsWriteUnicharSegmentFun);
  39
  40 /**
  41  * Abstract unicode character input stream
  42  * @see nsIInputStream
  43  */
  44 [scriptable, uuid(d5e3bd80-6723-4b92-b0c9-22f6162fd94f)]
  45 interface nsIUnicharInputStream : nsISupports {
  46   /**
  47    * Reads into a caller-provided character array.
  48    *
  49    * @return The number of characters that were successfully read. May be less
  50    *         than aCount, even if there is more data in the input stream.
  51    *         A return value of 0 means EOF.
  52    *
  53    * @note To read more than 2^32 characters, call this method multiple times.
  54    */
  55   [noscript] unsigned long read([array, size_is(aCount)] in char16_t aBuf,
  56                                 in unsigned long aCount);
  57
  58   /**
  59    * Low-level read method that has access to the stream's underlying buffer.
  60    * The writer function may be called multiple times for segmented buffers.
  61    * ReadSegments is expected to keep calling the writer until either there is
  62    * nothing left to read or the writer returns an error.  ReadSegments should
  63    * not call the writer with zero characters to consume.
  64    *
  65    * @param aWriter the "consumer" of the data to be read
  66    * @param aClosure opaque parameter passed to writer
  67    * @param aCount the maximum number of characters to be read
  68    *
  69    * @return number of characters read (may be less than aCount)
  70    * @return 0 if reached end of file (or if aWriter refused to consume data)
  71    *
  72    * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would
  73    *   block the calling thread (non-blocking mode only)
  74    * @throws <other-error> on failure
  75    *
  76    * NOTE: this function may be unimplemented if a stream has no underlying
  77    * buffer
  78    */
  79   [noscript] unsigned long readSegments(in nsWriteUnicharSegmentFun aWriter,
  80                                         in voidPtr aClosure,
  81                                         in unsigned long aCount);
  82
  83   /**
  84    * Read into a string object.
  85    * @param aCount The number of characters that should be read
  86    * @return The number of characters that were read.
  87    */
  88   unsigned long readString(in unsigned long aCount, out AString aString);
  89
  90  /**
  91   * Close the stream and free associated resources. This also closes the
  92   * underlying stream, if any.
  93   */
  94   void close();
  95 };