00001 // This file is a part of Catsfoot. 00002 // Copyright (C) 2011 Uni Research 00003 // 00004 // This program is free software: you can redistribute it and/or modify 00005 // it under the terms of the GNU Lesser Public License as published by 00006 // the Free Software Foundation, either version 3 of the License, or 00007 // (at your option) any later version. 00008 // 00009 // This program 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 00012 // GNU Lesser Public License for more details. 00013 // 00014 // You should have received a copy of the GNU Lesser Public License 00015 // along with this program. If not, see <http://www.gnu.org/licenses/>. 00016 00017 #ifndef HAS_REQUIREMENTS_HH 00018 # define HAS_REQUIREMENTS_HH 00019 00020 # include "../type_traits/try_first.hh" 00021 # include "../type_traits/identity.hh" 00022 00023 namespace catsfoot { 00024 00025 namespace details { 00026 template <typename T, typename = typename T::requirements> 00027 std::true_type has_requirements_helper(try_first, T&&) { 00028 static_assert(always_false<T>::value, 00029 "Cannot use this function"); 00030 return 0; 00031 } 00032 00033 template <typename T> 00034 std::false_type has_requirements_helper(try_second, T&&) { 00035 static_assert(always_false<T>::value, 00036 "Cannot use this function"); 00037 return 0; 00038 } 00039 00041 template <typename T> 00042 struct has_requirements: 00043 public identity< 00044 decltype(has_requirements_helper(try_first(), 00045 std::declval<T>()))>::type 00046 { 00047 }; 00048 00049 } 00050 00051 } 00052 00053 #endif