Extension.h

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//=========================================================================
//  Copyright (c) Kitware, Inc.
//  All rights reserved.
//  See LICENSE.txt for details.
//
//  This software is distributed WITHOUT ANY WARRANTY; without even
//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
//  PURPOSE.  See the above copyright notice for more information.
//=========================================================================
#ifndef smtk_common_Extension_h
#define smtk_common_Extension_h
 
#include "smtk/CoreExports.h"
#include "smtk/SharedFromThis.h"
#include "smtk/common/CompilerInformation.h"
 
#ifdef SMTK_MSVC
// Ignore symbol exposure warnings for STL classes.
#pragma warning(disable : 4251)
#endif
 
#include <functional>
 
#define smtkDeclareExtension(exportmacro, name, cls)                                               \
  void exportmacro smtk_##name##_extension_AutoInit_Construct()                                    \
  {                                                                                                \
    smtk::common::Extension::registerExtension(                                                    \
      #name,                                                                                       \
      []() { return std::dynamic_pointer_cast<smtk::common::Extension>(cls::create()); },          \
      /* Never register class-static extension constructor as one-shot */ false);                  \
  }                                                                                                \
  void exportmacro smtk_##name##_extension_AutoInit_Destruct()                                     \
  {                                                                                                \
    smtk::common::Extension::unregisterExtension(#name);                                           \
  }
 
namespace smtk
{
namespace common
{
 
class SMTKCORE_EXPORT Extension : smtkEnableSharedPtr(Extension)
{
public:
  smtkTypeMacroBase(Extension);
  virtual ~Extension();
 
  static bool registerExtension(
    const std::string& name,
    std::function<Extension::Ptr(void)> ctor,
    bool oneShot = true);
 
  static bool unregisterExtension(const std::string& name);
 
  static void visitAll(
    std::function<std::pair<bool, bool>(const std::string&, Extension::Ptr)> visitor);
 
  template<typename T>
  static void visit(std::function<std::pair<bool, bool>(const std::string&, T)> visitor)
  {
    T result;
    Extension::visitAll([&result, visitor](const std::string& name, Extension::Ptr entry) {
      result = smtk::dynamic_pointer_cast<typename T::element_type>(entry);
      if (!result)
      {
        return std::make_pair(false, false);
      }
      return visitor(name, result);
    });
  }
 
  static Extension::Ptr find(const std::string& name, bool removeOneShot = true);
 
  template<typename T>
  static typename T::Ptr findAs(const std::string& name)
  {
    typename T::Ptr result = std::dynamic_pointer_cast<T>(Extension::find(name, false));
    return result;
  }
 
protected:
  Extension();
};
} // namespace common
} // namespace smtk
 
#endif