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[occt.git] / src / StdStorage / StdStorage.hxx

// Copyright (c) 2017 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#ifndef _StdStorage_HeaderFile
#define _StdStorage_HeaderFile

#include <Standard_Macro.hxx>
#include <Storage_Error.hxx>
class StdStorage_Data;
class Storage_BaseDriver;
class TCollection_AsciiString;

//! StdStorage package is used to write and read persistent objects.
//! These objects are read and written by a retrieval or storage
//! algorithm (compatible with legacy Storage_Schema) in a container 
//! (disk, memory, network ...). Drivers (FSD_File objects) assign a physical
//! container for data to be stored or retrieved.
//! The standard procedure for an application in reading a container is 
//!  to call one of the Read functions providing either a file path or a driver 
//! opened for reading. Thes function update the instance of the StdStorage_Data 
//! class which contains the data being read.
//! The standard procedure for an application in writing a container is the following:
//! -   open the driver in writing mode,
//! -   create an instance of the StdStorage_Data class, then
//! add the persistent data to write with the function AddRoot,
//! -   call the function Write from the storage, setting the driver and the 
//! Storage_Data instance as parameters,
//! -   close the driver.
class StdStorage
{

public:

  //! Returns the version of Storage's read/write routines
  Standard_EXPORT static TCollection_AsciiString Version();

  //! Returns the data read from a file located at theFileName. 
  //! The storage format is compartible with legacy persistent one.
  //! These data are aggregated in a StdStorage_Data object which may be 
  //! browsed in order to extract the root objects from the container.
  //! Note: - theData object will be created if it is null or cleared otherwise.
  Standard_EXPORT static Storage_Error Read(const TCollection_AsciiString& theFileName,
                                            Handle(StdStorage_Data)&       theData);

  //! Returns the data read from the container defined by theDriver. 
  //! The storage format is compartible with legacy persistent one.
  //! These data are aggregated in a StdStorage_Data object which may be 
  //! browsed in order to extract the root objects from the container.
  //! Note: - theData object will be created if it is null or cleared otherwise.
  Standard_EXPORT static Storage_Error Read(const Handle(Storage_BaseDriver)& theDriver,
                                            Handle(StdStorage_Data)& theData);

  //! Writes the data aggregated in theData object into the container defined by 
  //! theDriver. The storage format is compartible with legacy persistent one.
  //! Note: - theData may aggregate several root objects to be stored together.
  //!       - createion date specified in the srorage header will be overwritten.
  Standard_EXPORT static Storage_Error Write(const Handle(Storage_BaseDriver)& theDriver,
                                             const Handle(StdStorage_Data)& theData);

};

#endif // _StdStorage_HeaderFile