Create akchilov3消灭一切打表式反射.cpp

src/群友提交/第10题/akchilov3消灭一切打表式反射.cpp

@@ -0,0 +1,88 @@
+ #include<iostream>
+ //打什么表，直接在构造函数里面干它丫的
+ template<class T>
+ void runtime_align_offset_advance(std::size_t& layer, std::size_t &value, const std::size_t offset)
+ {
+     const std::size_t pack_size = alignof(T);
+     const std::size_t half_pack = pack_size / 2;
+
+     if (value + offset >= pack_size){
+         const std::size_t advance_base = offset / pack_size;
+         const bool has_rest = static_cast<bool>(offset % pack_size);
+         const std::size_t advance_fix = has_rest ? advance_base + 1 : advance_base;
+
+         layer += (((offset + value == pack_size) ? 0 : (value == 0 ? 0 : 1)) + advance_fix);
+         value = 0;
+     }
+     else{
+         value = ((value + offset > half_pack && offset >= half_pack) ? pack_size : (value + offset));
+     }
+ }
+
+ template<class T> std::size_t runtime_align_offset_seek(const std::size_t pack_size, const std::size_t value, const std::size_t layer)
+ {
+     const std::size_t seek_offset = sizeof(T);
+     std::size_t seek_layer{layer}, seek_value{};
+
+     if (seek_offset + value >= pack_size){
+         if (value != 0) {
+             seek_layer += 1;
+             seek_value = 0;
+         }
+     }else {
+         seek_value = (seek_offset >= pack_size / 2) ? ((value == 0) ? 0 : (pack_size / 2)) : value;
+     }
+     return seek_layer * pack_size + seek_value;
+ }
+
+ //只要一转换就调用，构造函数会自动调用这个
+ template<class F, class TT> struct init_and_call
+ {
+     F f;
+     TT* x;
+     inline static std::size_t value = 0;
+     inline static std::size_t layer = 0;
+
+     template<class T>
+     operator T() {
+         unsigned char* base_ptr = reinterpret_cast<unsigned char*>(x);
+         const std::size_t offset = runtime_align_offset_seek<T>(alignof(TT), value, layer);
+
+         f(*(reinterpret_cast<T*>(base_ptr + offset)));
+
+         runtime_align_offset_advance<TT>(layer, value, sizeof(T));
+
+         return T{};
+     };
+ };
+//既然都不用结构化绑定了，size也不用求了吧，求了也只是重复一下上面的代码
+ template<class F, class T, class first, class ...rest> constexpr void for_each_member_impl(F f, T* x)
+ {
+     if constexpr (!requires{ T{ first{}, rest{}... }; }) {
+         T{ rest{f, x}... };
+     }
+     else {
+         for_each_member_impl<F, T, init_and_call<F, T>, first, rest...>(f, x);
+     }
+ }
+
+ template<class F, class T> constexpr void for_each_member(F f, T& x)
+ {
+     for_each_member_impl<F, T, init_and_call<F, T>>(f, &x);
+     init_and_call<F, T>::value = 0;
+     init_and_call<F, T>::layer = 0;
+ }
+
+ struct X
+ {
+    char cc{'k'};
+    int a{10};
+    char c{'l'};
+    double b{2.33};
+ };
+
+ int main()
+ {
+    X x{};
+    for_each_member([](auto a){ std::cout<<a<<' ';}, x);
+ }