support bazel complie this project and format code.

design_pattern/singleton/dcl_singleton.cpp

@@ -9,35 +9,35 @@ using namespace std;
 
 class singleton {
 private:
-    singleton() {}
+  singleton() {}
+
+  static singleton *p;
+  static mutex lock_;
 
-    static singleton *p;
-    static mutex lock_;
 public:
-    static singleton *instance();
+  static singleton *instance();
 
-    // 实现一个内嵌垃圾回收类
-    class CGarbo
-    {
-    public:
-        ~CGarbo()
-        {
-            if(singleton::p)
-                delete singleton::p;
-        }
-    };
-    static CGarbo Garbo; // 定义一个静态成员变量，程序结束时，系统会自动调用它的析构函数从而释放单例对象
+  // 实现一个内嵌垃圾回收类
+  class CGarbo {
+  public:
+    ~CGarbo() {
+      if (singleton::p)
+        delete singleton::p;
+    }
+  };
+  static CGarbo
+      Garbo; // 定义一个静态成员变量，程序结束时，系统会自动调用它的析构函数从而释放单例对象
 };
 
 singleton *singleton::p = nullptr;
 singleton::CGarbo Garbo;
 std::mutex singleton::lock_;
 
-singleton* singleton::instance() {
-    if (p == nullptr) {
-        lock_guard<mutex> guard(lock_);
-        if (p == nullptr)
-            p = new singleton();
-    }
-    return p;
+singleton *singleton::instance() {
+  if (p == nullptr) {
+    lock_guard<mutex> guard(lock_);
+    if (p == nullptr)
+      p = new singleton();
+  }
+  return p;
 }