base/refcnt.hh

   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
  34 class 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
  50 template <class T>
  51 class 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
  99 template<class T>
 100 bool operator==(const RefCountingPtr<T> &l, const RefCountingPtr<T> &r)
 101 { return l.get() == r.get(); }
 102
 103 template<class T>
 104 bool operator==(const RefCountingPtr<T> &l, const T *r)
 105 { return l.get() == r; }
 106
 107 template<class T>
 108 bool operator==(const T &l, const RefCountingPtr<T> &r)
 109 { return l == r.get(); }
 110
 111 template<class T>
 112 bool operator!=(const RefCountingPtr<T> &l, const RefCountingPtr<T> &r)
 113 { return l.get() != r.get(); }
 114
 115 template<class T>
 116 bool operator!=(const RefCountingPtr<T> &l, const T *r)
 117 { return l.get() != r; }
 118
 119 template<class T>
 120 bool operator!=(const T &l, const RefCountingPtr<T> &r)
 121 { return l != r.get(); }
 122
 123 #endif // __REFCNT_HH__