这是博客开通前几天做的，C++的模板没办法存方便的浮点数，算了。
基本类型的设计参考了vczh轮子叔模仿boost的MPL的设计。
话说template和typename写多了真是无限烦人啊，不得已定义了几个宏，然后运算的定义也是用宏批量生成的。
1 template<typename TPOD, TPOD V> 2 struct PODType 3 { 4 static const TPOD Value = V; 5 using Type = TPOD; 6 using Self = PODType<TPOD, V>; 7 }; 8 9 template<int VInt> 10 using Int = PODType<int, VInt>; 11 12 template<bool VBool> 13 using Bool = PODType<bool, VBool>; 14 15 template<char VChar> 16 using Char = PODType<char, VChar>; 17 18 #define TN typename 19 #define TT template 20 #define SS struct 21 22 #define DEFINE_BIN_META_OPERATION_HEAD(Name) 23 TT<TN T1, TN T2> 24 SS Name 25 26 #define DEFINE_BIN_META_OPERATION_BODY(Name, TType, VType, RType, op) 27 TT<VType V1, VType V2> 28 SS Name<TType<V1>, TType<V2>> 29 { 30 using Result = TN RType<(V1 op V2)>; 31 } 32 33 #define DEFINE_UNA_META_OPERATION_HEAD(Name) 34 TT<TN T1> 35 SS Name 36 37 #define DEFINE_UNA_META_OPERATION_BODY(Name, TType, VType, RType, op) 38 TT<VType V1> 39 SS Name<TType<V1>> 40 { 41 using Result = TN RType<(op V1)>; 42 } 43 44 DEFINE_BIN_META_OPERATION_HEAD(Add); 45 DEFINE_BIN_META_OPERATION_BODY(Add, Int, int, Int, +); 46 DEFINE_BIN_META_OPERATION_BODY(Add, Char, char, Char, +); 47 DEFINE_BIN_META_OPERATION_HEAD(Sub); 48 DEFINE_BIN_META_OPERATION_BODY(Sub, Int, int, Int, -); 49 DEFINE_BIN_META_OPERATION_BODY(Sub, Char, char, Char, -); 50 DEFINE_BIN_META_OPERATION_HEAD(Mul); 51 DEFINE_BIN_META_OPERATION_BODY(Mul, Int, int, Int, *); 52 DEFINE_BIN_META_OPERATION_BODY(Mul, Char, char, Char, *); 53 DEFINE_BIN_META_OPERATION_HEAD(Div); 54 DEFINE_BIN_META_OPERATION_BODY(Div, Int, int, Int, / ); 55 DEFINE_BIN_META_OPERATION_BODY(Div, Char, char, Char, / ); 56 DEFINE_BIN_META_OPERATION_HEAD(Mod); 57 DEFINE_BIN_META_OPERATION_BODY(Mod, Int, int, Int, %); 58 DEFINE_BIN_META_OPERATION_BODY(Mod, Char, char, Char, %); 59 DEFINE_BIN_META_OPERATION_HEAD(And); 60 DEFINE_BIN_META_OPERATION_BODY(And, Bool, bool, Bool, &&); 61 DEFINE_BIN_META_OPERATION_HEAD(Or); 62 DEFINE_BIN_META_OPERATION_BODY(Or, Bool, bool, Bool, || ); 63 DEFINE_BIN_META_OPERATION_HEAD(Xor); 64 DEFINE_BIN_META_OPERATION_BODY(Xor, Bool, bool, Bool, ^); 65 DEFINE_BIN_META_OPERATION_HEAD(Eq); 66 DEFINE_BIN_META_OPERATION_BODY(Eq, Bool, bool, Bool, == ); 67 DEFINE_BIN_META_OPERATION_BODY(Eq, Int, int, Bool, == ); 68 DEFINE_BIN_META_OPERATION_BODY(Eq, Char, char, Bool, == ); 69 DEFINE_BIN_META_OPERATION_HEAD(Neq); 70 DEFINE_BIN_META_OPERATION_BODY(Neq, Bool, bool, Bool, != ); 71 DEFINE_BIN_META_OPERATION_BODY(Neq, Int, int, Bool, != ); 72 DEFINE_BIN_META_OPERATION_BODY(Neq, Char, char, Bool, != ); 73 DEFINE_BIN_META_OPERATION_HEAD(Gt); 74 DEFINE_BIN_META_OPERATION_BODY(Gt, Int, int, Bool, > ); 75 DEFINE_BIN_META_OPERATION_BODY(Gt, Char, char, Bool, > ); 76 DEFINE_BIN_META_OPERATION_HEAD(Lt); 77 DEFINE_BIN_META_OPERATION_BODY(Lt, Int, int, Bool, < ); 78 DEFINE_BIN_META_OPERATION_BODY(Lt, Char, char, Bool, < ); 79 DEFINE_BIN_META_OPERATION_HEAD(Ge); 80 DEFINE_BIN_META_OPERATION_BODY(Ge, Int, int, Bool, >= ); 81 DEFINE_BIN_META_OPERATION_BODY(Ge, Char, char, Bool, >= ); 82 DEFINE_BIN_META_OPERATION_HEAD(Le); 83 DEFINE_BIN_META_OPERATION_BODY(Le, Int, int, Bool, <= ); 84 DEFINE_BIN_META_OPERATION_BODY(Le, Char, char, Bool, <= ); 85 DEFINE_UNA_META_OPERATION_HEAD(Neg); 86 DEFINE_UNA_META_OPERATION_BODY(Neg, Int, int, Int, -); 87 DEFINE_UNA_META_OPERATION_BODY(Neg, Char, char, Char, -); 88 DEFINE_UNA_META_OPERATION_HEAD(Not); 89 DEFINE_UNA_META_OPERATION_BODY(Not, Bool, bool, Bool, !);
使用起来是这样的
1 Int<1> a; 2 Int<2> b; 3 Add<decltype(a), decltype(b)>::Result aplusb; 4 Sub<decltype(a), decltype(b)>::Result aminusb; 5 6 Bool<false> b1; 7 Bool<true> b2; 8 And<decltype(b1), decltype(b2)>::Result b1andb2;
可以从vs2015的intellisense很清楚得看到运算结果
就这样