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1 /*
2  * Copyright 2011 Google Inc.
3  *
4  * Use of this source code is governed by a BSD-style license that can be
5  * found in the LICENSE file.
6  */
7 
8 #ifndef SkTScopedComPtr_DEFINED
9 #define SkTScopedComPtr_DEFINED
10 
11 #include "src/core/SkLeanWindows.h"
12 #include "src/utils/win/SkObjBase.h"
13 
14 #ifdef SK_BUILD_FOR_WIN
15 
SkRefComPtr(T * ptr)16 template<typename T> T* SkRefComPtr(T* ptr) {
17     ptr->AddRef();
18     return ptr;
19 }
20 
SkSafeRefComPtr(T * ptr)21 template<typename T> T* SkSafeRefComPtr(T* ptr) {
22     if (ptr) {
23         ptr->AddRef();
24     }
25     return ptr;
26 }
27 
28 template<typename T>
29 class SkTScopedComPtr {
30 private:
31     T *fPtr;
32 
33 public:
SkTScopedComPtr()34     constexpr SkTScopedComPtr() : fPtr(nullptr) {}
SkTScopedComPtr(std::nullptr_t)35     constexpr SkTScopedComPtr(std::nullptr_t) : fPtr(nullptr) {}
SkTScopedComPtr(T * ptr)36     explicit SkTScopedComPtr(T *ptr) : fPtr(ptr) {}
SkTScopedComPtr(SkTScopedComPtr && that)37     SkTScopedComPtr(SkTScopedComPtr&& that) : fPtr(that.release()) {}
38     SkTScopedComPtr(const SkTScopedComPtr&) = delete;
39 
~SkTScopedComPtr()40     ~SkTScopedComPtr() { this->reset();}
41 
42     SkTScopedComPtr& operator=(SkTScopedComPtr&& that) {
43         this->reset(that.release());
44         return *this;
45     }
46     SkTScopedComPtr& operator=(const SkTScopedComPtr&) = delete;
47     SkTScopedComPtr& operator=(std::nullptr_t) { this->reset(); return *this; }
48 
49     T &operator*() const { SkASSERT(fPtr != nullptr); return *fPtr; }
50 
51     explicit operator bool() const { return fPtr != nullptr; }
52 
53     T *operator->() const { return fPtr; }
54 
55     /**
56      * Returns the address of the underlying pointer.
57      * This is dangerous -- it breaks encapsulation and the reference escapes.
58      * Must only be used on instances currently pointing to NULL,
59      * and only to initialize the instance.
60      */
61     T **operator&() { SkASSERT(fPtr == nullptr); return &fPtr; }
62 
get()63     T *get() const { return fPtr; }
64 
65     void reset(T* ptr = nullptr) {
66         if (fPtr) {
67             fPtr->Release();
68         }
69         fPtr = ptr;
70     }
71 
swap(SkTScopedComPtr<T> & that)72     void swap(SkTScopedComPtr<T>& that) {
73         T* temp = this->fPtr;
74         this->fPtr = that.fPtr;
75         that.fPtr = temp;
76     }
77 
release()78     T* release() {
79         T* temp = this->fPtr;
80         this->fPtr = nullptr;
81         return temp;
82     }
83 };
84 
85 #endif  // SK_BUILD_FOR_WIN
86 #endif  // SkTScopedComPtr_DEFINED
87