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 {
48 RefCountedBase() : ref_cnt(0) {}
50 void Retain() { ++ref_cnt; }
52 assert (ref_cnt > 0 && "Reference count is already zero.");
53 if (--ref_cnt == 0) delete static_cast<Derived*>(this);
56 friend class IntrusiveRefCntPtr<Derived>;
59 //===----------------------------------------------------------------------===//
60 /// RefCountedBaseVPTR - A class that has the same function as
61 /// RefCountedBase, but with a virtual destructor. Should be used
62 /// instead of RefCountedBase for classes that already have virtual
63 /// methods to enforce dynamic allocation via 'new'. Classes that
64 /// inherit from RefCountedBaseVPTR can't be allocated on stack -
65 /// attempting to do this will produce a compile error.
66 //===----------------------------------------------------------------------===//
67 template <class Derived>
68 class RefCountedBaseVPTR {
72 RefCountedBaseVPTR() : ref_cnt(0) {}
73 virtual ~RefCountedBaseVPTR() {}
75 void Retain() { ++ref_cnt; }
77 assert (ref_cnt > 0 && "Reference count is already zero.");
78 if (--ref_cnt == 0) delete this;
81 friend class IntrusiveRefCntPtr<Derived>;
84 //===----------------------------------------------------------------------===//
85 /// IntrusiveRefCntPtr - A template class that implements a "smart pointer"
86 /// that assumes the wrapped object has a reference count associated
87 /// with it that can be managed via calls to
88 /// IntrusivePtrAddRef/IntrusivePtrRelease. The smart pointers
89 /// manage reference counts via the RAII idiom: upon creation of
90 /// smart pointer the reference count of the wrapped object is
91 /// incremented and upon destruction of the smart pointer the
92 /// reference count is decremented. This class also safely handles
93 /// wrapping NULL pointers.
95 /// Reference counting is implemented via calls to
96 /// Obj->Retain()/Obj->Release(). Release() is required to destroy
97 /// the object when the reference count reaches zero. Inheriting from
98 /// RefCountedBase/RefCountedBaseVPTR takes care of this
100 //===----------------------------------------------------------------------===//
101 template <typename T>
102 class IntrusiveRefCntPtr {
104 typedef IntrusiveRefCntPtr this_type;
106 typedef T element_type;
108 explicit IntrusiveRefCntPtr() : Obj(0) {}
110 explicit IntrusiveRefCntPtr(T* obj) : Obj(obj) {
114 IntrusiveRefCntPtr(const IntrusiveRefCntPtr& S) : Obj(S.Obj) {
119 IntrusiveRefCntPtr(const IntrusiveRefCntPtr<X>& S)
124 IntrusiveRefCntPtr& operator=(const IntrusiveRefCntPtr& S) {
130 IntrusiveRefCntPtr& operator=(const IntrusiveRefCntPtr<X>& S) {
135 IntrusiveRefCntPtr& operator=(T * S) {
140 ~IntrusiveRefCntPtr() { release(); }
142 T& operator*() const { return *Obj; }
144 T* operator->() const { return Obj; }
146 T* getPtr() const { return Obj; }
148 typedef T* (IntrusiveRefCntPtr::*unspecified_bool_type) () const;
149 operator unspecified_bool_type() const {
150 return Obj == 0 ? 0 : &IntrusiveRefCntPtr::getPtr;
153 void swap(IntrusiveRefCntPtr& other) {
160 void retain() { if (Obj) Obj->Retain(); }
161 void release() { if (Obj) Obj->Release(); }
164 this_type(S).swap(*this);
168 template<class T, class U>
169 inline bool operator==(const IntrusiveRefCntPtr<T>& A,
170 const IntrusiveRefCntPtr<U>& B)
172 return A.getPtr() == B.getPtr();
175 template<class T, class U>
176 inline bool operator!=(const IntrusiveRefCntPtr<T>& A,
177 const IntrusiveRefCntPtr<U>& B)
179 return A.getPtr() != B.getPtr();
182 template<class T, class U>
183 inline bool operator==(const IntrusiveRefCntPtr<T>& A,
186 return A.getPtr() == B;
189 template<class T, class U>
190 inline bool operator!=(const IntrusiveRefCntPtr<T>& A,
193 return A.getPtr() != B;
196 template<class T, class U>
197 inline bool operator==(T* A,
198 const IntrusiveRefCntPtr<U>& B)
200 return A == B.getPtr();
203 template<class T, class U>
204 inline bool operator!=(T* A,
205 const IntrusiveRefCntPtr<U>& B)
207 return A != B.getPtr();
210 //===----------------------------------------------------------------------===//
211 // LLVM-style downcasting support for IntrusiveRefCntPtr objects
212 //===----------------------------------------------------------------------===//
214 template<class T> struct simplify_type<IntrusiveRefCntPtr<T> > {
215 typedef T* SimpleType;
216 static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) {
221 template<class T> struct simplify_type<const IntrusiveRefCntPtr<T> > {
222 typedef T* SimpleType;
223 static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) {
228 } // end namespace llvm
230 #endif // LLVM_ADT_INTRUSIVE_REF_CNT_PTR