/* $Id$ */ /* * This file is part of OpenTTD. * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2. * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>. */ /** @file countedptr.hpp CCountedPtr - smart pointer implementation. */ #ifndef COUNTEDPTR_HPP #define COUNTEDPTR_HPP /** * CCountedPtr - simple reference counting smart pointer. * * One of the standard ways how to maintain object's lifetime. * * See http://ootips.org/yonat/4dev/smart-pointers.html for more * general info about smart pointers. * * This class implements ref-counted pointer for objects/interfaces that * support AddRef() and Release() methods. */ template <class Tcls_> class CCountedPtr { /** redefine the template argument to make it visible for derived classes */ public: typedef Tcls_ Tcls; protected: /** here we hold our pointer to the target */ Tcls *m_pT; public: /** default (NULL) construct or construct from a raw pointer */ inline CCountedPtr(Tcls *pObj = NULL) : m_pT(pObj) {AddRef();} /** copy constructor (invoked also when initializing from another smart ptr) */ inline CCountedPtr(const CCountedPtr& src) : m_pT(src.m_pT) {AddRef();} /** destructor releasing the reference */ inline ~CCountedPtr() {Release();} protected: /** add one ref to the underlaying object */ inline void AddRef() {if (m_pT != NULL) m_pT->AddRef();} public: /** release smart pointer (and decrement ref count) if not null */ inline void Release() {if (m_pT != NULL) {Tcls *pT = m_pT; m_pT = NULL; pT->Release();}} /** dereference of smart pointer - const way */ inline const Tcls *operator -> () const {assert(m_pT != NULL); return m_pT;} /** dereference of smart pointer - non const way */ inline Tcls *operator -> () {assert(m_pT != NULL); return m_pT;} /** raw pointer casting operator - const way */ inline operator const Tcls*() const {assert(m_pT == NULL); return m_pT;} /** raw pointer casting operator - non-const way */ inline operator Tcls*() {return m_pT;} /** operator & to support output arguments */ inline Tcls** operator &() {assert(m_pT == NULL); return &m_pT;} /** assignment operator from raw ptr */ inline CCountedPtr& operator = (Tcls *pT) {Assign(pT); return *this;} /** assignment operator from another smart ptr */ inline CCountedPtr& operator = (const CCountedPtr& src) {Assign(src.m_pT); return *this;} /** assignment operator helper */ inline void Assign(Tcls *pT); /** one way how to test for NULL value */ inline bool IsNull() const {return m_pT == NULL;} /** another way how to test for NULL value */ //inline bool operator == (const CCountedPtr& sp) const {return m_pT == sp.m_pT;} /** yet another way how to test for NULL value */ //inline bool operator != (const CCountedPtr& sp) const {return m_pT != sp.m_pT;} /** assign pointer w/o incrementing ref count */ inline void Attach(Tcls *pT) {Release(); m_pT = pT;} /** detach pointer w/o decrementing ref count */ inline Tcls *Detach() {Tcls *pT = m_pT; m_pT = NULL; return pT;} }; template <class Tcls_> inline void CCountedPtr<Tcls_>::Assign(Tcls *pT) { /* if they are the same, we do nothing */ if (pT != m_pT) { if (pT != NULL) pT->AddRef(); // AddRef new pointer if any Tcls *pTold = m_pT; // save original ptr m_pT = pT; // update m_pT to new value if (pTold != NULL) pTold->Release(); // release old ptr if any } } /** * Adapter wrapper for CCountedPtr like classes that can't be used directly by stl * collections as item type. For example CCountedPtr has overloaded operator & which * prevents using CCountedPtr in stl collections (i.e. std::list<CCountedPtr<MyType> >) */ template <class T> struct AdaptT { T m_t; /** construct by wrapping the given object */ AdaptT(const T &t) : m_t(t) {} /** assignment operator */ T& operator = (const T &t) { m_t = t; return t; } /** type-cast operator (used when AdaptT is used instead of T) */ operator T& () { return m_t; } /** const type-cast operator (used when AdaptT is used instead of const T) */ operator const T& () const { return m_t; } }; /** * Simple counted object. Use it as base of your struct/class if you want to use * basic reference counting. Your struct/class will destroy and free itself when * last reference to it is released (using Release() method). The initial reference * count (when it is created) is zero (don't forget AddRef() at least one time if * not using CCountedPtr<T>. * * @see misc/countedobj.cpp for implementation. */ struct SimpleCountedObject { int32 m_ref_cnt; SimpleCountedObject() : m_ref_cnt(0) {} virtual ~SimpleCountedObject() {} virtual int32 AddRef(); virtual int32 Release(); virtual void FinalRelease() {}; }; #endif /* COUNTEDPTR_HPP */