28e2075280
trunk/talk git-svn-id: http://webrtc.googlecode.com/svn/trunk@4318 4adac7df-926f-26a2-2b94-8c16560cd09d
143 lines
4.4 KiB
C++
143 lines
4.4 KiB
C++
/*
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* libjingle
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* Copyright 2004--2005, Google Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* linked_ptr - simple reference linked pointer
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* (like reference counting, just using a linked list of the references
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* instead of their count.)
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*
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* The implementation stores three pointers for every linked_ptr, but
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* does not allocate anything on the free store.
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*/
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#ifndef TALK_BASE_LINKED_PTR_H__
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#define TALK_BASE_LINKED_PTR_H__
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namespace talk_base {
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/* For ANSI-challenged compilers, you may want to #define
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* NO_MEMBER_TEMPLATES, explicit or mutable */
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#define NO_MEMBER_TEMPLATES
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template <class X> class linked_ptr
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{
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public:
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#ifndef NO_MEMBER_TEMPLATES
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# define TEMPLATE_FUNCTION template <class Y>
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TEMPLATE_FUNCTION friend class linked_ptr<Y>;
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#else
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# define TEMPLATE_FUNCTION
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typedef X Y;
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#endif
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typedef X element_type;
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explicit linked_ptr(X* p = 0) throw()
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: itsPtr(p) {itsPrev = itsNext = this;}
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~linked_ptr()
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{release();}
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linked_ptr(const linked_ptr& r) throw()
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{acquire(r);}
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linked_ptr& operator=(const linked_ptr& r)
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{
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if (this != &r) {
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release();
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acquire(r);
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}
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return *this;
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}
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#ifndef NO_MEMBER_TEMPLATES
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template <class Y> friend class linked_ptr<Y>;
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template <class Y> linked_ptr(const linked_ptr<Y>& r) throw()
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{acquire(r);}
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template <class Y> linked_ptr& operator=(const linked_ptr<Y>& r)
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{
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if (this != &r) {
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release();
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acquire(r);
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}
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return *this;
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}
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#endif // NO_MEMBER_TEMPLATES
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X& operator*() const throw() {return *itsPtr;}
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X* operator->() const throw() {return itsPtr;}
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X* get() const throw() {return itsPtr;}
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bool unique() const throw() {return itsPrev ? itsPrev==this : true;}
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private:
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X* itsPtr;
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mutable const linked_ptr* itsPrev;
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mutable const linked_ptr* itsNext;
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void acquire(const linked_ptr& r) throw()
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{ // insert this to the list
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itsPtr = r.itsPtr;
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itsNext = r.itsNext;
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itsNext->itsPrev = this;
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itsPrev = &r;
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#ifndef mutable
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r.itsNext = this;
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#else // for ANSI-challenged compilers
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(const_cast<linked_ptr<X>*>(&r))->itsNext = this;
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#endif
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}
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#ifndef NO_MEMBER_TEMPLATES
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template <class Y> void acquire(const linked_ptr<Y>& r) throw()
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{ // insert this to the list
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itsPtr = r.itsPtr;
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itsNext = r.itsNext;
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itsNext->itsPrev = this;
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itsPrev = &r;
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#ifndef mutable
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r.itsNext = this;
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#else // for ANSI-challenged compilers
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(const_cast<linked_ptr<X>*>(&r))->itsNext = this;
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#endif
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}
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#endif // NO_MEMBER_TEMPLATES
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void release()
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{ // erase this from the list, delete if unique
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if (unique()) delete itsPtr;
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else {
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itsPrev->itsNext = itsNext;
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itsNext->itsPrev = itsPrev;
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itsPrev = itsNext = 0;
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}
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itsPtr = 0;
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}
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};
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} // namespace talk_base
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#endif // TALK_BASE_LINKED_PTR_H__
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