126 lines
3.3 KiB
C++
126 lines
3.3 KiB
C++
/*
|
|
* Copyright 2004 The WebRTC Project Authors. All rights reserved.
|
|
*
|
|
* Use of this source code is governed by a BSD-style license
|
|
* that can be found in the LICENSE file in the root of the source
|
|
* tree. An additional intellectual property rights grant can be found
|
|
* in the file PATENTS. All contributing project authors may
|
|
* be found in the AUTHORS file in the root of the source tree.
|
|
*/
|
|
|
|
/*
|
|
* linked_ptr - simple reference linked pointer
|
|
* (like reference counting, just using a linked list of the references
|
|
* instead of their count.)
|
|
*
|
|
* The implementation stores three pointers for every linked_ptr, but
|
|
* does not allocate anything on the free store.
|
|
*/
|
|
|
|
#ifndef WEBRTC_BASE_LINKED_PTR_H__
|
|
#define WEBRTC_BASE_LINKED_PTR_H__
|
|
|
|
namespace rtc {
|
|
|
|
/* For ANSI-challenged compilers, you may want to #define
|
|
* NO_MEMBER_TEMPLATES, explicit or mutable */
|
|
#define NO_MEMBER_TEMPLATES
|
|
|
|
template <class X> class linked_ptr
|
|
{
|
|
public:
|
|
|
|
#ifndef NO_MEMBER_TEMPLATES
|
|
# define TEMPLATE_FUNCTION template <class Y>
|
|
TEMPLATE_FUNCTION friend class linked_ptr<Y>;
|
|
#else
|
|
# define TEMPLATE_FUNCTION
|
|
typedef X Y;
|
|
#endif
|
|
|
|
typedef X element_type;
|
|
|
|
explicit linked_ptr(X* p = 0) throw()
|
|
: itsPtr(p) {itsPrev = itsNext = this;}
|
|
~linked_ptr()
|
|
{release();}
|
|
linked_ptr(const linked_ptr& r) throw()
|
|
{acquire(r);}
|
|
linked_ptr& operator=(const linked_ptr& r)
|
|
{
|
|
if (this != &r) {
|
|
release();
|
|
acquire(r);
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
#ifndef NO_MEMBER_TEMPLATES
|
|
template <class Y> friend class linked_ptr<Y>;
|
|
template <class Y> linked_ptr(const linked_ptr<Y>& r) throw()
|
|
{acquire(r);}
|
|
template <class Y> linked_ptr& operator=(const linked_ptr<Y>& r)
|
|
{
|
|
if (this != &r) {
|
|
release();
|
|
acquire(r);
|
|
}
|
|
return *this;
|
|
}
|
|
#endif // NO_MEMBER_TEMPLATES
|
|
|
|
X& operator*() const throw() {return *itsPtr;}
|
|
X* operator->() const throw() {return itsPtr;}
|
|
X* get() const throw() {return itsPtr;}
|
|
bool unique() const throw() {return itsPrev ? itsPrev==this : true;}
|
|
|
|
private:
|
|
X* itsPtr;
|
|
mutable const linked_ptr* itsPrev;
|
|
mutable const linked_ptr* itsNext;
|
|
|
|
void acquire(const linked_ptr& r) throw()
|
|
{ // insert this to the list
|
|
itsPtr = r.itsPtr;
|
|
itsNext = r.itsNext;
|
|
itsNext->itsPrev = this;
|
|
itsPrev = &r;
|
|
#ifndef mutable
|
|
r.itsNext = this;
|
|
#else // for ANSI-challenged compilers
|
|
(const_cast<linked_ptr<X>*>(&r))->itsNext = this;
|
|
#endif
|
|
}
|
|
|
|
#ifndef NO_MEMBER_TEMPLATES
|
|
template <class Y> void acquire(const linked_ptr<Y>& r) throw()
|
|
{ // insert this to the list
|
|
itsPtr = r.itsPtr;
|
|
itsNext = r.itsNext;
|
|
itsNext->itsPrev = this;
|
|
itsPrev = &r;
|
|
#ifndef mutable
|
|
r.itsNext = this;
|
|
#else // for ANSI-challenged compilers
|
|
(const_cast<linked_ptr<X>*>(&r))->itsNext = this;
|
|
#endif
|
|
}
|
|
#endif // NO_MEMBER_TEMPLATES
|
|
|
|
void release()
|
|
{ // erase this from the list, delete if unique
|
|
if (unique()) delete itsPtr;
|
|
else {
|
|
itsPrev->itsNext = itsNext;
|
|
itsNext->itsPrev = itsPrev;
|
|
itsPrev = itsNext = 0;
|
|
}
|
|
itsPtr = 0;
|
|
}
|
|
};
|
|
|
|
} // namespace rtc
|
|
|
|
#endif // WEBRTC_BASE_LINKED_PTR_H__
|
|
|