MythTV  master
quicksp.h
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1 #ifndef QUICKSP_H_
2 #define QUICKSP_H_
3 
4 #include "mythmetaexp.h"
5 
6 struct NoLock
7 {
8  void lock() {}
9  void unlock() {}
10 };
11 
12 // TODO: implement for threads
13 // If implemented for threads move the instance pointer to simple_ref_ptr
14 // so simple access isn't synchronized.
15 struct ThreadLock
16 {
17  void lock() {}
18 
19  void unlock() {}
20 };
21 
22 // TODO: Get a real reference counted smart pointer in libmyth
23 template <typename T, class Locker = NoLock>
25 {
26  public:
27  simple_ref_ptr() : m_ref(nullptr)
28  {
29  }
30 
32  {
33  m_ref = new ref(ptr);
34  }
35 
36  simple_ref_ptr(const simple_ref_ptr &rhs) : m_ref(nullptr)
37  {
38  *this = rhs;
39  }
40 
42  {
43  unref();
44  }
45 
46  // The first two lines of this function are the clang-tidy
47  // recommended solution to make a function properly handle
48  // self-assignment. No idea why clang-tidy doesn't recognize
49  // this, unless it has something to do with templates?
50  //
51  // NOLINTNEXTLINE(bugprone-unhandled-self-assignment,cert-oop54-cpp)
53  {
54  if (this == &rhs)
55  return *this;
56  rhs.m_ref->inc();
57  unref();
58  m_ref = rhs.m_ref;
59 
60  return *this;
61  }
62 
63  T *operator->() const
64  {
65  return get();
66  }
67 
68  T &operator*() const
69  {
70  return *get();
71  }
72 
73  T *get() const
74  {
75  if (m_ref) return m_ref->get();
76 
77  return nullptr;
78  }
79 
80  void reset(T *ptr)
81  {
82  unref();
83  m_ref = new ref(ptr);
84  }
85 
86  using fake_bool = T *(simple_ref_ptr<T>::*)() const;
87 
88  operator fake_bool() const
89  {
90  return m_ref == nullptr ? nullptr : &simple_ref_ptr<T>::get;
91  }
92 
93  bool operator!() const
94  {
95  return m_ref == nullptr;
96  }
97 
98  private:
99  class ref : public Locker
100  {
101  public:
102  explicit ref(T *ptr) : m_count(1), m_type(ptr) {}
103 
105  {
106  delete m_type;
107  }
108 
109  unsigned int inc()
110  {
111  this->lock();
112  ++m_count;
113  this->unlock();
114  return m_count;
115  }
116 
117  unsigned int dec()
118  {
119  this->lock();
120  --m_count;
121  this->unlock();
122  return m_count;
123  }
124 
125  T *get()
126  {
127  return m_type;
128  }
129 
130  T *get() const
131  {
132  return m_type;
133  }
134 
135  private:
136  unsigned int m_count;
137  T *m_type;
138  };
139 
140  void unref()
141  {
142  if (m_ref && m_ref->dec() <= 0)
143  {
144  delete m_ref;
145  m_ref = nullptr;
146  }
147  }
148 
149  private:
150  ref *m_ref;
151 };
152 
153 template <typename T>
154 bool operator==(const simple_ref_ptr<T> &lhs, const simple_ref_ptr<T> &rhs)
155 {
156  return lhs.get() == rhs.get();
157 }
158 
159 template <typename T>
160 bool operator!=(const simple_ref_ptr<T> &lhs, const simple_ref_ptr<T> &rhs)
161 {
162  return lhs.get() != rhs.get();
163 }
164 
165 #endif // QUICKSP_H_
ref * m_ref
Definition: quicksp.h:150
~simple_ref_ptr()
Definition: quicksp.h:41
T * get() const
Definition: quicksp.h:130
simple_ref_ptr(T *ptr)
Definition: quicksp.h:31
bool operator!=(const simple_ref_ptr< T > &lhs, const simple_ref_ptr< T > &rhs)
Definition: quicksp.h:160
unsigned int m_count
Definition: quicksp.h:136
unsigned int inc()
Definition: quicksp.h:109
simple_ref_ptr & operator=(const simple_ref_ptr &rhs)
Definition: quicksp.h:52
meta_dir_node *(simple_ref_ptr< meta_dir_node >::*)() const fake_bool
Definition: quicksp.h:86
void unlock()
Definition: quicksp.h:19
Definition: quicksp.h:6
bool operator!() const
Definition: quicksp.h:93
T * operator->() const
Definition: quicksp.h:63
bool operator==(const simple_ref_ptr< T > &lhs, const simple_ref_ptr< T > &rhs)
Definition: quicksp.h:154
void unlock()
Definition: quicksp.h:9
void reset(T *ptr)
Definition: quicksp.h:80
void lock()
Definition: quicksp.h:17
T * get() const
Definition: quicksp.h:73
unsigned int dec()
Definition: quicksp.h:117
simple_ref_ptr(const simple_ref_ptr &rhs)
Definition: quicksp.h:36
void lock()
Definition: quicksp.h:8
T & operator*() const
Definition: quicksp.h:68
simple_ref_ptr()
Definition: quicksp.h:27
void unref()
Definition: quicksp.h:140