Modernize ref_counted.h

base/memory/ref_counted.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_MEMORY_REF_COUNTED_H_
 #define BASE_MEMORY_REF_COUNTED_H_
 
 #include <stddef.h>
 
 #include <cassert>
 #include <iosfwd>
 #include <type_traits>
 
 #include "base/atomic_ref_count.h"
 #include "base/base_export.h"
 #include "base/compiler_specific.h"
+#include "base/logging.h"
 #include "base/macros.h"
-#ifndef NDEBUG
-#include "base/logging.h"
-#endif
 #include "base/threading/thread_collision_warner.h"
 #include "build/build_config.h"
 
 namespace base {
 
 namespace subtle {
 
 class BASE_EXPORT RefCountedBase {
  public:
   bool HasOneRef() const { return ref_count_ == 1; }
 
  protected:
   RefCountedBase()
       : ref_count_(0)
-  #ifndef NDEBUG
+#if DCHECK_IS_ON()
       , in_dtor_(false)
-  #endif
+#endif
       {
   }
 
   ~RefCountedBase() {
-  #ifndef NDEBUG
+#if DCHECK_IS_ON()
     DCHECK(in_dtor_) << "RefCounted object deleted without calling Release()";
-  #endif
+#endif
   }
 
 
   void AddRef() const {
     // TODO(maruel): Add back once it doesn't assert 500 times/sec.
     // Current thread books the critical section "AddRelease"
     // without release it.
     // DFAKE_SCOPED_LOCK_THREAD_LOCKED(add_release_);
-  #ifndef NDEBUG
+#if DCHECK_IS_ON()
     DCHECK(!in_dtor_);
-  #endif
+#endif
     ++ref_count_;
   }
 
   // Returns true if the object should self-delete.
   bool Release() const {
     // TODO(maruel): Add back once it doesn't assert 500 times/sec.
     // Current thread books the critical section "AddRelease"
     // without release it.
     // DFAKE_SCOPED_LOCK_THREAD_LOCKED(add_release_);
-  #ifndef NDEBUG
+#if DCHECK_IS_ON()
     DCHECK(!in_dtor_);
-  #endif
+#endif
     if (--ref_count_ == 0) {
-  #ifndef NDEBUG
+#if DCHECK_IS_ON()
       in_dtor_ = true;
-  #endif
+#endif
       return true;
     }
     return false;
   }
 
  private:
   mutable size_t ref_count_;
-#ifndef NDEBUG
+#if DCHECK_IS_ON()
   mutable bool in_dtor_;
 #endif
 
   DFAKE_MUTEX(add_release_);
 
   DISALLOW_COPY_AND_ASSIGN(RefCountedBase);
 };
 
 class BASE_EXPORT RefCountedThreadSafeBase {
  public:
   bool HasOneRef() const;
 
  protected:
   RefCountedThreadSafeBase();
   ~RefCountedThreadSafeBase();
 
   void AddRef() const;
 
   // Returns true if the object should self-delete.
   bool Release() const;
 
  private:
   mutable AtomicRefCount ref_count_;
-#ifndef NDEBUG
+#if DCHECK_IS_ON()
   mutable bool in_dtor_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafeBase);
 };
 
 }  // namespace subtle
 
 //
 // A base class for reference counted classes.  Otherwise, known as a cheap
 // knock-off of WebKit's RefCounted<T> class.  To use this, just extend your
 // class from it like so:
 //
 //   class MyFoo : public base::RefCounted<MyFoo> {
 //    ...
 //    private:
 //     friend class base::RefCounted<MyFoo>;
 //     ~MyFoo();
 //   };
 //
 // You should always make your destructor non-public, to avoid any code deleting
 // the object accidently while there are references to it.
 template <class T>
 class RefCounted : public subtle::RefCountedBase {
  public:
-  RefCounted() {}
+  RefCounted() = default;
 
   void AddRef() const {
     subtle::RefCountedBase::AddRef();
   }
 
   void Release() const {
     if (subtle::RefCountedBase::Release()) {
       delete static_cast<const T*>(this);
     }
   }
 
  protected:
-  ~RefCounted() {}
+  ~RefCounted() = default;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(RefCounted<T>);
 };
 
 // Forward declaration.
 template <class T, typename Traits> class RefCountedThreadSafe;
 
 // Default traits for RefCountedThreadSafe<T>.  Deletes the object when its ref
 // count reaches 0.  Overload to delete it on a different thread etc.
@@ skipping 16 matching lines @@
 //   };
 //
 // If you're using the default trait, then you should add compile time
 // asserts that no one else is deleting your object.  i.e.
 //    private:
 //     friend class base::RefCountedThreadSafe<MyFoo>;
 //     ~MyFoo();
 template <class T, typename Traits = DefaultRefCountedThreadSafeTraits<T> >
 class RefCountedThreadSafe : public subtle::RefCountedThreadSafeBase {
  public:
-  RefCountedThreadSafe() {}
+  RefCountedThreadSafe() = default;
 
   void AddRef() const {
     subtle::RefCountedThreadSafeBase::AddRef();
   }
 
   void Release() const {
     if (subtle::RefCountedThreadSafeBase::Release()) {
       Traits::Destruct(static_cast<const T*>(this));
     }
   }
 
  protected:
-  ~RefCountedThreadSafe() {}
+  ~RefCountedThreadSafe() = default;
 
  private:
   friend struct DefaultRefCountedThreadSafeTraits<T>;
   static void DeleteInternal(const T* x) { delete x; }
 
   DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafe);
 };
 
 //
 // A thread-safe wrapper for some piece of data so we can place other
 // things in scoped_refptrs<>.
 //
 template<typename T>
 class RefCountedData
     : public base::RefCountedThreadSafe< base::RefCountedData<T> > {
  public:
   RefCountedData() : data() {}
   RefCountedData(const T& in_value) : data(in_value) {}
 
   T data;
 
  private:
   friend class base::RefCountedThreadSafe<base::RefCountedData<T> >;
-  ~RefCountedData() {}
+  ~RefCountedData() = default;
 };
 
 }  // namespace base
 
 //
 // A smart pointer class for reference counted objects.  Use this class instead
 // of calling AddRef and Release manually on a reference counted object to
 // avoid common memory leaks caused by forgetting to Release an object
 // reference.  Sample usage:
 //
 //   class MyFoo : public RefCounted<MyFoo> {
 //    ...
 //   };
 //
 //   void some_function() {
 //     scoped_refptr<MyFoo> foo = new MyFoo();
 //     foo->Method(param);
 //     // |foo| is released when this function returns
 //   }
 //
 //   void some_other_function() {
 //     scoped_refptr<MyFoo> foo = new MyFoo();
 //     ...
-//     foo = NULL;  // explicitly releases |foo|
+//     foo = nullptr;  // explicitly releases |foo|
 //     ...
 //     if (foo)
 //       foo->Method(param);
 //   }
 //
 // The above examples show how scoped_refptr<T> acts like a pointer to T.
 // Given two scoped_refptr<T> classes, it is also possible to exchange
 // references between the two objects, like so:
 //
 //   {
 //     scoped_refptr<MyFoo> a = new MyFoo();
 //     scoped_refptr<MyFoo> b;
 //
 //     b.swap(a);
-//     // now, |b| references the MyFoo object, and |a| references NULL.
+//     // now, |b| references the MyFoo object, and |a| references nullptr.
 //   }
 //
 // To make both |a| and |b| in the above example reference the same MyFoo
 // object, simply use the assignment operator:
 //
 //   {
 //     scoped_refptr<MyFoo> a = new MyFoo();
 //     scoped_refptr<MyFoo> b;
 //
 //     b = a;
 //     // now, |a| and |b| each own a reference to the same MyFoo object.
 //   }
 //
 template <class T>
 class scoped_refptr {
  public:
   typedef T element_type;
 
-  scoped_refptr() : ptr_(NULL) {
+  scoped_refptr() : ptr_(nullptr) {
   }
 
   scoped_refptr(T* p) : ptr_(p) {
     if (ptr_)
       AddRef(ptr_);
   }
 
   // Copy constructor.
   scoped_refptr(const scoped_refptr<T>& r) : ptr_(r.ptr_) {
     if (ptr_)
@@ skipping 22 matching lines @@
   }
 
   ~scoped_refptr() {
     if (ptr_)
       Release(ptr_);
   }
 
   T* get() const { return ptr_; }
 
   T& operator*() const {
-    assert(ptr_ != NULL);
+    assert(ptr_ != nullptr);
     return *ptr_;
   }
 
   T* operator->() const {
-    assert(ptr_ != NULL);
+    assert(ptr_ != nullptr);
     return ptr_;
   }
 
   scoped_refptr<T>& operator=(T* p) {
     // AddRef first so that self assignment should work
     if (p)
       AddRef(p);
     T* old_ptr = ptr_;
     ptr_ = p;
     if (old_ptr)
@@ skipping 120 matching lines @@
 bool operator!=(std::nullptr_t null, const scoped_refptr<T>& rhs) {
   return !operator==(null, rhs);
 }
 
 template <typename T>
 std::ostream& operator<<(std::ostream& out, const scoped_refptr<T>& p) {
   return out << p.get();
 }
 
 #endif  // BASE_MEMORY_REF_COUNTED_H_