// Copyright 2011 the V8 project 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 V8_SMART_POINTERS_H_ #define V8_SMART_POINTERS_H_ namespace v8 { namespace internal { template<typename Deallocator, typename T> class SmartPointerBase { public: // Default constructor. Constructs an empty scoped pointer. SmartPointerBase() : p_(NULL) {} // Constructs a scoped pointer from a plain one. explicit SmartPointerBase(T* ptr) : p_(ptr) {} // Copy constructor removes the pointer from the original to avoid double // freeing. SmartPointerBase(const SmartPointerBase<Deallocator, T>& rhs) : p_(rhs.p_) { const_cast<SmartPointerBase<Deallocator, T>&>(rhs).p_ = NULL; } T* operator->() const { return p_; } T& operator*() const { return *p_; } T* get() const { return p_; } // You can use [n] to index as if it was a plain pointer. T& operator[](size_t i) { return p_[i]; } // You can use [n] to index as if it was a plain pointer. const T& operator[](size_t i) const { return p_[i]; } // We don't have implicit conversion to a T* since that hinders migration: // You would not be able to change a method from returning a T* to // returning an SmartArrayPointer<T> and then get errors wherever it is used. // If you want to take out the plain pointer and don't want it automatically // deleted then call Detach(). Afterwards, the smart pointer is empty // (NULL). T* Detach() { T* temp = p_; p_ = NULL; return temp; } void Reset(T* new_value) { DCHECK(p_ == NULL || p_ != new_value); if (p_) Deallocator::Delete(p_); p_ = new_value; } // Assignment requires an empty (NULL) SmartArrayPointer as the receiver. Like // the copy constructor it removes the pointer in the original to avoid // double freeing. SmartPointerBase<Deallocator, T>& operator=( const SmartPointerBase<Deallocator, T>& rhs) { DCHECK(is_empty()); T* tmp = rhs.p_; // swap to handle self-assignment const_cast<SmartPointerBase<Deallocator, T>&>(rhs).p_ = NULL; p_ = tmp; return *this; } bool is_empty() const { return p_ == NULL; } protected: // When the destructor of the scoped pointer is executed the plain pointer // is deleted using DeleteArray. This implies that you must allocate with // NewArray. ~SmartPointerBase() { if (p_) Deallocator::Delete(p_); } private: T* p_; }; // A 'scoped array pointer' that calls DeleteArray on its pointer when the // destructor is called. template<typename T> struct ArrayDeallocator { static void Delete(T* array) { DeleteArray(array); } }; template<typename T> class SmartArrayPointer: public SmartPointerBase<ArrayDeallocator<T>, T> { public: SmartArrayPointer() { } explicit SmartArrayPointer(T* ptr) : SmartPointerBase<ArrayDeallocator<T>, T>(ptr) { } SmartArrayPointer(const SmartArrayPointer<T>& rhs) : SmartPointerBase<ArrayDeallocator<T>, T>(rhs) { } }; template<typename T> struct ObjectDeallocator { static void Delete(T* object) { delete object; } }; template<typename T> class SmartPointer: public SmartPointerBase<ObjectDeallocator<T>, T> { public: SmartPointer() { } explicit SmartPointer(T* ptr) : SmartPointerBase<ObjectDeallocator<T>, T>(ptr) { } SmartPointer(const SmartPointer<T>& rhs) : SmartPointerBase<ObjectDeallocator<T>, T>(rhs) { } }; } } // namespace v8::internal #endif // V8_SMART_POINTERS_H_