xpcom/io/nsISeekableStream.idl

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   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
   7 /*
   8  * nsISeekableStream
   9  *
  10  * Note that a stream might not implement all methods (e.g., a readonly stream
  11  * won't implement setEOF)
  12  */
  13
  14 #include "nsISupports.idl"
  15
  16 [scriptable, uuid(8429d350-1040-4661-8b71-f2a6ba455980)]
  17 interface nsISeekableStream : nsISupports
  18 {
  19     /*
  20      * Sets the stream pointer to the value of the 'offset' parameter
  21      */
  22     const int32_t NS_SEEK_SET = 0;
  23
  24     /*
  25      * Sets the stream pointer to its current location plus the value
  26      * of the offset parameter.
  27      */
  28     const int32_t NS_SEEK_CUR = 1;
  29
  30     /*
  31      * Sets the stream pointer to the size of the stream plus the value
  32      * of the offset parameter.
  33      */
  34     const int32_t NS_SEEK_END = 2;
  35
  36     /**
  37      *  seek
  38      *
  39      *  This method moves the stream offset of the steam implementing this
  40      *  interface.
  41      *
  42      *   @param whence specifies how to interpret the 'offset' parameter in
  43      *                 setting the stream offset associated with the implementing
  44      *                 stream.
  45      *
  46      *   @param offset specifies a value, in bytes, that is used in conjunction
  47      *                 with the 'whence' parameter to set the stream offset of the
  48      *                 implementing stream.  A negative value causes seeking in
  49      *                 the reverse direction.
  50      *
  51      *   @throws NS_BASE_STREAM_CLOSED if called on a closed stream.
  52      */
  53     void seek(in long whence, in long long offset);
  54
  55     /**
  56      *  tell
  57      *
  58      *  This method reports the current offset, in bytes, from the start of the
  59      *  stream.
  60      *
  61      *   @throws NS_BASE_STREAM_CLOSED if called on a closed stream.
  62      */
  63     long long tell();
  64
  65
  66     /**
  67      *  setEOF
  68      *
  69      *  This method truncates the stream at the current offset.
  70      *
  71      *   @throws NS_BASE_STREAM_CLOSED if called on a closed stream.
  72      */
  73     void setEOF();
  74 };