1 // Copyright 2011 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_SMART_POINTERS_H_ 6 #define V8_SMART_POINTERS_H_ 7 8 namespace v8 { 9 namespace internal { 10 11 12 template<typename Deallocator, typename T> 13 class SmartPointerBase { 14 public: 15 // Default constructor. Constructs an empty scoped pointer. 16 SmartPointerBase() : p_(NULL) {} 17 18 // Constructs a scoped pointer from a plain one. 19 explicit SmartPointerBase(T* ptr) : p_(ptr) {} 20 21 // Copy constructor removes the pointer from the original to avoid double 22 // freeing. 23 SmartPointerBase(const SmartPointerBase<Deallocator, T>& rhs) 24 : p_(rhs.p_) { 25 const_cast<SmartPointerBase<Deallocator, T>&>(rhs).p_ = NULL; 26 } 27 28 T* operator->() const { return p_; } 29 30 T& operator*() const { return *p_; } 31 32 T* get() const { return p_; } 33 34 // You can use [n] to index as if it was a plain pointer. 35 T& operator[](size_t i) { 36 return p_[i]; 37 } 38 39 // You can use [n] to index as if it was a plain pointer. 40 const T& operator[](size_t i) const { 41 return p_[i]; 42 } 43 44 // We don't have implicit conversion to a T* since that hinders migration: 45 // You would not be able to change a method from returning a T* to 46 // returning an SmartArrayPointer<T> and then get errors wherever it is used. 47 48 49 // If you want to take out the plain pointer and don't want it automatically 50 // deleted then call Detach(). Afterwards, the smart pointer is empty 51 // (NULL). 52 T* Detach() { 53 T* temp = p_; 54 p_ = NULL; 55 return temp; 56 } 57 58 void Reset(T* new_value) { 59 DCHECK(p_ == NULL || p_ != new_value); 60 if (p_) Deallocator::Delete(p_); 61 p_ = new_value; 62 } 63 64 // Assignment requires an empty (NULL) SmartArrayPointer as the receiver. Like 65 // the copy constructor it removes the pointer in the original to avoid 66 // double freeing. 67 SmartPointerBase<Deallocator, T>& operator=( 68 const SmartPointerBase<Deallocator, T>& rhs) { 69 DCHECK(is_empty()); 70 T* tmp = rhs.p_; // swap to handle self-assignment 71 const_cast<SmartPointerBase<Deallocator, T>&>(rhs).p_ = NULL; 72 p_ = tmp; 73 return *this; 74 } 75 76 bool is_empty() const { return p_ == NULL; } 77 78 protected: 79 // When the destructor of the scoped pointer is executed the plain pointer 80 // is deleted using DeleteArray. This implies that you must allocate with 81 // NewArray. 82 ~SmartPointerBase() { if (p_) Deallocator::Delete(p_); } 83 84 private: 85 T* p_; 86 }; 87 88 // A 'scoped array pointer' that calls DeleteArray on its pointer when the 89 // destructor is called. 90 91 template<typename T> 92 struct ArrayDeallocator { 93 static void Delete(T* array) { 94 DeleteArray(array); 95 } 96 }; 97 98 99 template<typename T> 100 class SmartArrayPointer: public SmartPointerBase<ArrayDeallocator<T>, T> { 101 public: 102 SmartArrayPointer() { } 103 explicit SmartArrayPointer(T* ptr) 104 : SmartPointerBase<ArrayDeallocator<T>, T>(ptr) { } 105 SmartArrayPointer(const SmartArrayPointer<T>& rhs) 106 : SmartPointerBase<ArrayDeallocator<T>, T>(rhs) { } 107 }; 108 109 110 template<typename T> 111 struct ObjectDeallocator { 112 static void Delete(T* object) { 113 delete object; 114 } 115 }; 116 117 118 template<typename T> 119 class SmartPointer: public SmartPointerBase<ObjectDeallocator<T>, T> { 120 public: 121 SmartPointer() { } 122 explicit SmartPointer(T* ptr) 123 : SmartPointerBase<ObjectDeallocator<T>, T>(ptr) { } 124 SmartPointer(const SmartPointer<T>& rhs) 125 : SmartPointerBase<ObjectDeallocator<T>, T>(rhs) { } 126 }; 127 128 } } // namespace v8::internal 129 130 #endif // V8_SMART_POINTERS_H_ 131
