michael@0: 
michael@0: /*
michael@0:  * Copyright 2011 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #ifndef SkTScopedComPtr_DEFINED
michael@0: #define SkTScopedComPtr_DEFINED
michael@0: 
michael@0: #include "SkTypes.h"
michael@0: #include "SkTemplates.h"
michael@0: 
michael@0: template<typename T>
michael@0: class SkBlockComRef : public T {
michael@0: private:
michael@0:     virtual ULONG STDMETHODCALLTYPE AddRef(void) = 0;
michael@0:     virtual ULONG STDMETHODCALLTYPE Release(void) = 0;
michael@0: };
michael@0: 
michael@0: template<typename T> T* SkRefComPtr(T* ptr) {
michael@0:     ptr->AddRef();
michael@0:     return ptr;
michael@0: }
michael@0: 
michael@0: template<typename T> T* SkSafeRefComPtr(T* ptr) {
michael@0:     if (ptr) {
michael@0:         ptr->AddRef();
michael@0:     }
michael@0:     return ptr;
michael@0: }
michael@0: 
michael@0: template<typename T>
michael@0: class SkTScopedComPtr : SkNoncopyable {
michael@0: private:
michael@0:     T *fPtr;
michael@0: 
michael@0: public:
michael@0:     explicit SkTScopedComPtr(T *ptr = NULL) : fPtr(ptr) { }
michael@0:     ~SkTScopedComPtr() {
michael@0:         this->reset();
michael@0:     }
michael@0:     T &operator*() const { SkASSERT(fPtr != NULL); return *fPtr; }
michael@0:     SkBlockComRef<T> *operator->() const {
michael@0:         return static_cast<SkBlockComRef<T>*>(fPtr);
michael@0:     }
michael@0:     /**
michael@0:      * Returns the address of the underlying pointer.
michael@0:      * This is dangerous -- it breaks encapsulation and the reference escapes.
michael@0:      * Must only be used on instances currently pointing to NULL,
michael@0:      * and only to initialize the instance.
michael@0:      */
michael@0:     T **operator&() { SkASSERT(fPtr == NULL); return &fPtr; }
michael@0:     T *get() const { return fPtr; }
michael@0:     void reset() {
michael@0:         if (NULL != this->fPtr) {
michael@0:             this->fPtr->Release();
michael@0:             this->fPtr = NULL;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     void swap(SkTScopedComPtr<T>& that) {
michael@0:         T* temp = this->fPtr;
michael@0:         this->fPtr = that.fPtr;
michael@0:         that.fPtr = temp;
michael@0:     }
michael@0: 
michael@0:     T* release() {
michael@0:         T* temp = this->fPtr;
michael@0:         this->fPtr = NULL;
michael@0:         return temp;
michael@0:     }
michael@0: };
michael@0: 
michael@0: #endif