OpenShot Audio Library | OpenShotAudio  0.3.0
juce_WeakReference.h
1 /*
2  ==============================================================================
3 
4  This file is part of the JUCE library.
5  Copyright (c) 2017 - ROLI Ltd.
6 
7  JUCE is an open source library subject to commercial or open-source
8  licensing.
9 
10  The code included in this file is provided under the terms of the ISC license
11  http://www.isc.org/downloads/software-support-policy/isc-license. Permission
12  To use, copy, modify, and/or distribute this software for any purpose with or
13  without fee is hereby granted provided that the above copyright notice and
14  this permission notice appear in all copies.
15 
16  JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
17  EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
18  DISCLAIMED.
19 
20  ==============================================================================
21 */
22 
23 namespace juce
24 {
25 
26 //==============================================================================
76 template <class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
78 {
79 public:
81  inline WeakReference() = default;
82 
84  WeakReference (ObjectType* object) : holder (getRef (object)) {}
85 
87  WeakReference (const WeakReference& other) noexcept : holder (other.holder) {}
88 
90  WeakReference (WeakReference&& other) noexcept : holder (std::move (other.holder)) {}
91 
93  WeakReference& operator= (const WeakReference& other) { holder = other.holder; return *this; }
94 
96  WeakReference& operator= (ObjectType* newObject) { holder = getRef (newObject); return *this; }
97 
99  WeakReference& operator= (WeakReference&& other) noexcept { holder = std::move (other.holder); return *this; }
100 
102  ObjectType* get() const noexcept { return holder != nullptr ? holder->get() : nullptr; }
103 
105  operator ObjectType*() const noexcept { return get(); }
106 
108  ObjectType* operator->() const noexcept { return get(); }
109 
117  bool wasObjectDeleted() const noexcept { return holder != nullptr && holder->get() == nullptr; }
118 
119  bool operator== (ObjectType* object) const noexcept { return get() == object; }
120  bool operator!= (ObjectType* object) const noexcept { return get() != object; }
121 
122  //==============================================================================
127  class SharedPointer : public ReferenceCountingType
128  {
129  public:
130  explicit SharedPointer (ObjectType* obj) noexcept : owner (obj) {}
131 
132  inline ObjectType* get() const noexcept { return owner; }
133  void clearPointer() noexcept { owner = nullptr; }
134 
135  private:
136  ObjectType* owner;
137 
138  JUCE_DECLARE_NON_COPYABLE (SharedPointer)
139  };
140 
142 
143  //==============================================================================
149  class Master
150  {
151  public:
152  Master() = default;
153 
154  ~Master() noexcept
155  {
156  // You must remember to call clear() in your source object's destructor! See the notes
157  // for the WeakReference class for an example of how to do this.
158  jassert (sharedPointer == nullptr || sharedPointer->get() == nullptr);
159  }
160 
164  SharedRef getSharedPointer (ObjectType* object)
165  {
166  if (sharedPointer == nullptr)
167  {
168  sharedPointer = *new SharedPointer (object);
169  }
170  else
171  {
172  // You're trying to create a weak reference to an object that has already been deleted!!
173  jassert (sharedPointer->get() != nullptr);
174  }
175 
176  return sharedPointer;
177  }
178 
183  void clear() noexcept
184  {
185  if (sharedPointer != nullptr)
186  sharedPointer->clearPointer();
187  }
188 
190  int getNumActiveWeakReferences() const noexcept
191  {
192  return sharedPointer == nullptr ? 0 : (sharedPointer->getReferenceCount() - 1);
193  }
194 
195  private:
196  SharedRef sharedPointer;
197 
198  JUCE_DECLARE_NON_COPYABLE (Master)
199  };
200 
201 private:
202  SharedRef holder;
203 
204  static inline SharedRef getRef (ObjectType* o)
205  {
206  if (o != nullptr)
207  return o->masterReference.getSharedPointer (o);
208 
209  return {};
210  }
211 };
212 
213 
214 //==============================================================================
234 #define JUCE_DECLARE_WEAK_REFERENCEABLE(Class) \
235  struct WeakRefMaster : public juce::WeakReference<Class>::Master { ~WeakRefMaster() { this->clear(); } }; \
236  WeakRefMaster masterReference; \
237  friend class juce::WeakReference<Class>; \
238 
239 
240 } // namespace juce
bool wasObjectDeleted() const noexcept
SharedRef getSharedPointer(ObjectType *object)
int getNumActiveWeakReferences() const noexcept
ObjectType * operator->() const noexcept
ReferencedType * get() const noexcept
WeakReference(ObjectType *object)
WeakReference()=default
WeakReference(WeakReference &&other) noexcept
WeakReference(const WeakReference &other) noexcept
WeakReference & operator=(const WeakReference &other)