/*=========================================================================

  Program:   KWSys - Kitware System Library
  Module:    $RCSfile: DynamicLoader.hxx.in,v $

  Copyright (c) Kitware, Inc., Insight Consortium.  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm 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 notices for more information.

=========================================================================*/
#ifndef itksys_DynamicLoader_hxx
#define itksys_DynamicLoader_hxx

#include <itksys/Configure.h>

#if defined(__hpux)
  #include <dl.h>
#elif defined(_WIN32)
  #include <windows.h>
#elif defined(__APPLE__)
  #include <AvailabilityMacros.h>
  #if MAC_OS_X_VERSION_MIN_REQUIRED < 1030
    #include <mach-o/dyld.h>
  #endif
#endif

namespace itksys
{
/** \class DynamicLoader
 * \brief Portable loading of dynamic libraries or dll's.
 *
 * DynamicLoader provides a portable interface to loading dynamic
 * libraries or dll's into a process.
 *
 * Directory currently works with Windows, Apple, HP-UX and Unix (POSIX)
 * operating systems
 *
 * \warning dlopen on *nix system works the following way:
 * If filename contains a slash ("/"), then it is interpreted as a (relative
 * or absolute) pathname.  Otherwise, the dynamic linker searches for the
 * library as follows : see ld.so(8) for further details):
 * Whereas this distinction does not exist on Win32. Therefore ideally you
 * should be doing full path to garantee to have a consistent way of dealing
 * with dynamic loading of shared library.
 */

class itksys_EXPORT DynamicLoader
{
public:
// Ugly stuff for library handles
// They are different on several different OS's
#if defined(__hpux)
  typedef shl_t LibraryHandle;
#elif defined(_WIN32)
  typedef HMODULE LibraryHandle;
#elif defined(__APPLE__)
  #if MAC_OS_X_VERSION_MIN_REQUIRED < 1030
    typedef NSModule LibraryHandle;
  #else
    typedef void* LibraryHandle;
  #endif
#else
  typedef void* LibraryHandle;
#endif

  // Return type from DynamicLoader::GetSymbolAddress.
  typedef void (*SymbolPointer)();

  DynamicLoader();
  ~DynamicLoader();

  /** Load a dynamic library into the current process.
   * The returned LibraryHandle can be used to access the symbols in the
   * library. */
  static LibraryHandle OpenLibrary(const char*);

  /** Attempt to detach a dynamic library from the
   * process.  A value of true is returned if it is sucessful. */
  static int CloseLibrary(LibraryHandle);

  /** Find the address of the symbol in the given library. */
  static SymbolPointer GetSymbolAddress(LibraryHandle, const char*);

  /** Return the library prefix for the given architecture */
  static const char* LibPrefix();

  /** Return the library extension for the given architecture. */
  static const char* LibExtension();

  /** Return the last error produced from a calls made on this class. */
  static const char* LastError();
}; // End Class: DynamicLoader

} // namespace itksys

#endif
