3 * Copyright 2004--2005, Google Inc.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
8 * 1. Redistributions of source code must retain the above copyright notice,
9 * this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright notice,
11 * this list of conditions and the following disclaimer in the documentation
12 * and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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29 * linked_ptr - simple reference linked pointer
30 * (like reference counting, just using a linked list of the references
31 * instead of their count.)
33 * The implementation stores three pointers for every linked_ptr, but
34 * does not allocate anything on the free store.
37 #ifndef TALK_BASE_LINKED_PTR_H__
38 #define TALK_BASE_LINKED_PTR_H__
42 /* For ANSI-challenged compilers, you may want to #define
43 * NO_MEMBER_TEMPLATES, explicit or mutable */
44 #define NO_MEMBER_TEMPLATES
46 template <class X> class linked_ptr
50 #ifndef NO_MEMBER_TEMPLATES
51 # define TEMPLATE_FUNCTION template <class Y>
52 TEMPLATE_FUNCTION friend class linked_ptr<Y>;
54 # define TEMPLATE_FUNCTION
58 typedef X element_type;
60 explicit linked_ptr(X* p = 0) throw()
61 : itsPtr(p) {itsPrev = itsNext = this;}
64 linked_ptr(const linked_ptr& r) throw()
66 linked_ptr& operator=(const linked_ptr& r)
75 #ifndef NO_MEMBER_TEMPLATES
76 template <class Y> friend class linked_ptr<Y>;
77 template <class Y> linked_ptr(const linked_ptr<Y>& r) throw()
79 template <class Y> linked_ptr& operator=(const linked_ptr<Y>& r)
87 #endif // NO_MEMBER_TEMPLATES
89 X& operator*() const throw() {return *itsPtr;}
90 X* operator->() const throw() {return itsPtr;}
91 X* get() const throw() {return itsPtr;}
92 bool unique() const throw() {return itsPrev ? itsPrev==this : true;}
96 mutable const linked_ptr* itsPrev;
97 mutable const linked_ptr* itsNext;
99 void acquire(const linked_ptr& r) throw()
100 { // insert this to the list
103 itsNext->itsPrev = this;
107 #else // for ANSI-challenged compilers
108 (const_cast<linked_ptr<X>*>(&r))->itsNext = this;
112 #ifndef NO_MEMBER_TEMPLATES
113 template <class Y> void acquire(const linked_ptr<Y>& r) throw()
114 { // insert this to the list
117 itsNext->itsPrev = this;
121 #else // for ANSI-challenged compilers
122 (const_cast<linked_ptr<X>*>(&r))->itsNext = this;
125 #endif // NO_MEMBER_TEMPLATES
128 { // erase this from the list, delete if unique
129 if (unique()) delete itsPtr;
131 itsPrev->itsNext = itsNext;
132 itsNext->itsPrev = itsPrev;
133 itsPrev = itsNext = 0;
139 } // namespace talk_base
141 #endif // TALK_BASE_LINKED_PTR_H__