ref.hxx

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#ifndef INCLUDED_TOOLS_REF_HXX
#define INCLUDED_TOOLS_REF_HXX
 
#include <sal/config.h>
#include <cassert>
#include <tools/toolsdllapi.h>
#include <utility>
 
namespace tools {
 
template<typename T> class SAL_DLLPUBLIC_RTTI SvRef final {
public:
    SvRef(): pObj(nullptr) {}
 
    SvRef(SvRef&& rObj) noexcept
    {
        pObj = rObj.pObj;
        rObj.pObj = nullptr;
    }
 
    SvRef(SvRef const & rObj): pObj(rObj.pObj)
    {
        if (pObj != nullptr) pObj->AddNextRef();
    }
 
    SvRef(T * pObjP): pObj(pObjP)
    {
        if (pObj != nullptr) pObj->AddFirstRef();
    }
 
    ~SvRef()
    {
        if (pObj != nullptr) pObj->ReleaseRef();
    }
 
    void clear()
    {
        if (pObj != nullptr) {
            T * pRefObj = pObj;
            pObj = nullptr;
            pRefObj->ReleaseRef();
        }
    }
 
    SvRef & operator =(SvRef const & rObj)
    {
        if (rObj.pObj != nullptr) {
            rObj.pObj->AddNextRef();
        }
        T * pRefObj = pObj;
        pObj = rObj.pObj;
        if (pRefObj != nullptr) {
            pRefObj->ReleaseRef();
        }
        return *this;
    }
 
    SvRef & operator =(SvRef && rObj)
    {
        if (pObj != nullptr) {
            pObj->ReleaseRef();
        }
        pObj = rObj.pObj;
        rObj.pObj = nullptr;
        return *this;
    }
 
    bool is()         const { return pObj != nullptr; }
 
    explicit operator bool() const { return is(); }
 
    T * get()         const { return pObj; }
 
    T * operator ->() const { assert(pObj != nullptr); return pObj; }
 
    T & operator *()  const { assert(pObj != nullptr); return *pObj; }
 
    bool operator ==(const SvRef<T> &rhs) const { return pObj == rhs.pObj; }
    bool operator !=(const SvRef<T> &rhs) const { return !(*this == rhs); }
 
private:
    T * pObj;
};
 
template<typename T, typename... Args>
SvRef<T> make_ref(Args&& ... args)
{
    return SvRef<T>(new T(std::forward<Args>(args)...));
}
 
}
 
class TOOLS_DLLPUBLIC SvRefBase
{
    // work around a clang 3.5 optimization bug: if the bNoDelete is *first*
    // it mis-compiles "if (--nRefCount == 0)" and never deletes any object
    unsigned int nRefCount : 31;
    // the only reason this is not bool is because MSVC cannot handle mixed type bitfields
    unsigned int bNoDelete : 1;
 
protected:
    virtual         ~SvRefBase() COVERITY_NOEXCEPT_FALSE;
 
public:
                    SvRefBase() : nRefCount(0), bNoDelete(1) {}
                    SvRefBase(const SvRefBase &) : nRefCount(0), bNoDelete(1) {}
 
    SvRefBase &     operator=(const SvRefBase &) { return *this; }
 
    void            RestoreNoDelete()
                    { bNoDelete = 1; }
 
    void            AddNextRef()
                    {
                        assert( nRefCount < (1 << 30) && "Do not add refs to dead objects" );
                        ++nRefCount;
                    }
 
    void            AddFirstRef()
                    {
                        assert( nRefCount < (1 << 30) && "Do not add refs to dead objects" );
                        if( bNoDelete )
                            bNoDelete = 0;
                        ++nRefCount;
                    }
 
    void            ReleaseRef()
                    {
                        assert( nRefCount >= 1);
                        if( --nRefCount == 0 && !bNoDelete)
                        {
                            // I'm not sure about the original purpose of this line, but right now
                            // it serves the purpose that anything that attempts to do an AddRef()
                            // after an object is deleted will trip an assert.
                            nRefCount = 1 << 30;
                            delete this;
                        }
                    }
 
    unsigned int    GetRefCount() const
                    { return nRefCount; }
};
 
template<typename T>
class SvCompatWeakBase;
 
template<typename T>
class SvCompatWeakHdl final : public SvRefBase
{
    friend class SvCompatWeakBase<T>;
    T* _pObj;
 
    SvCompatWeakHdl( T* pObj ) : _pObj( pObj ) {}
 
public:
    void  ResetWeakBase( ) { _pObj = nullptr; }
    T*    GetObj()        { return _pObj; }
};
 
template<typename T>
class SvCompatWeakBase
{
    tools::SvRef< SvCompatWeakHdl<T> > _xHdl;
 
public:
    SvCompatWeakBase( T* pObj ) { _xHdl = new SvCompatWeakHdl<T>( pObj ); }
 
    ~SvCompatWeakBase() { _xHdl->ResetWeakBase(); }
 
    SvCompatWeakHdl<T>* GetHdl() { return _xHdl.get(); }
};
 
template<typename T>
class SAL_WARN_UNUSED SvCompatWeakRef
{
    tools::SvRef< SvCompatWeakHdl<T> > _xHdl;
public:
    SvCompatWeakRef( ) {}
    SvCompatWeakRef( T* pObj )
                         {  if( pObj ) _xHdl = pObj->GetHdl(); }
#if defined(__COVERITY__)
    ~SvCompatWeakRef() COVERITY_NOEXCEPT_FALSE {}
#endif
    SvCompatWeakRef& operator = ( T * pObj )
                         {  _xHdl = pObj ? pObj->GetHdl() : nullptr; return *this; }
    bool          is() const
                         { return _xHdl.is() && _xHdl->GetObj(); }
    explicit operator bool() const { return is(); }
    T*            operator -> () const
                         { return _xHdl.is() ? _xHdl->GetObj() : nullptr; }
    operator T* () const
                         { return _xHdl.is() ? _xHdl->GetObj() : nullptr; }
};
 
#endif
 
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