CMemoryStream.h

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/* +---------------------------------------------------------------------------+
   |          The Mobile Robot Programming Toolkit (MRPT) C++ library          |
   |                                                                           |
   |                       http://www.mrpt.org/                                |
   |                                                                           |
   |   Copyright (C) 2005-2011  University of Malaga                           |
   |                                                                           |
   |    This software was written by the Machine Perception and Intelligent    |
   |      Robotics Lab, University of Malaga (Spain).                          |
   |    Contact: Jose-Luis Blanco  <jlblanco@ctima.uma.es>                     |
   |                                                                           |
   |  This file is part of the MRPT project.                                   |
   |                                                                           |
   |     MRPT is free software: you can redistribute it and/or modify          |
   |     it under the terms of the GNU General Public License as published by  |
   |     the Free Software Foundation, either version 3 of the License, or     |
   |     (at your option) any later version.                                   |
   |                                                                           |
   |   MRPT is distributed in the hope that it will be useful,                 |
   |     but WITHOUT ANY WARRANTY; without even the implied warranty of        |
   |     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         |
   |     GNU General Public License for more details.                          |
   |                                                                           |
   |     You should have received a copy of the GNU General Public License     |
   |     along with MRPT.  If not, see <http://www.gnu.org/licenses/>.         |
   |                                                                           |
   +---------------------------------------------------------------------------+ */
#ifndef  CMEMORYSTREAM_H
#define  CMEMORYSTREAM_H

#include <mrpt/utils/CStream.h>
#include <mrpt/utils/safe_pointers.h>

/*---------------------------------------------------------------
        Class
  ---------------------------------------------------------------*/
namespace mrpt
{
namespace utils
{
        /** This CStream derived class allow using a memory buffer as a CStream.
         *  This class is useful for storing any required set of variables or objects,
         *   and then read them to other objects, or storing them to a file, for example.
         *
         * \sa CStream
         * \ingroup mrpt_base_grp
         */
        class BASE_IMPEXP CMemoryStream : public CStream
        {
        protected:
                 /** Method responsible for reading from the stream.
                 */
                size_t Read(void *Buffer, size_t Count);

                /** Method responsible for writing to the stream.
                 *  Write attempts to write up to Count bytes to Buffer, and returns the number of bytes actually written.
                 */
                size_t Write(const void *Buffer, size_t Count);

                /** Internal data
                 */
                void_ptr_noncopy        m_memory;
                uint64_t        m_size, m_position, m_bytesWritten;
                uint64_t        m_alloc_block_size;
                bool    m_read_only;   //!< If the memory block does not belong to the object.

                /** Resizes the internal buffer size.
                 */
                void resize(uint64_t newSize);
        public:
                /** Default constructor
                 */
                CMemoryStream();

                /** Constructor to initilize the data in the stream from a block of memory (which is copied), and sets the current stream position at the beginning of the data.
                 * \sa assignMemoryNotOwn
                 */
                CMemoryStream( const void *data, const uint64_t nBytesInData );

                /** Initilize the data in the stream from a block of memory which is NEITHER OWNED NOR COPIED by the object, so it must exist during the whole live of the object.
                  *  After assigning a block of data with this method, the object becomes "read-only", so further attempts to change the size of the buffer will raise an exception.
                  *  This method resets the write and read positions to the beginning.
                  */
                void assignMemoryNotOwn( const void *data, const uint64_t nBytesInData );

                /** Destructor
                 */
                virtual ~CMemoryStream();

                /** Clears the memory buffer.
                 */
                void  Clear();

                /** Change size. This would be rarely used. Use ">>" operators for writing to stream.
                 * \sa Stream
                 */
                void  changeSize( uint64_t newSize );

                /** Method for moving to a specified position in the streamed resource.
                 *  \sa CStream::Seek
                 */
                uint64_t Seek(long Offset, CStream::TSeekOrigin Origin = sFromBeginning);

                /** Returns the total size of the internal buffer.
                 */
                uint64_t getTotalBytesCount();

                /** Method for getting the current cursor position, where 0 is the first byte and TotalBytesCount-1 the last one.
                 */
                uint64_t getPosition();

                /** Method for getting a pointer to the raw stored data.
                 * The lenght in bytes is given by getTotalBytesCount
                 */
                void*  getRawBufferData();


                /** Saves the entire buffer to a file
                  * \return true on success, false on error
                  */
                bool saveBufferToFile( const std::string &file_name );

                /** Loads the entire buffer from a file
                  * \return true on success, false on error
                  */
                bool loadBufferFromFile( const std::string &file_name );

                /** Change the size of the additional memory block that is reserved whenever the current block runs too short (default=0x10000 bytes) */
                void setAllocBlockSize( uint64_t  alloc_block_size )
                {
                        ASSERT_(alloc_block_size>0)
                        m_alloc_block_size = alloc_block_size;
                }

        }; // End of class def.

        } // End of namespace
} // end of namespace
#endif