TObj_Persistence.hxx

// Created on: 2004-11-23
// Created by: Pavel TELKOV
// Copyright (c) 2004-2014 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.

// The original implementation Copyright: (C) RINA S.p.A

#ifndef TObj_Persistence_HeaderFile
#define TObj_Persistence_HeaderFile

#include <NCollection_DataMap.hxx>
#include <TCollection_AsciiString.hxx>
#include <TCollection_HExtendedString.hxx>
#include <TDF_Label.hxx>
#include <NCollection_Sequence.hxx>
#include <NCollection_HSequence.hxx>
class TObj_Object;

class TDF_Label;

/** This class is intended to be a root of tools (one per class)
 *   to manage persistence of objects inherited from TObj_Object
 *   It provides a mechanism to recover correctly typed
 *   objects (subtypes of TObj_Object) out of their persistent names
 *
 *   This is a special kind of object, it automatically registers itself
 *   in a global map when created, and the only thing it does is to
 *   create a new object of the type that it manages, by request
 */

class TObj_Persistence
{
public:
  /**
   * Public methods, to be called externally
   */

  //! Creates and returns a new object of the registered type
  //! If the type is not registered, returns Null handle
  static Standard_EXPORT occ::handle<TObj_Object> CreateNewObject(const char* const theType,
                                                                  const TDF_Label&  theLabel);

  //! Dumps names of all the types registered for persistence to the
  //! specified stream
  static Standard_EXPORT void DumpTypes(Standard_OStream& theOs);

protected:
  /**
   * Protected methods, to be used or defined by descendants
   */

  //! The constructor registers the object
  Standard_EXPORT TObj_Persistence(const char* const theType);

  //! The destructor unregisters the object
  virtual Standard_EXPORT ~TObj_Persistence();

  //! The method must be redefined in the derived class and return
  //! new object of the proper type
  virtual Standard_EXPORT occ::handle<TObj_Object> New(const TDF_Label& theLabel) const = 0;

  //! Dictionary storing all the registered types. It is implemented as static
  //! variable inside member function in order to ensure initialization
  //!  at first call
  static Standard_EXPORT NCollection_DataMap<TCollection_AsciiString, void*>& getMapOfTypes();

private:
  const char* myType; //!< Name of managed type (recorded for unregistering)
};

//! Declare subclass and methods of the class inherited from TObj_Object
//! necessary for implementation of persistence
//! This declaration should be put inside class declaration, under 'protected' modifier
#ifdef SOLARIS
  //! Workaround on SUN to avoid stupid warnings
  #define _TOBJOCAF_PERSISTENCE_ACCESS_ public:
#else
  #define _TOBJOCAF_PERSISTENCE_ACCESS_
#endif
#define DECLARE_TOBJOCAF_PERSISTENCE(name, ancestor)                                               \
  name(const TObj_Persistence* p, const TDF_Label& aLabel)                                         \
      : ancestor(p, aLabel)                                                                        \
  {                                                                                                \
    initFields();                                                                                  \
  } /* give the object a chance to initialize its fields */                                        \
                                                                                                   \
  /* Creates an object of a proper type */                                                         \
  /* First argument is used just to avoid possible conflict with other constructors */             \
  _TOBJOCAF_PERSISTENCE_ACCESS_                                                                    \
  class Persistence_ : public TObj_Persistence                                                     \
  {                                                                                                \
    /* Friend private class of name, is a tool providing persistence */                            \
  public:                                                                                          \
    Persistence_()                                                                                 \
        : TObj_Persistence(#name)                                                                  \
    {                                                                                              \
    } /* register the tool */                                                                      \
    virtual occ::handle<TObj_Object> New(const TDF_Label& aLabel) const;                           \
    /* Creates an object of a proper type */                                                       \
  };                                                                                               \
  friend class Persistence_;                                                                       \
  static Persistence_ myPersistence_; /* Static field implementing persistsnce tool */

//! Implement mechanism for registration the type for persistence
//! This should not be used for abstract classes (while DECLARE should)
#define IMPLEMENT_TOBJOCAF_PERSISTENCE(name)                                                       \
  name::Persistence_       name::myPersistence_;                                                   \
  occ::handle<TObj_Object> name::Persistence_::New(const TDF_Label& aLabel) const                  \
  {                                                                                                \
    return new name(static_cast<const TObj_Persistence*>(nullptr), aLabel);                        \
  }

#endif

#ifdef _MSC_VER
#pragma once
#endif