| // Copyright 2014 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_MAC_SCOPED_TYPEREF_H_ |
| #define BASE_MAC_SCOPED_TYPEREF_H_ |
| |
| #include "base/basictypes.h" |
| #include "base/compiler_specific.h" |
| #include "base/logging.h" |
| #include "base/memory/scoped_policy.h" |
| |
| namespace base { |
| |
| // ScopedTypeRef<> is patterned after scoped_ptr<>, but maintains a ownership |
| // of a reference to any type that is maintained by Retain and Release methods. |
| // |
| // The Traits structure must provide the Retain and Release methods for type T. |
| // A default ScopedTypeRefTraits is used but not defined, and should be defined |
| // for each type to use this interface. For example, an appropriate definition |
| // of ScopedTypeRefTraits for CGLContextObj would be: |
| // |
| // template<> |
| // struct ScopedTypeRefTraits<CGLContextObj> { |
| // void Retain(CGLContextObj object) { CGLContextRetain(object); } |
| // void Release(CGLContextObj object) { CGLContextRelease(object); } |
| // }; |
| // |
| // For the many types that have pass-by-pointer create functions, the function |
| // InitializeInto() is provided to allow direct initialization and assumption |
| // of ownership of the object. For example, continuing to use the above |
| // CGLContextObj specialization: |
| // |
| // base::ScopedTypeRef<CGLContextObj> context; |
| // CGLCreateContext(pixel_format, share_group, context.InitializeInto()); |
| // |
| // For initialization with an existing object, the caller may specify whether |
| // the ScopedTypeRef<> being initialized is assuming the caller's existing |
| // ownership of the object (and should not call Retain in initialization) or if |
| // it should not assume this ownership and must create its own (by calling |
| // Retain in initialization). This behavior is based on the |policy| parameter, |
| // with |ASSUME| for the former and |RETAIN| for the latter. The default policy |
| // is to |ASSUME|. |
| |
| template<typename T> |
| struct ScopedTypeRefTraits; |
| |
| template<typename T, typename Traits = ScopedTypeRefTraits<T>> |
| class ScopedTypeRef { |
| public: |
| typedef T element_type; |
| |
| ScopedTypeRef( |
| T object = NULL, |
| base::scoped_policy::OwnershipPolicy policy = base::scoped_policy::ASSUME) |
| : object_(object) { |
| if (object_ && policy == base::scoped_policy::RETAIN) |
| Traits::Retain(object_); |
| } |
| |
| ScopedTypeRef(const ScopedTypeRef<T, Traits>& that) |
| : object_(that.object_) { |
| if (object_) |
| Traits::Retain(object_); |
| } |
| |
| ~ScopedTypeRef() { |
| if (object_) |
| Traits::Release(object_); |
| } |
| |
| ScopedTypeRef& operator=(const ScopedTypeRef<T, Traits>& that) { |
| reset(that.get(), base::scoped_policy::RETAIN); |
| return *this; |
| } |
| |
| // This is to be used only to take ownership of objects that are created |
| // by pass-by-pointer create functions. To enforce this, require that the |
| // object be reset to NULL before this may be used. |
| T* InitializeInto() WARN_UNUSED_RESULT { |
| DCHECK(!object_); |
| return &object_; |
| } |
| |
| void reset(T object = NULL, |
| base::scoped_policy::OwnershipPolicy policy = |
| base::scoped_policy::ASSUME) { |
| if (object && policy == base::scoped_policy::RETAIN) |
| Traits::Retain(object); |
| if (object_) |
| Traits::Release(object_); |
| object_ = object; |
| } |
| |
| bool operator==(T that) const { |
| return object_ == that; |
| } |
| |
| bool operator!=(T that) const { |
| return object_ != that; |
| } |
| |
| operator T() const { |
| return object_; |
| } |
| |
| T get() const { |
| return object_; |
| } |
| |
| void swap(ScopedTypeRef& that) { |
| T temp = that.object_; |
| that.object_ = object_; |
| object_ = temp; |
| } |
| |
| // ScopedTypeRef<>::release() is like scoped_ptr<>::release. It is NOT |
| // a wrapper for Release(). To force a ScopedTypeRef<> object to call |
| // Release(), use ScopedTypeRef<>::reset(). |
| T release() WARN_UNUSED_RESULT { |
| T temp = object_; |
| object_ = NULL; |
| return temp; |
| } |
| |
| private: |
| T object_; |
| }; |
| |
| } // namespace base |
| |
| #endif // BASE_MAC_SCOPED_TYPEREF_H_ |