callback.hh revision 1094 
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 __CALLBACK_HH__
30#define __CALLBACK_HH__
31
32#include <list>
33
34/**
35 * Generic callback class.  This base class provides a virutal process
36 * function that gets called when the callback queue is processed.
37 */
38class Callback
39{
40  public:
41    /**
42     * virtualize the destructor to make sure that the correct one
43     * gets called.
44     */
45    virtual ~Callback() {}
46
47    /**
48     * virtual process function that is invoked when the callback
49     * queue is executed.
50     */
51    virtual void process() = 0;
52};
53
54class CallbackQueue
55{
56  protected:
57    /**
58     * Simple typedef for the data structure that stores all of the
59     * callbacks.
60     */
61    typedef std::list<Callback *> queue;
62
63    /**
64     * List of all callbacks.  To be called in fifo order.
65     */
66    queue callbacks;
67
68  public:
69    /**
70     * Add a callback to the end of the queue
71     * @param callback the callback to be added to the queue
72     */
73    void add(Callback *callback)
74    {
75        callbacks.push_back(callback);
76    }
77
78    /**
79     * Find out if there are any callbacks in the queue
80     */
81    bool empty() const { return callbacks.empty(); }
82
83    /**
84     * process all callbacks
85     */
86    void process()
87    {
88        queue::iterator i = callbacks.begin();
89        queue::iterator end = callbacks.end();
90
91        while (i != end) {
92            (*i)->process();
93            ++i;
94        }
95    }
96
97    /**
98     * clear the callback queue
99     */
100    void clear()
101    {
102        callbacks.clear();
103    }
104};
105
106template <class T, void (T::* F)()>
107class MakeCallback : public Callback
108{
109  private:
110    T *object;
111
112  public:
113    MakeCallback(T *o)
114    : object(o)
115    { }
116    void process() { (object->*F)(); }
117};
118
119#endif // __CALLBACK_HH__
120