| // Copyright 2020 The Dawn & Tint Authors |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are met: |
| // |
| // 1. Redistributions of source code must retain the above copyright notice, this |
| // list of conditions and the following disclaimer. |
| // |
| // 2. Redistributions in binary form must reproduce the above copyright notice, |
| // this list of conditions and the following disclaimer in the documentation |
| // and/or other materials provided with the distribution. |
| // |
| // 3. Neither the name of the copyright holder nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE |
| // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
| // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef SRC_DAWN_COMMON_REFBASE_H_ |
| #define SRC_DAWN_COMMON_REFBASE_H_ |
| |
| #include <type_traits> |
| #include <utility> |
| |
| #include "dawn/common/Assert.h" |
| #include "dawn/common/Compiler.h" |
| |
| namespace dawn { |
| |
| // A common class for various smart-pointers acting on referenceable/releasable pointer-like |
| // objects. Logic for each specialization can be customized using a Traits type that looks |
| // like the following: |
| // |
| // struct { |
| // static constexpr T kNullValue = ...; |
| // static void AddRef(T value) { ... } |
| // static void Release(T value) { ... } |
| // }; |
| // |
| // RefBase supports |
| template <typename T, typename Traits> |
| class RefBase { |
| public: |
| // Default constructor and destructor. |
| RefBase() : mValue(Traits::kNullValue) {} |
| |
| ~RefBase() { Release(mValue); } |
| |
| // Constructors from nullptr. |
| // NOLINTNEXTLINE(runtime/explicit) |
| constexpr RefBase(std::nullptr_t) : RefBase() {} |
| |
| RefBase<T, Traits>& operator=(std::nullptr_t) { |
| Set(Traits::kNullValue); |
| return *this; |
| } |
| |
| // Constructors from a value T. |
| // NOLINTNEXTLINE(runtime/explicit) |
| RefBase(T value) : mValue(value) { AddRef(value); } |
| |
| RefBase<T, Traits>& operator=(const T& value) { |
| Set(value); |
| return *this; |
| } |
| |
| // Constructors from a RefBase<T> |
| RefBase(const RefBase<T, Traits>& other) : mValue(other.mValue) { AddRef(other.mValue); } |
| |
| RefBase<T, Traits>& operator=(const RefBase<T, Traits>& other) { |
| Set(other.mValue); |
| return *this; |
| } |
| |
| RefBase(RefBase<T, Traits>&& other) { mValue = other.Detach(); } |
| |
| RefBase<T, Traits>& operator=(RefBase<T, Traits>&& other) { |
| if (&other != this) { |
| Release(mValue); |
| mValue = other.Detach(); |
| } |
| return *this; |
| } |
| |
| // Constructors from a RefBase<U>. Note that in the *-assignment operators this cannot be the |
| // same as `other` because overload resolution rules would have chosen the *-assignement |
| // operators defined with `other` == RefBase<T, Traits>. |
| template <typename U, typename UTraits, typename = typename std::is_convertible<U, T>::type> |
| RefBase(const RefBase<U, UTraits>& other) : mValue(other.mValue) { |
| AddRef(other.mValue); |
| } |
| |
| template <typename U, typename UTraits, typename = typename std::is_convertible<U, T>::type> |
| RefBase<T, Traits>& operator=(const RefBase<U, UTraits>& other) { |
| Set(other.mValue); |
| return *this; |
| } |
| |
| template <typename U, typename UTraits, typename = typename std::is_convertible<U, T>::type> |
| RefBase(RefBase<U, UTraits>&& other) { |
| mValue = other.Detach(); |
| } |
| |
| template <typename U, typename UTraits, typename = typename std::is_convertible<U, T>::type> |
| RefBase<T, Traits>& operator=(RefBase<U, UTraits>&& other) { |
| Release(mValue); |
| mValue = other.Detach(); |
| return *this; |
| } |
| |
| explicit operator bool() const { return !!mValue; } |
| |
| // Comparison operators. |
| bool operator==(const T& other) const { return mValue == other; } |
| bool operator!=(const T& other) const { return mValue != other; } |
| |
| bool operator==(const RefBase<T, Traits>& other) const { return mValue == other.mValue; } |
| bool operator!=(const RefBase<T, Traits>& other) const { return mValue != other.mValue; } |
| |
| const T operator->() const { return mValue; } |
| T operator->() { return mValue; } |
| |
| bool operator<(const RefBase<T, Traits>& other) const { return mValue < other.mValue; } |
| |
| // Smart pointer methods. |
| const T& Get() const { return mValue; } |
| T& Get() { return mValue; } |
| |
| [[nodiscard]] T Detach() { |
| T value{std::move(mValue)}; |
| mValue = Traits::kNullValue; |
| return value; |
| } |
| |
| void Acquire(T value) { |
| Release(mValue); |
| mValue = value; |
| } |
| |
| [[nodiscard]] T* InitializeInto() { |
| DAWN_ASSERT(mValue == Traits::kNullValue); |
| return &mValue; |
| } |
| |
| // Cast operator. |
| template <typename Other> |
| Other Cast() && { |
| Other other; |
| CastImpl(this, &other); |
| return other; |
| } |
| |
| private: |
| // Friend is needed so that instances of RefBase<U> can call AddRef and Release on |
| // RefBase<T>. |
| template <typename U, typename UTraits> |
| friend class RefBase; |
| |
| template <typename U, typename UTraits, typename = typename std::is_convertible<U, T>::type> |
| static void CastImpl(RefBase<T, Traits>* ref, RefBase<U, UTraits>* other) { |
| other->Acquire(static_cast<U>(ref->Detach())); |
| } |
| |
| static void AddRef(T value) { |
| if (value != Traits::kNullValue) { |
| Traits::AddRef(value); |
| } |
| } |
| static void Release(T value) { |
| if (value != Traits::kNullValue) { |
| Traits::Release(value); |
| } |
| } |
| |
| void Set(T value) { |
| if (mValue != value) { |
| // Ensure that the new value is referenced before the old is released to prevent any |
| // transitive frees that may affect the new value. |
| AddRef(value); |
| Release(mValue); |
| mValue = value; |
| } |
| } |
| |
| T mValue; |
| }; |
| |
| } // namespace dawn |
| |
| #endif // SRC_DAWN_COMMON_REFBASE_H_ |