PublicUtility/CAAutoDisposer.h

/*
Copyright (C) 2016 Apple Inc. All Rights Reserved.
See LICENSE.txt for this sample’s licensing information
 
Abstract:
Part of Core Audio Public Utility Classes
*/
 
#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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