support bazel complie this project and format code.

learn_class/modern_cpp_30/smart_ptr/unique_ptr.cpp

@@ -0,0 +1,71 @@
+//
+// Created by light on 19-12-12.
+//
+
+#include "../RAII/shape.h"
+
+template <typename T> class unique_ptr {
+public:
+  explicit unique_ptr(T *ptr = nullptr) noexcept : ptr_(ptr) {}
+
+  ~unique_ptr() noexcept { delete ptr_; }
+
+  T &operator*() const noexcept { return *ptr_; }
+
+  T *operator->() const noexcept { return ptr_; }
+
+  operator bool() const noexcept { return ptr_; }
+
+  T *get() const noexcept { return ptr_; }
+
+  unique_ptr(unique_ptr &&other) noexcept {
+    cout << "move ctor" << endl;
+    ptr_ = other.release();
+  }
+
+  template <typename U> unique_ptr(unique_ptr<U> &&other) noexcept {
+    cout << "U move ctor" << endl;
+    ptr_ = other.release();
+  }
+
+  // copy and swap  始终只有一个对象有管理这块空间的权限
+  unique_ptr &operator=(unique_ptr rhs) noexcept {
+    rhs.swap(*this);
+    return *this;
+  }
+
+  // 原来的指针释放所有权
+  T *release() noexcept {
+    T *ptr = ptr_;
+    ptr_ = nullptr;
+    return ptr;
+  }
+
+  void swap(unique_ptr &rhs) noexcept {
+    using std::swap;
+    swap(ptr_, rhs.ptr_); // 转移指针所有权
+  }
+
+private:
+  T *ptr_;
+};
+
+template <typename T> void swap(unique_ptr<T> &lhs, unique_ptr<T> &rhs) {
+  lhs.swap(rhs);
+}
+
+int main() {
+  unique_ptr<shape> ptr1{create_shape(shape_type::circle)};
+  //    unique_ptr<shape> ptr2{ptr1}; // error
+  unique_ptr<shape> ptr2_2{std::move(ptr1)}; // ok
+  if (ptr2_2.get() != nullptr && ptr1.get() == nullptr)
+    ptr2_2.get()->print();
+
+  unique_ptr<shape> ptr3{create_shape(shape_type::rectangle)};
+  //    ptr1 = ptr3;    // error
+  ptr3 = std::move(ptr1); // ok
+  //    unique_ptr<circle> cl{create_shape(shape_type::circle)};  // error
+  //    因为create_shape返回的是shape 不能基类转子类
+  unique_ptr<circle> cl{new circle()};
+  unique_ptr<shape> ptr5(std::move(cl)); // ok unique<circle>转unique<circle>
+}