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) {}
50 void Retain() const { ++ref_cnt; }
51 void Release() const {
52 assert (ref_cnt > 0 && "Reference count is already zero.");
53 if (--ref_cnt == 0) delete static_cast<const Derived*>(this);
57 //===----------------------------------------------------------------------===//
58 /// RefCountedBaseVPTR - A class that has the same function as
59 /// RefCountedBase, but with a virtual destructor. Should be used
60 /// instead of RefCountedBase for classes that already have virtual
61 /// methods to enforce dynamic allocation via 'new'. Classes that
62 /// inherit from RefCountedBaseVPTR can't be allocated on stack -
63 /// attempting to do this will produce a compile error.
64 //===----------------------------------------------------------------------===//
65 class RefCountedBaseVPTR {
66 mutable unsigned ref_cnt;
69 RefCountedBaseVPTR() : ref_cnt(0) {}
70 virtual ~RefCountedBaseVPTR() {}
72 void Retain() const { ++ref_cnt; }
73 void Release() const {
74 assert (ref_cnt > 0 && "Reference count is already zero.");
75 if (--ref_cnt == 0) delete this;
79 friend class IntrusiveRefCntPtr;
82 //===----------------------------------------------------------------------===//
83 /// IntrusiveRefCntPtr - A template class that implements a "smart pointer"
84 /// that assumes the wrapped object has a reference count associated
85 /// with it that can be managed via calls to
86 /// IntrusivePtrAddRef/IntrusivePtrRelease. The smart pointers
87 /// manage reference counts via the RAII idiom: upon creation of
88 /// smart pointer the reference count of the wrapped object is
89 /// incremented and upon destruction of the smart pointer the
90 /// reference count is decremented. This class also safely handles
91 /// wrapping NULL pointers.
93 /// Reference counting is implemented via calls to
94 /// Obj->Retain()/Obj->Release(). Release() is required to destroy
95 /// the object when the reference count reaches zero. Inheriting from
96 /// RefCountedBase/RefCountedBaseVPTR takes care of this
98 //===----------------------------------------------------------------------===//
100 class IntrusiveRefCntPtr {
102 typedef IntrusiveRefCntPtr this_type;
104 typedef T element_type;
106 explicit IntrusiveRefCntPtr() : Obj(0) {}
108 explicit IntrusiveRefCntPtr(T* obj) : Obj(obj) {
112 IntrusiveRefCntPtr(const IntrusiveRefCntPtr& S) : Obj(S.Obj) {
117 IntrusiveRefCntPtr(const IntrusiveRefCntPtr<X>& S)
122 IntrusiveRefCntPtr& operator=(const IntrusiveRefCntPtr& S) {
128 IntrusiveRefCntPtr& operator=(const IntrusiveRefCntPtr<X>& S) {
133 IntrusiveRefCntPtr& operator=(T * S) {
138 ~IntrusiveRefCntPtr() { release(); }
140 T& operator*() const { return *Obj; }
142 T* operator->() const { return Obj; }
144 T* getPtr() const { return Obj; }
146 typedef T* (IntrusiveRefCntPtr::*unspecified_bool_type) () const;
147 operator unspecified_bool_type() const {
148 return Obj == 0 ? 0 : &IntrusiveRefCntPtr::getPtr;
151 void swap(IntrusiveRefCntPtr& other) {
157 void resetWithoutRelease() {
162 void retain() { if (Obj) Obj->Retain(); }
163 void release() { if (Obj) Obj->Release(); }
166 this_type(S).swap(*this);
170 template<class T, class U>
171 inline bool operator==(const IntrusiveRefCntPtr<T>& A,
172 const IntrusiveRefCntPtr<U>& B)
174 return A.getPtr() == B.getPtr();
177 template<class T, class U>
178 inline bool operator!=(const IntrusiveRefCntPtr<T>& A,
179 const IntrusiveRefCntPtr<U>& B)
181 return A.getPtr() != B.getPtr();
184 template<class T, class U>
185 inline bool operator==(const IntrusiveRefCntPtr<T>& A,
188 return A.getPtr() == B;
191 template<class T, class U>
192 inline bool operator!=(const IntrusiveRefCntPtr<T>& A,
195 return A.getPtr() != B;
198 template<class T, class U>
199 inline bool operator==(T* A,
200 const IntrusiveRefCntPtr<U>& B)
202 return A == B.getPtr();
205 template<class T, class U>
206 inline bool operator!=(T* A,
207 const IntrusiveRefCntPtr<U>& B)
209 return A != B.getPtr();
212 //===----------------------------------------------------------------------===//
213 // LLVM-style downcasting support for IntrusiveRefCntPtr objects
214 //===----------------------------------------------------------------------===//
216 template<class T> struct simplify_type<IntrusiveRefCntPtr<T> > {
217 typedef T* SimpleType;
218 static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) {
223 template<class T> struct simplify_type<const IntrusiveRefCntPtr<T> > {
224 typedef T* SimpleType;
225 static SimpleType getSimplifiedValue(const IntrusiveRefCntPtr<T>& Val) {
230 } // end namespace llvm
232 #endif // LLVM_ADT_INTRUSIVE_REF_CNT_PTR