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lean cpp library
A lean C++ library providing efficient utility classes for high-performance C++ applications.
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00001 /*****************************************************/ 00002 /* lean Meta (c) Tobias Zirr 2011 */ 00003 /*****************************************************/ 00004 00005 #ifndef LEAN_META_TYPE_TRAITS 00006 #define LEAN_META_TYPE_TRAITS 00007 00008 namespace lean 00009 { 00010 namespace meta 00011 { 00012 00014 template <class Type1, class Type2> 00015 struct is_equal 00016 { 00018 static const bool value = false; 00019 }; 00020 00021 #ifndef DOXYGEN_SKIP_THIS 00022 00023 template <class Type> 00024 struct is_equal<Type, Type> 00025 { 00026 static const bool value = true; 00027 }; 00028 00029 #endif 00030 00032 template <class Integer> 00033 struct is_unsigned 00034 { 00035 static const Integer min = Integer(0); 00036 static const Integer max = Integer(-1); 00037 00039 static const bool value = (max > min); 00040 }; 00041 00043 template <class Type, class Base> 00044 struct is_derived 00045 { 00046 private: 00047 typedef char yes[1]; 00048 typedef char no[2]; 00049 00050 static yes& sfinae_check(Base*); 00051 static no& sfinae_check(void*); 00052 00053 public: 00055 static const bool value = ( 00056 sizeof( is_derived::sfinae_check( static_cast<Type*>(nullptr) ) ) 00057 == 00058 sizeof(yes) ); 00059 }; 00060 00061 } // namespace 00062 00063 using meta::is_equal; 00064 using meta::is_unsigned; 00065 using meta::is_derived; 00066 00068 #define LEAN_DEFINE_HAS_TYPE(TypeName) \ 00069 template <class Type> \ 00070 class has_type_##TypeName \ 00071 { \ 00072 private: \ 00073 typedef char yes[1]; \ 00074 typedef char no[2]; \ 00075 \ 00076 template <class T> \ 00077 static yes& sfinae_check(T*, typename T::TypeName* = nullptr); \ 00078 static no& sfinae_check(...); \ 00079 \ 00080 public: \ 00081 static const bool value = \ 00082 sizeof( has_type_##TypeName::sfinae_check( static_cast<Type*>(nullptr) ) ) \ 00083 == \ 00084 sizeof(yes); \ 00085 }; 00086 00087 } // namespace 00088 00089 #endif
1.7.6.1