1 //== llvm/ADT/IntrusiveRefCntPtr.h - Smart Refcounting Pointer ---*- C++ -*-==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
16 // IntrusiveRefCntPtr is similar to Boost's intrusive_ptr with added
17 // LLVM-style casting.
19 //===----------------------------------------------------------------------===//
21 #ifndef LLVM_ADT_INTRUSIVE_REF_CNT_PTR
22 #define LLVM_ADT_INTRUSIVE_REF_CNT_PTR
26 #include "llvm/Support/Casting.h"
31 class IntrusiveRefCntPtr;
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;
48 RefCountedBase() : ref_cnt(0) {}
49 RefCountedBase(const RefCountedBase &) : ref_cnt(0) {}
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);
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;
70 RefCountedBaseVPTR() : ref_cnt(0) {}
71 RefCountedBaseVPTR(const RefCountedBaseVPTR &) : ref_cnt(0) {}
73 virtual ~RefCountedBaseVPTR() {}
75 void Retain() const { ++ref_cnt; }
76 void Release() const {
77 assert (ref_cnt > 0 && "Reference count is already zero.");
78 if (--ref_cnt == 0) delete this;
82 friend class IntrusiveRefCntPtr;
85 //===----------------------------------------------------------------------===//
86 /// IntrusiveRefCntPtr - A template class that implements a "smart pointer"
87 /// that assumes the wrapped object has a reference count associated
88 /// with it that can be managed via calls to
89 /// IntrusivePtrAddRef/IntrusivePtrRelease. The smart pointers
90 /// manage reference counts via the RAII idiom: upon creation of
91 /// smart pointer the reference count of the wrapped object is
92 /// incremented and upon destruction of the smart pointer the
93 /// reference count is decremented. This class also safely handles
94 /// wrapping NULL pointers.
96 /// Reference counting is implemented via calls to
97 /// Obj->Retain()/Obj->Release(). Release() is required to destroy
98 /// the object when the reference count reaches zero. Inheriting from
99 /// RefCountedBase/RefCountedBaseVPTR takes care of this
101 //===----------------------------------------------------------------------===//
102 template <typename T>
103 class IntrusiveRefCntPtr {
105 typedef IntrusiveRefCntPtr this_type;
107 typedef T element_type;
109 explicit IntrusiveRefCntPtr() : Obj(0) {}
111 explicit IntrusiveRefCntPtr(T* obj) : Obj(obj) {
115 IntrusiveRefCntPtr(const IntrusiveRefCntPtr& S) : Obj(S.Obj) {
120 IntrusiveRefCntPtr(const IntrusiveRefCntPtr<X>& S)
125 IntrusiveRefCntPtr& operator=(const IntrusiveRefCntPtr& S) {
131 IntrusiveRefCntPtr& operator=(const IntrusiveRefCntPtr<X>& S) {
136 IntrusiveRefCntPtr& operator=(T * S) {
141 ~IntrusiveRefCntPtr() { release(); }
143 T& operator*() const { return *Obj; }
145 T* operator->() const { return Obj; }
147 T* getPtr() const { return Obj; }
149 typedef T* (IntrusiveRefCntPtr::*unspecified_bool_type) () const;
150 operator unspecified_bool_type() const {
151 return Obj == 0 ? 0 : &IntrusiveRefCntPtr::getPtr;
154 void swap(IntrusiveRefCntPtr& other) {
160 void resetWithoutRelease() {
165 void retain() { if (Obj) Obj->Retain(); }
166 void release() { if (Obj) Obj->Release(); }
169 this_type(S).swap(*this);
173 template<class T, class U>
174 inline bool operator==(const IntrusiveRefCntPtr<T>& A,
175 const IntrusiveRefCntPtr<U>& B)
177 return A.getPtr() == B.getPtr();
180 template<class T, class U>
181 inline bool operator!=(const IntrusiveRefCntPtr<T>& A,
182 const IntrusiveRefCntPtr<U>& B)
184 return A.getPtr() != B.getPtr();
187 template<class T, class U>
188 inline bool operator==(const IntrusiveRefCntPtr<T>& A,
191 return A.getPtr() == B;
194 template<class T, class U>
195 inline bool operator!=(const IntrusiveRefCntPtr<T>& A,
198 return A.getPtr() != B;
201 template<class T, class U>
202 inline bool operator==(T* A,
203 const IntrusiveRefCntPtr<U>& B)
205 return A == B.getPtr();
208 template<class T, class U>
209 inline bool operator!=(T* A,
210 const IntrusiveRefCntPtr<U>& B)
212 return A != B.getPtr();
215 //===----------------------------------------------------------------------===//
216 // LLVM-style downcasting support for IntrusiveRefCntPtr objects
217 //===----------------------------------------------------------------------===//
219 template<class T> struct simplify_type<IntrusiveRefCntPtr<T> > {
220 typedef T* SimpleType;
221 static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) {
226 template<class T> struct simplify_type<const IntrusiveRefCntPtr<T> > {
227 typedef T* SimpleType;
228 static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) {
233 } // end namespace llvm
235 #endif // LLVM_ADT_INTRUSIVE_REF_CNT_PTR