1 //== llvm/ADT/IntrusiveRefCntPtr.h - Smart Refcounting Pointer ---*- C++ -*-==// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines IntrusiveRefCntPtr, a template class that 11 // implements a "smart" pointer for objects that maintain their own 12 // internal reference count, and RefCountedBase/RefCountedBaseVPTR, two 13 // generic base classes for objects that wish to have their lifetimes 14 // managed using reference counting. 15 // 16 // IntrusiveRefCntPtr is similar to Boost's intrusive_ptr with added 17 // LLVM-style casting. 18 // 19 //===----------------------------------------------------------------------===// 20 21 #ifndef LLVM_ADT_INTRUSIVE_REF_CNT_PTR 22 #define LLVM_ADT_INTRUSIVE_REF_CNT_PTR 23 24 #include <cassert> 25 26 #include "llvm/Support/Casting.h" 27 28 namespace llvm { 29 30 template <class T> 31 class IntrusiveRefCntPtr; 32 33 //===----------------------------------------------------------------------===// 34 /// RefCountedBase - A generic base class for objects that wish to 35 /// have their lifetimes managed using reference counts. Classes 36 /// subclass RefCountedBase to obtain such functionality, and are 37 /// typically handled with IntrusivePtr "smart pointers" (see below) 38 /// which automatically handle the management of reference counts. 39 /// Objects that subclass RefCountedBase should not be allocated on 40 /// the stack, as invoking "delete" (which is called when the 41 /// reference count hits 0) on such objects is an error. 42 //===----------------------------------------------------------------------===// 43 template <class Derived> 44 class RefCountedBase { 45 mutable unsigned ref_cnt; 46 47 public: 48 RefCountedBase() : ref_cnt(0) {} 49 RefCountedBase(const RefCountedBase &) : ref_cnt(0) {} 50 51 void Retain() const { ++ref_cnt; } 52 void Release() const { 53 assert (ref_cnt > 0 && "Reference count is already zero."); 54 if (--ref_cnt == 0) delete static_cast<const Derived*>(this); 55 } 56 }; 57 58 //===----------------------------------------------------------------------===// 59 /// RefCountedBaseVPTR - A class that has the same function as 60 /// RefCountedBase, but with a virtual destructor. Should be used 61 /// instead of RefCountedBase for classes that already have virtual 62 /// methods to enforce dynamic allocation via 'new'. Classes that 63 /// inherit from RefCountedBaseVPTR can't be allocated on stack - 64 /// attempting to do this will produce a compile error. 65 //===----------------------------------------------------------------------===// 66 class RefCountedBaseVPTR { 67 mutable unsigned ref_cnt; 68 virtual void anchor(); 69 70 protected: 71 RefCountedBaseVPTR() : ref_cnt(0) {} 72 RefCountedBaseVPTR(const RefCountedBaseVPTR &) : ref_cnt(0) {} 73 74 virtual ~RefCountedBaseVPTR() {} 75 76 void Retain() const { ++ref_cnt; } 77 void Release() const { 78 assert (ref_cnt > 0 && "Reference count is already zero."); 79 if (--ref_cnt == 0) delete this; 80 } 81 82 template <typename T> 83 friend struct IntrusiveRefCntPtrInfo; 84 }; 85 86 87 template <typename T> struct IntrusiveRefCntPtrInfo { 88 static void retain(T *obj) { obj->Retain(); } 89 static void release(T *obj) { obj->Release(); } 90 }; 91 92 //===----------------------------------------------------------------------===// 93 /// IntrusiveRefCntPtr - A template class that implements a "smart pointer" 94 /// that assumes the wrapped object has a reference count associated 95 /// with it that can be managed via calls to 96 /// IntrusivePtrAddRef/IntrusivePtrRelease. The smart pointers 97 /// manage reference counts via the RAII idiom: upon creation of 98 /// smart pointer the reference count of the wrapped object is 99 /// incremented and upon destruction of the smart pointer the 100 /// reference count is decremented. This class also safely handles 101 /// wrapping NULL pointers. 102 /// 103 /// Reference counting is implemented via calls to 104 /// Obj->Retain()/Obj->Release(). Release() is required to destroy 105 /// the object when the reference count reaches zero. Inheriting from 106 /// RefCountedBase/RefCountedBaseVPTR takes care of this 107 /// automatically. 108 //===----------------------------------------------------------------------===// 109 template <typename T> 110 class IntrusiveRefCntPtr { 111 T* Obj; 112 typedef IntrusiveRefCntPtr this_type; 113 public: 114 typedef T element_type; 115 116 explicit IntrusiveRefCntPtr() : Obj(0) {} 117 118 IntrusiveRefCntPtr(T* obj) : Obj(obj) { 119 retain(); 120 } 121 122 IntrusiveRefCntPtr(const IntrusiveRefCntPtr& S) : Obj(S.Obj) { 123 retain(); 124 } 125 126 template <class X> 127 IntrusiveRefCntPtr(const IntrusiveRefCntPtr<X>& S) 128 : Obj(S.getPtr()) { 129 retain(); 130 } 131 132 IntrusiveRefCntPtr& operator=(const IntrusiveRefCntPtr& S) { 133 replace(S.getPtr()); 134 return *this; 135 } 136 137 template <class X> 138 IntrusiveRefCntPtr& operator=(const IntrusiveRefCntPtr<X>& S) { 139 replace(S.getPtr()); 140 return *this; 141 } 142 143 IntrusiveRefCntPtr& operator=(T * S) { 144 replace(S); 145 return *this; 146 } 147 148 ~IntrusiveRefCntPtr() { release(); } 149 150 T& operator*() const { return *Obj; } 151 152 T* operator->() const { return Obj; } 153 154 T* getPtr() const { return Obj; } 155 156 typedef T* (IntrusiveRefCntPtr::*unspecified_bool_type) () const; 157 operator unspecified_bool_type() const { 158 return Obj == 0 ? 0 : &IntrusiveRefCntPtr::getPtr; 159 } 160 161 void swap(IntrusiveRefCntPtr& other) { 162 T* tmp = other.Obj; 163 other.Obj = Obj; 164 Obj = tmp; 165 } 166 167 void reset() { 168 release(); 169 Obj = 0; 170 } 171 172 void resetWithoutRelease() { 173 Obj = 0; 174 } 175 176 private: 177 void retain() { if (Obj) IntrusiveRefCntPtrInfo<T>::retain(Obj); } 178 void release() { if (Obj) IntrusiveRefCntPtrInfo<T>::release(Obj); } 179 180 void replace(T* S) { 181 this_type(S).swap(*this); 182 } 183 }; 184 185 template<class T, class U> 186 inline bool operator==(const IntrusiveRefCntPtr<T>& A, 187 const IntrusiveRefCntPtr<U>& B) 188 { 189 return A.getPtr() == B.getPtr(); 190 } 191 192 template<class T, class U> 193 inline bool operator!=(const IntrusiveRefCntPtr<T>& A, 194 const IntrusiveRefCntPtr<U>& B) 195 { 196 return A.getPtr() != B.getPtr(); 197 } 198 199 template<class T, class U> 200 inline bool operator==(const IntrusiveRefCntPtr<T>& A, 201 U* B) 202 { 203 return A.getPtr() == B; 204 } 205 206 template<class T, class U> 207 inline bool operator!=(const IntrusiveRefCntPtr<T>& A, 208 U* B) 209 { 210 return A.getPtr() != B; 211 } 212 213 template<class T, class U> 214 inline bool operator==(T* A, 215 const IntrusiveRefCntPtr<U>& B) 216 { 217 return A == B.getPtr(); 218 } 219 220 template<class T, class U> 221 inline bool operator!=(T* A, 222 const IntrusiveRefCntPtr<U>& B) 223 { 224 return A != B.getPtr(); 225 } 226 227 //===----------------------------------------------------------------------===// 228 // LLVM-style downcasting support for IntrusiveRefCntPtr objects 229 //===----------------------------------------------------------------------===// 230 231 template<class T> struct simplify_type<IntrusiveRefCntPtr<T> > { 232 typedef T* SimpleType; 233 static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) { 234 return Val.getPtr(); 235 } 236 }; 237 238 template<class T> struct simplify_type<const IntrusiveRefCntPtr<T> > { 239 typedef T* SimpleType; 240 static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) { 241 return Val.getPtr(); 242 } 243 }; 244 245 } // end namespace llvm 246 247 #endif // LLVM_ADT_INTRUSIVE_REF_CNT_PTR 248
