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// Copyright (C) 2003 Davis E. King (davis@dlib.net)
// License: Boost Software License See LICENSE.txt for the full license.
#ifndef DLIB_REFERENCE_COUNTER_KERNEl_1_
#define DLIB_REFERENCE_COUNTER_KERNEl_1_
#include "reference_counter_kernel_abstract.h"
#include "../algs.h"
namespace dlib
{
template <
typename T,
typename copy = copy_functor<T>
>
class reference_counter_kernel_1
{
/*!
INITIAL VALUE
*data = item of type T with its initial value
*count = 1
CONVENTION
*data = pointer to item of type T
*count = number of references to *data
if clear() threw an exception then count = 0 and data is not a
valid pointer
!*/
public:
typedef T type;
reference_counter_kernel_1 (
);
inline reference_counter_kernel_1 (
const reference_counter_kernel_1& item
);
virtual ~reference_counter_kernel_1 (
);
void clear (
);
T& modify (
);
inline const T& access (
) const;
inline reference_counter_kernel_1& operator= (
const reference_counter_kernel_1& rhs
);
inline void swap (
reference_counter_kernel_1& item
);
private:
T* data;
unsigned long* count;
mutable copy copy_item;
};
template <
typename T,
typename copy
>
inline void swap (
reference_counter_kernel_1<T,copy>& a,
reference_counter_kernel_1<T,copy>& b
) { a.swap(b); }
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
// member function definitions
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
template <
typename T,
typename copy
>
reference_counter_kernel_1<T,copy>::
reference_counter_kernel_1 (
)
{
data = new T;
try { count = new unsigned long; }
catch (...) { delete data; throw; }
*count = 1;
}
// ----------------------------------------------------------------------------------------
template <
typename T,
typename copy
>
reference_counter_kernel_1<T,copy>::
reference_counter_kernel_1 (
const reference_counter_kernel_1<T,copy>& item
) :
data(item.data),
count(item.count)
{
++(*count);
}
// ----------------------------------------------------------------------------------------
template <
typename T,
typename copy
>
reference_counter_kernel_1<T,copy>::
~reference_counter_kernel_1 (
)
{
if (*count > 1)
{
// if there are other references to this data
--(*count);
}
else
{
// if there are no other references to this data
delete count;
delete data;
}
}
// ----------------------------------------------------------------------------------------
template <
typename T,
typename copy
>
void reference_counter_kernel_1<T,copy>::
clear (
)
{
// if an exception was thrown last time clear() was called then do this
if (count == 0)
{
data = new T;
try { count = new unsigned long; }
catch (...) { delete data; throw; }
*count = 1;
}
// if there are other references to the data then do this
else if (*count > 1)
{
--(*count);
try { data = new T; }
catch (...) { count = 0; throw; }
try { count = new unsigned long; }
catch (...) { delete data; count = 0; throw; }
*count = 1;
}
else
{
// if there are no other references to this data
*count = 1;
delete data;
try { data = new T; } catch (...) { delete count; count = 0; throw; }
}
}
// ----------------------------------------------------------------------------------------
template <
typename T,
typename copy
>
T& reference_counter_kernel_1<T,copy>::
modify (
)
{
// if this is not the only reference then make a new copy
if ( *count > 1 )
{
T& old_data = *data;
unsigned long& old_count = *count;
// get memory for the new copy
try { data = new T; }
catch (...) { data = &old_data; throw; }
try { count = new unsigned long; }
catch (...) {delete data; data = &old_data; count = &old_count; throw;}
// decrement the number of references to old_data
--(old_count);
*count = 1;
// make a copy of the old data
try { copy_item(old_data,*data); }
catch (...)
{ delete data; delete count; data = &old_data; count = &old_count; }
}
return *data;
}
// ----------------------------------------------------------------------------------------
template <
typename T,
typename copy
>
const T& reference_counter_kernel_1<T,copy>::
access (
) const
{
return *data;
}
// ----------------------------------------------------------------------------------------
template <
typename T,
typename copy
>
reference_counter_kernel_1<T,copy>& reference_counter_kernel_1<T,copy>::
operator= (
const reference_counter_kernel_1<T,copy>& rhs
)
{
if (this == &rhs)
return *this;
// delete the current data if this is the last reference to it
if (*count > 1)
{
// if there are other references to this data
--(*count);
}
else
{
// if there are no other references to this data
delete count;
delete data;
}
// copy the pointers
count = (rhs.count);
data = (rhs.data);
++(*count);
return *this;
}
// ----------------------------------------------------------------------------------------
template <
typename T,
typename copy
>
void reference_counter_kernel_1<T,copy>::
swap (
reference_counter_kernel_1<T,copy>& item
)
{
T* data_temp = data;
unsigned long* count_temp = count;
data = item.data;
count = item.count;
item.data = data_temp;
item.count = count_temp;
}
// ----------------------------------------------------------------------------------------
}
#endif // DLIB_REFERENCE_COUNTER_KERNEl_1_
|
