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cpbroke.h
1 /*
2 * Copyright (C) 2012 by Glenn Hickey (hickey@soe.ucsc.edu)
3 *
4 * Released under the MIT license, see LICENSE.txt
5 */
6
7
22 /*
23 * counted_ptr - simple reference counted pointer.
24 *
25 * The is a non-intrusive implementation that allocates an additional
26 * int and pointer for every counted object.
27 */
28
29 #ifndef COUNTED_PTR_H
30 #define COUNTED_PTR_H
31
32 namespace hal {
33
34 template<typename X>
35 struct ptr_counter {
36 ptr_counter(X* p = 0, unsigned c = 1) : ptr(p), count(c) {}
37 X* ptr;
38 unsigned count;
39 };
40
41 template <class X>
42 class counted_ptr
43 {
44 public:
45 template <typename XX> friend class counted_ptr;
46 typedef ptr_counter<X> counter;
47
48 explicit counted_ptr(X* p = 0) // allocate a new counter
49 : itsCounter(0) {
50 if (p) itsCounter = new counter(p);
51 }
52
53 ~counted_ptr() {
54 release();
55 }
56
57 template <class Y>
58 counted_ptr(const counted_ptr<Y>& r) {
59 acquire<Y>(r.itsCounter);
60 }
61
62 template <class Y>
63 counted_ptr& operator=(const counted_ptr<Y>& r) {
64 if (const_cast<const counted_ptr<X>*>(this) !=
65 reinterpret_cast<const counted_ptr<X>*>(
66 const_cast<const counted_ptr<Y>*>(&r)))
67 {
68 release();
69 acquire<Y>(r.itsCounter);
70 }
71 return *this;
72 }
73
74 X& operator*() const {return *itsCounter->ptr;}
75 X* operator->() const {return itsCounter->ptr;}
76 X* get() const {return itsCounter ? itsCounter->ptr : 0;}
77 bool unique() const {
78 return (itsCounter ? itsCounter->count == 1 : true);
79 }
80
81 private:
82
83 counter* itsCounter;
84
85 template <typename Y>
86 void acquire(ptr_counter<Y>* c) {
87 if (c) {
88 (void)static_cast<X*>(c->ptr);
89 itsCounter = reinterpret_cast<counter*>(c);
90 ++c->count;
91 }
92 else {
93 itsCounter = NULL;
94 }
95 }
96
97 void release() {
98 if (itsCounter) {
99 if (--itsCounter->count == 0) {
100 delete itsCounter->ptr;
101 delete itsCounter;
102 }
103 itsCounter = 0;
104 }
105 }
106 };
107
108
109 }
110 #endif // COUNTED_PTR_H