Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 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_ |