/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla IPC.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2003
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Conrad Carlen <ccarlen@netscape.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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 * the provisions above, a recipient may use your version of this file under
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 *
 * ***** END LICENSE BLOCK ***** */

#ifndef ipcMessageReader_h__
#define ipcMessageReader_h__

#include "prtypes.h"

//*****************************************************************************
// ipcMessageReader
//
// Reads from a const buffer supplied to it. Does not take ownership of the
// buffer. Bytes are read in native endianess, as ipcMessageWriter writes them
// in native endianess.
//*****************************************************************************   

class ipcMessageReader
{
public:
                  ipcMessageReader(const PRUint8* inBuffer, PRUint32 bufferSize) :
                    mBuf(inBuffer), mBufEnd(inBuffer + bufferSize),
                    mBufPtr(mBuf),
                    mError(PR_FALSE)
                  { }
                  
                  ~ipcMessageReader()
                  { }

                  // Returns PR_TRUE if an error has occured at any point
                  // during the lifetime of this object. Any read operation
                  // will safely return 0 on an error condition.
  PRBool          HasError()
                  { return mError; }
  
  PRUint8         GetInt8();
  PRUint16        GetInt16();
  PRUint32        GetInt32();
  PRInt32         GetBytes(void* destBuffer, PRInt32 n);
  
                  // Returns data at the current read position.
  const PRUint8*  GetPtr()
                  { return mBufPtr; }

                  // Returns PR_TRUE if the new position is within the buffer.
                  // Returns PR_FALSE and sets error state if not.
  PRBool          AdvancePtr(PRInt32 n);
      
private:
  const PRUint8   *mBuf, *mBufEnd;
  const PRUint8   *mBufPtr;
  PRBool          mError;
};

#endif // ipcMessageReader_h__