refcnt.hh revision 2 
1/*
2 * Copyright (c) 2003 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
32class RefCounted
33{
34  private:
35    int count;
36
37  private:
38    RefCounted(const RefCounted &);
39
40  public:
41    RefCounted() : count(0) {}
42    virtual ~RefCounted() {}
43
44    void incref() { ++count; }
45    void decref() { if (--count <= 0) delete this; }
46};
47
48template <class T>
49class RefCountingPtr
50{
51  private:
52    T *data;
53
54    void copy(T *d) {
55        data = d;
56        if (data)
57            data->incref();
58    }
59    void del() {
60        if (data)
61            data->decref();
62    }
63
64  public:
65    RefCountingPtr() : data(NULL) {}
66    RefCountingPtr(T *data) { copy(data); }
67    RefCountingPtr(const RefCountingPtr& r) { copy(r.data); }
68    ~RefCountingPtr() { del(); }
69
70    T *operator->() { return data; }
71    T &operator*() { return *data; }
72    T *get() { return data; }
73
74    const T *operator->() const { return data; }
75    const T &operator*() const { return *data; }
76    const T *get() const { return data; }
77
78    RefCountingPtr &operator=(T *p) {
79        if (data != p) {
80            del();
81            copy(p);
82        }
83        return *this;
84    }
85
86    RefCountingPtr &operator=(const RefCountingPtr& r) {
87        if (data != r.data) {
88            del();
89            copy(r.data);
90        }
91        return *this;
92    }
93
94    bool operator!() const { return data == 0; }
95    operator bool() const { return data != 0; }
96};
97
98template<class T>
99bool operator==(const RefCountingPtr<T> &l, const RefCountingPtr<T> &r)
100{ return l.get() == r.get(); }
101
102template<class T>
103bool operator==(const RefCountingPtr<T> &l, const T *r)
104{ return l.get() == r; }
105
106template<class T>
107bool operator==(const T &l, const RefCountingPtr<T> &r)
108{ return l == r.get(); }
109
110template<class T>
111bool operator!=(const RefCountingPtr<T> &l, const RefCountingPtr<T> &r)
112{ return l.get() != r.get(); }
113
114template<class T>
115bool operator!=(const RefCountingPtr<T> &l, const T *r)
116{ return l.get() != r; }
117
118template<class T>
119bool operator!=(const T &l, const RefCountingPtr<T> &r)
120{ return l != r.get(); }
121
122#endif // __REFCNT_HH__
123