base/refcnt.hh

   1 /*
   2  * Copyright (c) 2002-2004 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 class 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
  48 template <class T>
  49 class RefCountingPtr
  50 {
  51   protected:
  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
  98 template<class T>
  99 bool operator==(const RefCountingPtr<T> &l, const RefCountingPtr<T> &r)
 100 { return l.get() == r.get(); }
 101
 102 template<class T>
 103 bool operator==(const RefCountingPtr<T> &l, const T *r)
 104 { return l.get() == r; }
 105
 106 template<class T>
 107 bool operator==(const T &l, const RefCountingPtr<T> &r)
 108 { return l == r.get(); }
 109
 110 template<class T>
 111 bool operator!=(const RefCountingPtr<T> &l, const RefCountingPtr<T> &r)
 112 { return l.get() != r.get(); }
 113
 114 template<class T>
 115 bool operator!=(const RefCountingPtr<T> &l, const T *r)
 116 { return l.get() != r; }
 117
 118 template<class T>
 119 bool operator!=(const T &l, const RefCountingPtr<T> &r)
 120 { return l != r.get(); }
 121
 122 #endif // __REFCNT_HH__