00001 // Copyright (C) 2007, 2008, 2009 EPITA Research and Development Laboratory (LRDE) 00002 // 00003 // This file is part of Olena. 00004 // 00005 // Olena is free software: you can redistribute it and/or modify it under 00006 // the terms of the GNU General Public License as published by the Free 00007 // Software Foundation, version 2 of the License. 00008 // 00009 // Olena is distributed in the hope that it will be useful, 00010 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00011 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00012 // General Public License for more details. 00013 // 00014 // You should have received a copy of the GNU General Public License 00015 // along with Olena. If not, see <http://www.gnu.org/licenses/>. 00016 // 00017 // As a special exception, you may use this file as part of a free 00018 // software project without restriction. Specifically, if other files 00019 // instantiate templates or use macros or inline functions from this 00020 // file, or you compile this file and link it with other files to produce 00021 // an executable, this file does not by itself cause the resulting 00022 // executable to be covered by the GNU General Public License. This 00023 // exception does not however invalidate any other reasons why the 00024 // executable file might be covered by the GNU General Public License. 00025 00026 #ifndef MLN_CORE_INTERNAL_FORCE_EXACT_HH 00027 # define MLN_CORE_INTERNAL_FORCE_EXACT_HH 00028 00031 00032 #include <cstddef> 00033 00034 00035 namespace mln 00036 { 00037 00038 namespace internal 00039 { 00040 00049 template <typename E, typename T> 00050 E& force_exact(const T& ref) 00051 { 00052 static const E* exact_obj; 00053 static const T& exact_obj_ref = *exact_obj; 00054 static const ptrdiff_t exact_offset = 00055 (const char*)(void*)(&exact_obj_ref) 00056 - (const char*)(void*)(exact_obj); 00057 return *(E*)((char*)(&ref) - exact_offset); 00058 } 00059 00060 } // end of namespace mln::internal 00061 00062 } // end of namespace mln 00063 00064 00065 #endif // ! MLN_CORE_INTERNAL_FORCE_EXACT_HH