support bazel complie this project and format code.

learn_class/modern_cpp_30/compilercompute/WhileLoop.cpp

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+//
+// Created by light on 20-1-5.
+//
+
+#include <iostream>
+
+using namespace std;
+
+// 使用template实现while循环
+
+template <bool condition, typename Body> struct WhileLoop;
+
+template <typename Body> struct WhileLoop<true, Body> {
+  typedef
+      typename WhileLoop<Body::cond_value, typename Body::next_type>::type type;
+};
+
+template <typename Body> struct WhileLoop<false, Body> {
+  typedef typename Body::res_type type;
+};
+
+template <typename Body> struct While {
+  typedef typename WhileLoop<Body::cond_value, Body>::type type;
+};
+template <typename Body> using While_t = WhileLoop<Body::cond_value, Body>;
+
+namespace my {
+template <class T, T v> struct integral_constant {
+  static const T value = v;
+  typedef T value_type;
+  typedef integral_constant<T, v> type;
+};
+} // namespace my
+template <int result, int n> struct SumLoop {
+
+  // 循环的条件
+  static const bool cond_value = n != 0;
+
+  // 循环后的结果
+  static const int res_value = result;
+
+  // 循环时的状态
+  typedef my::integral_constant<int, res_value> res_type;
+
+  // 循环执行一次时的状态
+  typedef SumLoop<result + n, n - 1> next_type;
+};
+
+template <int n> struct Sum { typedef SumLoop<0, n> type; };
+
+template <int n> using Sum_t = SumLoop<0, n>;
+
+int main() {
+  cout << While<Sum<6>::type>::type::value << endl;
+  cout << While_t<Sum_t<6>>::type::value << endl;
+  return 0;
+}