topical media & game development
lib-of-vs-libs-Poco-include-Poco-SharedPtr.h / h
//
// SharedPtr.h
//
//
//
// Library: Foundation
// Package: Core
// Module: SharedPtr
//
// Definition of the SharedPtr template class.
//
// Copyright (c) 2005-2008, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
//
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
ifndef Foundation_SharedPtr_INCLUDED
define Foundation_SharedPtr_INCLUDED
include "Poco/Foundation.h"
include "Poco/Exception.h"
include "Poco/Mutex.h"
include <algorithm>
namespace Poco {
class ReferenceCounter
Simple ReferenceCounter object, does not delete itself when count reaches 0.
{
public:
ReferenceCounter(): _cnt(1)
{
}
void duplicate()
{
FastMutex::ScopedLock lock(_mutex);
++_cnt;
}
int release()
{
FastMutex::ScopedLock lock(_mutex);
return --_cnt;
}
int referenceCount() const
{
return _cnt;
}
private:
FastMutex _mutex;
int _cnt;
};
template <class C>
class ReleasePolicy
The default release policy for SharedPtr, which
simply uses the delete operator to delete an object.
{
public:
static void release(C* pObj)
Delete the object.
Note that pObj can be 0.
{
delete pObj;
}
};
template <class C, class RC = ReferenceCounter, class RP = ReleasePolicy<C> >
class SharedPtr
SharedPtr is a "smart" pointer for classes implementing
reference counting based garbage collection.
SharedPtr is thus similar to AutoPtr. Unlike the
AutoPtr template, which can only be used with
classes that support reference counting, SharedPtr
can be used with any class. For this to work, a
SharedPtr manages a reference count for the object
it manages.
SharedPtr works in the following way:
If an SharedPtr is assigned an ordinary pointer to
an object (via the constructor or the assignment operator),
it takes ownership of the object and the object's reference
count is initialized to one.
If the SharedPtr is assigned another SharedPtr, the
object's reference count is incremented by one.
The destructor of SharedPtr decrements the object's
reference count by one and deletes the object if the
reference count reaches zero.
SharedPtr supports dereferencing with both the ->
and the * operator. An attempt to dereference a null
SharedPtr results in a NullPointerException being thrown.
SharedPtr also implements all relational operators and
a cast operator in case dynamic casting of the encapsulated data types
is required.
{
public:
SharedPtr(): _pCounter(new RC), _ptr(0)
{
}
SharedPtr(C* ptr): _pCounter(new RC), _ptr(ptr)
{
}
template <class Other, class OtherRP>
SharedPtr(const SharedPtr<Other, RC, OtherRP>& ptr): _pCounter(ptr._pCounter), _ptr(const_cast<Other*>(ptr.get()))
{
_pCounter->duplicate();
}
SharedPtr(const SharedPtr& ptr): _pCounter(ptr._pCounter), _ptr(ptr._ptr)
{
_pCounter->duplicate();
}
~SharedPtr()
{
release();
}
SharedPtr& assign(C* ptr)
{
if (get() != ptr)
{
RC* pTmp = new RC;
release();
_pCounter = pTmp;
_ptr = ptr;
}
return *this;
}
SharedPtr& assign(const SharedPtr& ptr)
{
if (&ptr != this)
{
SharedPtr tmp(ptr);
swap(tmp);
}
return *this;
}
template <class Other, class OtherRP>
SharedPtr& assign(const SharedPtr<Other, RC, OtherRP>& ptr)
{
if (ptr.get() != _ptr)
{
SharedPtr tmp(ptr);
swap(tmp);
}
return *this;
}
SharedPtr& operator = (C* ptr)
{
return assign(ptr);
}
SharedPtr& operator = (const SharedPtr& ptr)
{
return assign(ptr);
}
template <class Other, class OtherRP>
SharedPtr& operator = (const SharedPtr<Other, RC, OtherRP>& ptr)
{
return assign<Other>(ptr);
}
void swap(SharedPtr& ptr)
{
std::swap(_ptr, ptr._ptr);
std::swap(_pCounter, ptr._pCounter);
}
template <class Other>
SharedPtr<Other, RC, RP> cast() const
Casts the SharedPtr via a dynamic cast to the given type.
Returns an SharedPtr containing NULL if the cast fails.
Example: (assume class Sub: public Super)
SharedPtr<Super> super(new Sub());
SharedPtr<Sub> sub = super.cast<Sub>();
poco_assert (sub.get());
{
Other* pOther = dynamic_cast<Other*>(_ptr);
if (pOther)
return SharedPtr<Other, RC, RP>(_pCounter, pOther);
return SharedPtr<Other, RC, RP>();
}
template <class Other>
SharedPtr<Other, RC, RP> unsafeCast() const
Casts the SharedPtr via a static cast to the given type.
Example: (assume class Sub: public Super)
SharedPtr<Super> super(new Sub());
SharedPtr<Sub> sub = super.unsafeCast<Sub>();
poco_assert (sub.get());
{
Other* pOther = static_cast<Other*>(_ptr);
return SharedPtr<Other, RC, RP>(_pCounter, pOther);
}
C* operator -> ()
{
return deref();
}
const C* operator -> () const
{
return deref();
}
C& operator * ()
{
return *deref();
}
const C& operator * () const
{
return *deref();
}
C* get()
{
return _ptr;
}
const C* get() const
{
return _ptr;
}
operator C* ()
{
return _ptr;
}
operator const C* () const
{
return _ptr;
}
bool operator ! () const
{
return _ptr == 0;
}
bool isNull() const
{
return _ptr == 0;
}
bool operator == (const SharedPtr& ptr) const
{
return get() == ptr.get();
}
bool operator == (const C* ptr) const
{
return get() == ptr;
}
bool operator == (C* ptr) const
{
return get() == ptr;
}
bool operator != (const SharedPtr& ptr) const
{
return get() != ptr.get();
}
bool operator != (const C* ptr) const
{
return get() != ptr;
}
bool operator != (C* ptr) const
{
return get() != ptr;
}
bool operator < (const SharedPtr& ptr) const
{
return get() < ptr.get();
}
bool operator < (const C* ptr) const
{
return get() < ptr;
}
bool operator < (C* ptr) const
{
return get() < ptr;
}
bool operator <= (const SharedPtr& ptr) const
{
return get() <= ptr.get();
}
bool operator <= (const C* ptr) const
{
return get() <= ptr;
}
bool operator <= (C* ptr) const
{
return get() <= ptr;
}
bool operator > (const SharedPtr& ptr) const
{
return get() > ptr.get();
}
bool operator > (const C* ptr) const
{
return get() > ptr;
}
bool operator > (C* ptr) const
{
return get() > ptr;
}
bool operator >= (const SharedPtr& ptr) const
{
return get() >= ptr.get();
}
bool operator >= (const C* ptr) const
{
return get() >= ptr;
}
bool operator >= (C* ptr) const
{
return get() >= ptr;
}
int referenceCount() const
{
return _pCounter->referenceCount();
}
private:
C* deref() const
{
if (!_ptr)
throw NullPointerException();
return _ptr;
}
void release()
{
poco_assert_dbg (_pCounter);
int i = _pCounter->release();
if (i == 0)
{
RP::release(_ptr);
_ptr = 0;
delete _pCounter;
_pCounter = 0;
}
}
SharedPtr(RC* pCounter, C* ptr): _pCounter(pCounter), _ptr(ptr)
for cast operation
{
poco_assert_dbg (_pCounter);
_pCounter->duplicate();
}
private:
RC* _pCounter;
C* _ptr;
template <class OtherC, class OtherRC, class OtherRP> friend class SharedPtr;
};
template <class C, class RC, class RP>
inline void swap(SharedPtr<C, RC, RP>& p1, SharedPtr<C, RC, RP>& p2)
{
p1.swap(p2);
}
} // namespace Poco
endif // Foundation_SharedPtr_INCLUDED
(C) Æliens
04/09/2009
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