michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * nsISeekableStream
michael@0:  *
michael@0:  * Note that a stream might not implement all methods (e.g., a readonly stream 
michael@0:  * won't implement setEOF)
michael@0:  */
michael@0: 
michael@0: #include "nsISupports.idl"
michael@0: 
michael@0: [scriptable, uuid(8429d350-1040-4661-8b71-f2a6ba455980)]
michael@0: interface nsISeekableStream : nsISupports
michael@0: {
michael@0:     /* 
michael@0:      * Sets the stream pointer to the value of the 'offset' parameter 
michael@0:      */
michael@0:     const int32_t NS_SEEK_SET = 0;
michael@0: 
michael@0:     /*  
michael@0:      * Sets the stream pointer to its current location plus the value 
michael@0:      * of the offset parameter. 
michael@0:      */
michael@0:     const int32_t NS_SEEK_CUR = 1;
michael@0: 
michael@0:     /* 
michael@0:      * Sets the stream pointer to the size of the stream plus the value 
michael@0:      * of the offset parameter. 
michael@0:      */
michael@0:     const int32_t NS_SEEK_END = 2;
michael@0: 
michael@0:     /**
michael@0:      *  seek
michael@0:      *
michael@0:      *  This method moves the stream offset of the steam implementing this
michael@0:      *  interface.
michael@0:      *
michael@0:      *   @param whence specifies how to interpret the 'offset' parameter in
michael@0:      *                 setting the stream offset associated with the implementing
michael@0:      *                 stream.
michael@0:      *     
michael@0:      *   @param offset specifies a value, in bytes, that is used in conjunction
michael@0:      *                 with the 'whence' parameter to set the stream offset of the 
michael@0:      *                 implementing stream.  A negative value causes seeking in 
michael@0:      *                 the reverse direction.
michael@0:      *
michael@0:      *   @throws NS_BASE_STREAM_CLOSED if called on a closed stream.
michael@0:      */
michael@0:     void seek(in long whence, in long long offset);
michael@0: 
michael@0:     /**
michael@0:      *  tell
michael@0:      *
michael@0:      *  This method reports the current offset, in bytes, from the start of the 
michael@0:      *  stream. 
michael@0:      *
michael@0:      *   @throws NS_BASE_STREAM_CLOSED if called on a closed stream.
michael@0:      */
michael@0:     long long tell();
michael@0: 
michael@0: 
michael@0:     /**
michael@0:      *  setEOF
michael@0:      *
michael@0:      *  This method truncates the stream at the current offset.
michael@0:      *
michael@0:      *   @throws NS_BASE_STREAM_CLOSED if called on a closed stream.
michael@0:      */
michael@0:     void setEOF();
michael@0: };