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/*
** ClanLib SDK
** Copyright (c) 1997-2005 The ClanLib Team
**
** This software is provided 'as-is', without any express or implied
** warranty. In no event will the authors be held liable for any damages
** arising from the use of this software.
**
** Permission is granted to anyone to use this software for any purpose,
** including commercial applications, and to alter it and redistribute it
** freely, subject to the following restrictions:
**
** 1. The origin of this software must not be misrepresented; you must not
** claim that you wrote the original software. If you use this software
** in a product, an acknowledgment in the product documentation would be
** appreciated but is not required.
** 2. Altered source versions must be plainly marked as such, and must not be
** misrepresented as being the original software.
** 3. This notice may not be removed or altered from any source distribution.
**
** Note: Some of the libraries ClanLib may link to may have additional
** requirements or restrictions.
**
** File Author(s):
**
** Magnus Norddahl
** (if your name is missing here, please add it)
*/
//! clanCore="System"
//! header=core.h
#ifndef clanlib_weakptr_header
#define clanlib_weakptr_header
#include "sharedptr.h"
//: Weak pointer class (pointer to a CL_SharedPtr object that dont increase reference count).
//- !group=Core/System!
//- !header=core.h!
//- <p>Use CL_WeakPtr when you want to have a pointer that is reference counted by CL_SharedPtr
//- but want a pointer that dont increase the reference count.</p>
//- <p>The purpose of CL_WeakPtr is to avoid circular loop issues. By using CL_WeakPtr you
//- can construct new CL_SharedPtr'ed objects based on the weak pointer.</p>
template <typename T, typename U = T>
class CL_WeakPtr
{
//! Construction:
public:
CL_WeakPtr() : impl(0) { return; }
CL_WeakPtr(CL_SharedPtr<T, U> &other) : impl(other.get_impl()) { return; }
//! Operations:
public:
//: Returns true if this CL_SharedPtr is not dereferencable.
bool is_null() const { return impl ? (impl->ptr == 0) : true; }
//: Returns number of references (including this one) to the data cache.
//- <p> Returns 0 if this pointer is null. </p>
int get_ref_count() const { if (impl == 0) return 0; return impl->ref_count; }
//: Gives access to the pointer itself.
//- <p> Be careful not to keep the returned pointer around after doing any
//- non-const operations on the CL_LazyCopyPtr; it could be invalid
//- after that.</p>
U* get() { return (U*) ((impl != 0) ? impl->ptr : 0); }
const U* get() const { return (const U*) ((impl != 0) ? impl->ptr : 0); }
//: Returns the pointer.
operator const U*() const { return get(); }
//: Returns the pointer as a shared ptr.
operator CL_SharedPtr<T, U>() const { return CL_SharedPtr<T, U>(impl); }
//: Dereferencing operator.
U& operator*() { return *((U*) impl->ptr); }
U const& operator*() const { return *((const U*) impl->ptr); }
//: Indirect member access operator.
U* operator->() { return (U*) impl->ptr; }
U const* operator->() const { return (const U*) impl->ptr; }
//: Pointer equality check operator.
//- <p> This will return true if the CL_SharedPtrs point to the same data. It doesn't
//- check the data itself for equality. </p>
bool operator==(const T* other) const { return other == ((impl != 0) ? impl->ptr : 0); }
bool operator==(const CL_SharedPtr<T, U>& other) const { return other.impl == impl; }
//! Implementation:
private:
CL_SharedPtr_Generic<T> *impl;
};
#endif
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