RetainPtr.h   [plain text]

/*
 *  Copyright (C) 2005, 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public License
 *  along with this library; see the file COPYING.LIB.  If not, write to
 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301, USA.
 *
 */

#ifndef RetainPtr_h
#define RetainPtr_h

#include "HashTraits.h"
#include "NullPtr.h"
#include "TypeTraits.h"
#include <algorithm>

#if USE(CF)
#include <CoreFoundation/CoreFoundation.h>
#endif

#ifdef __OBJC__
#import <Foundation/Foundation.h>
#endif

namespace WTF {

    // Unlike most most of our smart pointers, RetainPtr can take either the pointer type or the pointed-to type,
    // so both RetainPtr<NSDictionary> and RetainPtr<CFDictionaryRef> will work.

    enum AdoptCFTag { AdoptCF };
    enum AdoptNSTag { AdoptNS };
    
#ifdef __OBJC__
    inline void adoptNSReference(id ptr)
    {
        if (ptr) {
            CFRetain(ptr);
            [ptr release];
        }
    }
#endif

    template<typename T> class RetainPtr {
    public:
        typedef typename RemovePointer<T>::Type ValueType;
        typedef ValueType* PtrType;

        RetainPtr() : m_ptr(0) {}
        RetainPtr(PtrType ptr) : m_ptr(ptr) { if (ptr) CFRetain(ptr); }

        RetainPtr(AdoptCFTag, PtrType ptr) : m_ptr(ptr) { }
        RetainPtr(AdoptNSTag, PtrType ptr) : m_ptr(ptr) { adoptNSReference(ptr); }
        
        RetainPtr(const RetainPtr& o) : m_ptr(o.m_ptr) { if (PtrType ptr = m_ptr) CFRetain(ptr); }

#if COMPILER_SUPPORTS(CXX_RVALUE_REFERENCES)
        RetainPtr(RetainPtr&& o) : m_ptr(o.leakRef()) { }
#endif

        // Hash table deleted values, which are only constructed and never copied or destroyed.
        RetainPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
        bool isHashTableDeletedValue() const { return m_ptr == hashTableDeletedValue(); }
        
        ~RetainPtr() { if (PtrType ptr = m_ptr) CFRelease(ptr); }
        
        template<typename U> RetainPtr(const RetainPtr<U>&);
        
        PtrType get() const { return m_ptr; }

        void clear();
        PtrType leakRef() WARN_UNUSED_RETURN;
        
        PtrType releaseRef() { return leakRef(); }

        PtrType operator->() const { return m_ptr; }
        
        bool operator!() const { return !m_ptr; }
    
        // This conversion operator allows implicit conversion to bool but not to other integer types.
        typedef PtrType RetainPtr::*UnspecifiedBoolType;
        operator UnspecifiedBoolType() const { return m_ptr ? &RetainPtr::m_ptr : 0; }
        
        RetainPtr& operator=(const RetainPtr&);
        template<typename U> RetainPtr& operator=(const RetainPtr<U>&);
        RetainPtr& operator=(PtrType);
        template<typename U> RetainPtr& operator=(U*);

#if COMPILER_SUPPORTS(CXX_RVALUE_REFERENCES)
        RetainPtr& operator=(RetainPtr&&);
        template<typename U> RetainPtr& operator=(RetainPtr<U>&&);
#endif

#if !HAVE(NULLPTR)
        RetainPtr& operator=(std::nullptr_t) { clear(); return *this; }
#endif

        void adoptCF(PtrType);
        void adoptNS(PtrType);
        
        void swap(RetainPtr&);

    private:
        static PtrType hashTableDeletedValue() { return reinterpret_cast<PtrType>(-1); }

        PtrType m_ptr;
    };
    
    template<typename T> template<typename U> inline RetainPtr<T>::RetainPtr(const RetainPtr<U>& o)
        : m_ptr(o.get())
    {
        if (PtrType ptr = m_ptr)
            CFRetain(ptr);
    }

    template<typename T> inline void RetainPtr<T>::clear()
    {
        if (PtrType ptr = m_ptr) {
            m_ptr = 0;
            CFRelease(ptr);
        }
    }

    template<typename T> inline typename RetainPtr<T>::PtrType RetainPtr<T>::leakRef()
    {
        PtrType ptr = m_ptr;
        m_ptr = 0;
        return ptr;
    }

    template<typename T> inline RetainPtr<T>& RetainPtr<T>::operator=(const RetainPtr<T>& o)
    {
        PtrType optr = o.get();
        if (optr)
            CFRetain(optr);
        PtrType ptr = m_ptr;
        m_ptr = optr;
        if (ptr)
            CFRelease(ptr);
        return *this;
    }
    
    template<typename T> template<typename U> inline RetainPtr<T>& RetainPtr<T>::operator=(const RetainPtr<U>& o)
    {
        PtrType optr = o.get();
        if (optr)
            CFRetain(optr);
        PtrType ptr = m_ptr;
        m_ptr = optr;
        if (ptr)
            CFRelease(ptr);
        return *this;
    }

    template<typename T> inline RetainPtr<T>& RetainPtr<T>::operator=(PtrType optr)
    {
        if (optr)
            CFRetain(optr);
        PtrType ptr = m_ptr;
        m_ptr = optr;
        if (ptr)
            CFRelease(ptr);
        return *this;
    }

    template<typename T> template<typename U> inline RetainPtr<T>& RetainPtr<T>::operator=(U* optr)
    {
        if (optr)
            CFRetain(optr);
        PtrType ptr = m_ptr;
        m_ptr = optr;
        if (ptr)
            CFRelease(ptr);
        return *this;
    }

#if COMPILER_SUPPORTS(CXX_RVALUE_REFERENCES)
    template<typename T> inline RetainPtr<T>& RetainPtr<T>::operator=(RetainPtr<T>&& o)
    {
        adoptCF(o.leakRef());
        return *this;
    }
    
    template<typename T> template<typename U> inline RetainPtr<T>& RetainPtr<T>::operator=(RetainPtr<U>&& o)
    {
        adoptCF(o.leakRef());
        return *this;
    }
#endif

    template<typename T> inline void RetainPtr<T>::adoptCF(PtrType optr)
    {
        PtrType ptr = m_ptr;
        m_ptr = optr;
        if (ptr)
            CFRelease(ptr);
    }

    template<typename T> inline void RetainPtr<T>::adoptNS(PtrType optr)
    {
        adoptNSReference(optr);
        
        PtrType ptr = m_ptr;
        m_ptr = optr;
        if (ptr)
            CFRelease(ptr);
    }

    template<typename T> inline void RetainPtr<T>::swap(RetainPtr<T>& o)
    {
        std::swap(m_ptr, o.m_ptr);
    }

    template<typename T> inline void swap(RetainPtr<T>& a, RetainPtr<T>& b)
    {
        a.swap(b);
    }

    template<typename T, typename U> inline bool operator==(const RetainPtr<T>& a, const RetainPtr<U>& b)
    { 
        return a.get() == b.get(); 
    }

    template<typename T, typename U> inline bool operator==(const RetainPtr<T>& a, U* b)
    { 
        return a.get() == b; 
    }
    
    template<typename T, typename U> inline bool operator==(T* a, const RetainPtr<U>& b) 
    {
        return a == b.get(); 
    }
    
    template<typename T, typename U> inline bool operator!=(const RetainPtr<T>& a, const RetainPtr<U>& b)
    { 
        return a.get() != b.get(); 
    }

    template<typename T, typename U> inline bool operator!=(const RetainPtr<T>& a, U* b)
    {
        return a.get() != b; 
    }

    template<typename T, typename U> inline bool operator!=(T* a, const RetainPtr<U>& b)
    { 
        return a != b.get(); 
    }

    template<typename T> inline RetainPtr<T> adoptCF(T) WARN_UNUSED_RETURN;
    template<typename T> inline RetainPtr<T> adoptCF(T o)
    {
        return RetainPtr<T>(AdoptCF, o);
    }

    template<typename T> inline RetainPtr<T> adoptNS(T) WARN_UNUSED_RETURN;
    template<typename T> inline RetainPtr<T> adoptNS(T o)
    {
        return RetainPtr<T>(AdoptNS, o);
    }

    template<typename P> struct HashTraits<RetainPtr<P> > : SimpleClassHashTraits<RetainPtr<P> > { };
    
    template<typename P> struct PtrHash<RetainPtr<P> > : PtrHash<typename RetainPtr<P>::PtrType> {
        using PtrHash<typename RetainPtr<P>::PtrType>::hash;
        static unsigned hash(const RetainPtr<P>& key) { return hash(key.get()); }
        using PtrHash<typename RetainPtr<P>::PtrType>::equal;
        static bool equal(const RetainPtr<P>& a, const RetainPtr<P>& b) { return a == b; }
        static bool equal(typename RetainPtr<P>::PtrType a, const RetainPtr<P>& b) { return a == b; }
        static bool equal(const RetainPtr<P>& a, typename RetainPtr<P>::PtrType b) { return a == b; }
    };
    
    template<typename P> struct DefaultHash<RetainPtr<P> > { typedef PtrHash<RetainPtr<P> > Hash; };

} // namespace WTF

using WTF::AdoptCF;
using WTF::AdoptNS;
using WTF::adoptCF;
using WTF::adoptNS;
using WTF::RetainPtr;

#endif // WTF_RetainPtr_h