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Retired Document

Important: This sample code may not represent best practices for current development. The project may use deprecated symbols and illustrate technologies and techniques that are no longer recommended.

Relevant replacement documents include:

http://developer.apple.com/library/mac/samplecode/sc2195/Introduction/Intro.html#//apple_ref/doc/uid/DTS40013969

PublicUtility/CAAutoDisposer.h

/*

     File: CAAutoDisposer.h

 Abstract: Part of CoreAudio Utility Classes

  Version: 1.1

 Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple

 Inc. ("Apple") in consideration of your agreement to the following

 terms, and your use, installation, modification or redistribution of

 this Apple software constitutes acceptance of these terms.  If you do

 not agree with these terms, please do not use, install, modify or

 redistribute this Apple software.

 In consideration of your agreement to abide by the following terms, and

 subject to these terms, Apple grants you a personal, non-exclusive

 license, under Apple's copyrights in this original Apple software (the

 "Apple Software"), to use, reproduce, modify and redistribute the Apple

 Software, with or without modifications, in source and/or binary forms;

 provided that if you redistribute the Apple Software in its entirety and

 without modifications, you must retain this notice and the following

 text and disclaimers in all such redistributions of the Apple Software.

 Neither the name, trademarks, service marks or logos of Apple Inc. may

 be used to endorse or promote products derived from the Apple Software

 without specific prior written permission from Apple.  Except as

 expressly stated in this notice, no other rights or licenses, express or

 implied, are granted by Apple herein, including but not limited to any

 patent rights that may be infringed by your derivative works or by other

 works in which the Apple Software may be incorporated.

 The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

 THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS

 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL

 OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,

 MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED

 AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),

 STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE

 POSSIBILITY OF SUCH DAMAGE.

 Copyright (C) 2012 Apple Inc. All Rights Reserved.

*/

#if !defined(__CAPtr_h__)

#define __CAPtr_h__

#include <stdlib.h>     // for malloc

#include <new>          // for bad_alloc

#include <string.h>     // for memset

inline void* CA_malloc(size_t size)

    void* p = malloc(size);

    if (!p && size) throw std::bad_alloc();

    return p;

inline void* CA_realloc(void* old, size_t size)

#if TARGET_OS_WIN32

    void* p = realloc(old, size);

#else

    void* p = reallocf(old, size); // reallocf ensures the old pointer is freed if memory is full (p is NULL).

#endif

    if (!p && size) throw std::bad_alloc();

    return p;

#ifndef UINTPTR_MAX

#if __LP64__

#define UINTPTR_MAX   18446744073709551615ULL

#else

#define UINTPTR_MAX   4294967295U

#endif

#endif

inline void* CA_calloc(size_t n, size_t size)

    // ensure that multiplication will not overflow

    if (n && UINTPTR_MAX / n < size) throw std::bad_alloc();

    size_t nsize = n*size;

    void* p = malloc(nsize);

    if (!p && nsize) throw std::bad_alloc();

    memset(p, 0, nsize);

    return p;

// helper class for automatic conversions

template <typename T>

struct CAPtrRef

    T* ptr_;

    explicit CAPtrRef(T* ptr) : ptr_(ptr) {}

};

template <typename T>

class CAAutoFree

private:

    T* ptr_;

public:

    CAAutoFree() : ptr_(0) {}

    explicit CAAutoFree(T* ptr) : ptr_(ptr) {}

    template<typename U>

    CAAutoFree(CAAutoFree<U>& that) : ptr_(that.release()) {} // take ownership

    // C++ std says: a template constructor is never a copy constructor

    CAAutoFree(CAAutoFree<T>& that) : ptr_(that.release()) {} // take ownership

    CAAutoFree(size_t n, bool clear = false)

        // this becomes an ambiguous call if n == 0

        : ptr_(0)

            size_t maxItems = ~size_t(0) / sizeof(T);

            if (n > maxItems)

                throw std::bad_alloc();

            ptr_ = static_cast<T*>(clear ? CA_calloc(n, sizeof(T)) : CA_malloc(n * sizeof(T)));

    ~CAAutoFree() { free(); }

    void alloc(size_t numItems, bool clear = false)

        size_t maxItems = ~size_t(0) / sizeof(T);

        if (numItems > maxItems) throw std::bad_alloc();

        free();

        ptr_ = static_cast<T*>(clear ? CA_calloc(numItems, sizeof(T)) : CA_malloc(numItems * sizeof(T)));

    void allocBytes(size_t numBytes, bool clear = false)

        free();

        ptr_ = static_cast<T*>(clear ? CA_calloc(1, numBytes) : CA_malloc(numBytes));

    void reallocBytes(size_t numBytes)

        ptr_ = static_cast<T*>(CA_realloc(ptr_, numBytes));

    void reallocItems(size_t numItems)

        size_t maxItems = ~size_t(0) / sizeof(T);

        if (numItems > maxItems) throw std::bad_alloc();

        ptr_ = static_cast<T*>(CA_realloc(ptr_, numItems * sizeof(T)));

    template <typename U>

    CAAutoFree& operator=(CAAutoFree<U>& that)

        set(that.release());    // take ownership

        return *this;

    CAAutoFree& operator=(CAAutoFree& that)

        set(that.release());    // take ownership

        return *this;

    CAAutoFree& operator=(T* ptr)

        set(ptr);

        return *this;

    template <typename U>

    CAAutoFree& operator=(U* ptr)

        set(ptr);

        return *this;

    T& operator*() const { return *ptr_; }

    T* operator->() const { return ptr_; }

    T* operator()() const { return ptr_; }

    T* get() const { return ptr_; }

    operator T*() const { return ptr_; }

    bool operator==(CAAutoFree const& that) const { return ptr_ == that.ptr_; }

    bool operator!=(CAAutoFree const& that) const { return ptr_ != that.ptr_; }

    bool operator==(T* ptr) const { return ptr_ == ptr; }

    bool operator!=(T* ptr) const { return ptr_ != ptr; }

    T* release()

        // release ownership

        T* result = ptr_;

        ptr_ = 0;

        return result;

    void set(T* ptr)

        if (ptr != ptr_)

            ::free(ptr_);

            ptr_ = ptr;

    void free()

        set(0);

    // automatic conversions to allow assignment from results of functions.

    // hard to explain. see auto_ptr implementation and/or Josuttis' STL book.

    CAAutoFree(CAPtrRef<T> ref) : ptr_(ref.ptr_) { }

    CAAutoFree& operator=(CAPtrRef<T> ref)

        set(ref.ptr_);

        return *this;

    template<typename U>

    operator CAPtrRef<U>()

        { return CAPtrRef<U>(release()); }

    template<typename U>

    operator CAAutoFree<U>()

        { return CAAutoFree<U>(release()); }

};

template <typename T>

class CAAutoDelete

private:

    T* ptr_;

public:

    CAAutoDelete() : ptr_(0) {}

    explicit CAAutoDelete(T* ptr) : ptr_(ptr) {}

    template<typename U>

    CAAutoDelete(CAAutoDelete<U>& that) : ptr_(that.release()) {} // take ownership

    // C++ std says: a template constructor is never a copy constructor

    CAAutoDelete(CAAutoDelete<T>& that) : ptr_(that.release()) {} // take ownership

    ~CAAutoDelete() { free(); }

    template <typename U>

    CAAutoDelete& operator=(CAAutoDelete<U>& that)

        set(that.release());    // take ownership

        return *this;

    CAAutoDelete& operator=(CAAutoDelete& that)

        set(that.release());    // take ownership

        return *this;

    CAAutoDelete& operator=(T* ptr)

        set(ptr);

        return *this;

    template <typename U>

    CAAutoDelete& operator=(U* ptr)

        set(ptr);

        return *this;

    T& operator*() const { return *ptr_; }

    T* operator->() const { return ptr_; }

    T* operator()() const { return ptr_; }

    T* get() const { return ptr_; }

    operator T*() const { return ptr_; }

    bool operator==(CAAutoDelete const& that) const { return ptr_ == that.ptr_; }

    bool operator!=(CAAutoDelete const& that) const { return ptr_ != that.ptr_; }

    bool operator==(T* ptr) const { return ptr_ == ptr; }

    bool operator!=(T* ptr) const { return ptr_ != ptr; }

    T* release()

        // release ownership

        T* result = ptr_;

        ptr_ = 0;

        return result;

    void set(T* ptr)

        if (ptr != ptr_)

            delete ptr_;

            ptr_ = ptr;

    void free()

        set(0);

    // automatic conversions to allow assignment from results of functions.

    // hard to explain. see auto_ptr implementation and/or Josuttis' STL book.

    CAAutoDelete(CAPtrRef<T> ref) : ptr_(ref.ptr_) { }

    CAAutoDelete& operator=(CAPtrRef<T> ref)

        set(ref.ptr_);

        return *this;

    template<typename U>

    operator CAPtrRef<U>()

        { return CAPtrRef<U>(release()); }

    template<typename U>

    operator CAAutoFree<U>()

        { return CAAutoFree<U>(release()); }

};

template <typename T>

class CAAutoArrayDelete

private:

    T* ptr_;

public:

    CAAutoArrayDelete() : ptr_(0) {}

    explicit CAAutoArrayDelete(T* ptr) : ptr_(ptr) {}

    template<typename U>

    CAAutoArrayDelete(CAAutoArrayDelete<U>& that) : ptr_(that.release()) {} // take ownership

    // C++ std says: a template constructor is never a copy constructor

    CAAutoArrayDelete(CAAutoArrayDelete<T>& that) : ptr_(that.release()) {} // take ownership

    // this becomes an ambiguous call if n == 0

    CAAutoArrayDelete(size_t n) : ptr_(new T[n]) {}

    ~CAAutoArrayDelete() { free(); }

    void alloc(size_t numItems)

        free();

        ptr_ = new T [numItems];

    template <typename U>

    CAAutoArrayDelete& operator=(CAAutoArrayDelete<U>& that)

        set(that.release());    // take ownership

        return *this;

    CAAutoArrayDelete& operator=(CAAutoArrayDelete& that)

        set(that.release());    // take ownership

        return *this;

    CAAutoArrayDelete& operator=(T* ptr)

        set(ptr);

        return *this;

    template <typename U>

    CAAutoArrayDelete& operator=(U* ptr)

        set(ptr);

        return *this;

    T& operator*() const { return *ptr_; }

    T* operator->() const { return ptr_; }

    T* operator()() const { return ptr_; }

    T* get() const { return ptr_; }

    operator T*() const { return ptr_; }

    bool operator==(CAAutoArrayDelete const& that) const { return ptr_ == that.ptr_; }

    bool operator!=(CAAutoArrayDelete const& that) const { return ptr_ != that.ptr_; }

    bool operator==(T* ptr) const { return ptr_ == ptr; }

    bool operator!=(T* ptr) const { return ptr_ != ptr; }

    T* release()

        // release ownership

        T* result = ptr_;

        ptr_ = 0;

        return result;

    void set(T* ptr)

        if (ptr != ptr_)

            delete [] ptr_;

            ptr_ = ptr;

    void free()

        set(0);

    // automatic conversions to allow assignment from results of functions.

    // hard to explain. see auto_ptr implementation and/or Josuttis' STL book.

    CAAutoArrayDelete(CAPtrRef<T> ref) : ptr_(ref.ptr_) { }

    CAAutoArrayDelete& operator=(CAPtrRef<T> ref)

        set(ref.ptr_);

        return *this;

    template<typename U>

    operator CAPtrRef<U>()

        { return CAPtrRef<U>(release()); }

    template<typename U>

    operator CAAutoArrayDelete<U>()

        { return CAAutoFree<U>(release()); }

};

// convenience function

template <typename T>

void free(CAAutoFree<T>& p)

    p.free();

////////////////////////////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////////////////////////////

#if 0

// example program showing ownership transfer

CAAutoFree<char> source()

    // source allocates and returns ownership to the caller.

    const char* str = "this is a test";

    size_t size = strlen(str) + 1;

    CAAutoFree<char> captr(size, false);

    strlcpy(captr(), str, size);

    printf("source %08X %08X '%s'\n", &captr, captr(), captr());

    return captr;

void user(CAAutoFree<char> const& captr)

    // passed by const reference. user can access the pointer but does not take ownership.

    printf("user: %08X %08X '%s'\n", &captr, captr(), captr());

void sink(CAAutoFree<char> captr)

    // passed by value. sink takes ownership and frees the pointer on return.

    printf("sink: %08X %08X '%s'\n", &captr, captr(), captr());

int main (int argc, char * const argv[])

    CAAutoFree<char> captr(source());

    printf("main captr A %08X %08X\n", &captr, captr());

    user(captr);

    sink(captr);

    printf("main captr B %08X %08X\n", &captr, captr());

    return 0;

#endif

#endif

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