refcnt.hh revision 2147 
1/*
2 * Copyright (c) 2002-2005 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef __REFCNT_HH__
30#define __REFCNT_HH__
31
32#include <stddef.h> //For the NULL macro definition
33
34class RefCounted
35{
36  private:
37    int count;
38
39  private:
40    RefCounted(const RefCounted &);
41
42  public:
43    RefCounted() : count(0) {}
44    virtual ~RefCounted() {}
45
46    void incref() { ++count; }
47    void decref() { if (--count <= 0) delete this; }
48};
49
50template <class T>
51class RefCountingPtr
52{
53  protected:
54    T *data;
55
56    void copy(T *d)
57    {
58        data = d;
59        if (data)
60            data->incref();
61    }
62    void del()
63    {
64        if (data)
65            data->decref();
66    }
67    void set(T *d)
68    {
69        if (data == d)
70            return;
71
72        del();
73        copy(d);
74    }
75
76
77  public:
78    RefCountingPtr() : data(NULL) {}
79    RefCountingPtr(T *data) { copy(data); }
80    RefCountingPtr(const RefCountingPtr &r) { copy(r.data); }
81    ~RefCountingPtr() { del(); }
82
83    T *operator->() { return data; }
84    T &operator*() { return *data; }
85    T *get() { return data; }
86
87    const T *operator->() const { return data; }
88    const T &operator*() const { return *data; }
89    const T *get() const { return data; }
90
91    RefCountingPtr &operator=(T *p) { set(p); return *this; }
92    RefCountingPtr &operator=(const RefCountingPtr &r)
93    { return operator=(r.data); }
94
95    bool operator!() const { return data == 0; }
96    operator bool() const { return data != 0; }
97};
98
99template<class T>
100bool operator==(const RefCountingPtr<T> &l, const RefCountingPtr<T> &r)
101{ return l.get() == r.get(); }
102
103template<class T>
104bool operator==(const RefCountingPtr<T> &l, const T *r)
105{ return l.get() == r; }
106
107template<class T>
108bool operator==(const T &l, const RefCountingPtr<T> &r)
109{ return l == r.get(); }
110
111template<class T>
112bool operator!=(const RefCountingPtr<T> &l, const RefCountingPtr<T> &r)
113{ return l.get() != r.get(); }
114
115template<class T>
116bool operator!=(const RefCountingPtr<T> &l, const T *r)
117{ return l.get() != r; }
118
119template<class T>
120bool operator!=(const T &l, const RefCountingPtr<T> &r)
121{ return l != r.get(); }
122
123#endif // __REFCNT_HH__
124