RetainPtr.h   [plain text]

/*
 *  Copyright (C) 2005, 2006, 2007, 2008, 2010, 2013, 2014 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

#if USE(CF) || defined(__OBJC__)

#include <wtf/HashTraits.h>
#include <algorithm>
#include <cstddef>

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

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

#ifndef CF_RELEASES_ARGUMENT
#define CF_RELEASES_ARGUMENT
#endif

#ifndef NS_RELEASES_ARGUMENT
#define NS_RELEASES_ARGUMENT
#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.

    template<typename T> class RetainPtr;

    template<typename T> RetainPtr<T> adoptCF(T CF_RELEASES_ARGUMENT) WARN_UNUSED_RETURN;
    template<typename T> RetainPtr<T> adoptNS(T NS_RELEASES_ARGUMENT) WARN_UNUSED_RETURN;

    template<typename T> class RetainPtr {
    public:
        typedef typename std::remove_pointer<T>::type ValueType;
        typedef ValueType* PtrType;
        typedef CFTypeRef StorageType;

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

        RetainPtr(const RetainPtr& o) : m_ptr(o.m_ptr) { if (StorageType ptr = m_ptr) CFRetain(ptr); }

        RetainPtr(RetainPtr&& o) : m_ptr(toStorageType(o.leakRef())) { }
        template<typename U> RetainPtr(RetainPtr<U>&& o) : m_ptr(toStorageType(o.leakRef())) { }

        // 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 (StorageType ptr = m_ptr) CFRelease(ptr); }
        
        template<typename U> RetainPtr(const RetainPtr<U>&);

        void clear();
        PtrType leakRef() WARN_UNUSED_RETURN;
        PtrType autorelease();

        PtrType get() const { return fromStorageType(m_ptr); }
        PtrType operator->() const { return fromStorageType(m_ptr); }
        explicit operator PtrType() const { return fromStorageType(m_ptr); }
        explicit operator bool() 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 StorageType RetainPtr::*UnspecifiedBoolType;
        operator UnspecifiedBoolType() const { return m_ptr ? &RetainPtr::m_ptr : nullptr; }
        
        RetainPtr& operator=(const RetainPtr&);
        template<typename U> RetainPtr& operator=(const RetainPtr<U>&);
        RetainPtr& operator=(PtrType);
        template<typename U> RetainPtr& operator=(U*);

        RetainPtr& operator=(RetainPtr&&);
        template<typename U> RetainPtr& operator=(RetainPtr<U>&&);

        void swap(RetainPtr&);

        template<typename U> friend RetainPtr<U> adoptCF(U CF_RELEASES_ARGUMENT) WARN_UNUSED_RETURN;
        template<typename U> friend RetainPtr<U> adoptNS(U NS_RELEASES_ARGUMENT) WARN_UNUSED_RETURN;

    private:
        enum AdoptTag { Adopt };
        RetainPtr(PtrType ptr, AdoptTag) : m_ptr(toStorageType(ptr)) { }

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

#if defined (__OBJC__) && __has_feature(objc_arc)
        template<typename U>
        typename std::enable_if<std::is_convertible<U, id>::value, PtrType>::type
        fromStorageTypeHelper(StorageType ptr) const
        {
            return (__bridge PtrType)ptr;
        }

        template<typename U>
        typename std::enable_if<!std::is_convertible<U, id>::value, PtrType>::type
        fromStorageTypeHelper(StorageType ptr) const
        {
            return (PtrType)ptr;
        }

        PtrType fromStorageType(StorageType ptr) const { return fromStorageTypeHelper<PtrType>(ptr); }
        StorageType toStorageType(id ptr) const { return (__bridge StorageType)ptr; }
        StorageType toStorageType(CFTypeRef ptr) const { return (StorageType)ptr; }
#else
        PtrType fromStorageType(StorageType ptr) const { return (PtrType)ptr; }
        StorageType toStorageType(PtrType ptr) const { return (StorageType)ptr; }
#endif

        StorageType m_ptr;
    };

    // Helper function for creating a RetainPtr using template argument deduction.
    template<typename T> inline RetainPtr<T> retainPtr(T) WARN_UNUSED_RETURN;

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

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

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

#ifdef __OBJC__
    template<typename T> inline auto RetainPtr<T>::autorelease() -> PtrType
    {
        return (__bridge PtrType)CFBridgingRelease(leakRef());
    }
#endif

    template<typename T> inline RetainPtr<T>& RetainPtr<T>::operator=(const RetainPtr& o)
    {
        RetainPtr ptr = o;
        swap(ptr);
        return *this;
    }

    template<typename T> template<typename U> inline RetainPtr<T>& RetainPtr<T>::operator=(const RetainPtr<U>& o)
    {
        RetainPtr ptr = o;
        swap(ptr);
        return *this;
    }

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

    template<typename T> template<typename U> inline RetainPtr<T>& RetainPtr<T>::operator=(U* optr)
    {
        RetainPtr ptr = optr;
        swap(ptr);
        return *this;
    }

    template<typename T> inline RetainPtr<T>& RetainPtr<T>::operator=(RetainPtr&& o)
    {
        RetainPtr ptr = WTF::move(o);
        swap(ptr);
        return *this;
    }

    template<typename T> template<typename U> inline RetainPtr<T>& RetainPtr<T>::operator=(RetainPtr<U>&& o)
    {
        RetainPtr ptr = WTF::move(o);
        swap(ptr);
        return *this;
    }

    template<typename T> inline void RetainPtr<T>::swap(RetainPtr& 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 CF_RELEASES_ARGUMENT ptr)
    {
#ifdef __OBJC__
        static_assert((!std::is_convertible<T, id>::value), "Don't use adoptCF with Objective-C pointer types, use adoptNS.");
#endif
        return RetainPtr<T>(ptr, RetainPtr<T>::Adopt);
    }

#ifdef __OBJC__
    template<typename T> inline RetainPtr<T> adoptNS(T NS_RELEASES_ARGUMENT ptr)
    {
#if __has_feature(objc_arc)
        return ptr;
#elif defined(OBJC_NO_GC)
        return RetainPtr<T>(ptr, RetainPtr<T>::Adopt);
#else
        RetainPtr<T> result = ptr;
        [ptr release];
        return result;
#endif
    }
#endif

    template<typename T> inline RetainPtr<T> retainPtr(T ptr)
    {
        return ptr;
    }

    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; };

    template <typename P>
    struct RetainPtrObjectHashTraits : SimpleClassHashTraits<RetainPtr<P>> {
        static const RetainPtr<P>& emptyValue()
        {
            static RetainPtr<P>& null = *(new RetainPtr<P>);
            return null;
        }
    };

    template <typename P>
    struct RetainPtrObjectHash {
        static unsigned hash(const RetainPtr<P>& o)
        {
            ASSERT_WITH_MESSAGE(o.get(), "attempt to use null RetainPtr in HashTable");
            return static_cast<unsigned>(CFHash(o.get()));
        }
        static bool equal(const RetainPtr<P>& a, const RetainPtr<P>& b)
        {
            return CFEqual(a.get(), b.get());
        }
        static const bool safeToCompareToEmptyOrDeleted = false;
    };

} // namespace WTF

using WTF::RetainPtr;
using WTF::adoptCF;
using WTF::adoptNS;
using WTF::retainPtr;

#endif // USE(CF) || defined(__OBJC__)

#endif // WTF_RetainPtr_h