1 // Copyright 2013 The Chromium Authors 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_WIN_SCOPED_PROPVARIANT_H_ 6 #define BASE_WIN_SCOPED_PROPVARIANT_H_ 7 8 #include <propidl.h> 9 10 #include "base/check_op.h" 11 12 namespace base { 13 namespace win { 14 15 // A PROPVARIANT that is automatically initialized and cleared upon respective 16 // construction and destruction of this class. 17 class ScopedPropVariant { 18 public: ScopedPropVariant()19 ScopedPropVariant() { PropVariantInit(&pv_); } 20 21 ScopedPropVariant(const ScopedPropVariant&) = delete; 22 ScopedPropVariant& operator=(const ScopedPropVariant&) = delete; 23 ~ScopedPropVariant()24 ~ScopedPropVariant() { Reset(); } 25 26 // Returns a pointer to the underlying PROPVARIANT for use as an out param in 27 // a function call. Receive()28 PROPVARIANT* Receive() { 29 DCHECK_EQ(pv_.vt, VT_EMPTY); 30 return &pv_; 31 } 32 33 // Clears the instance to prepare it for re-use (e.g., via Receive). Reset()34 void Reset() { 35 if (pv_.vt != VT_EMPTY) { 36 HRESULT result = PropVariantClear(&pv_); 37 DCHECK_EQ(result, S_OK); 38 } 39 } 40 get()41 const PROPVARIANT& get() const { return pv_; } ptr()42 const PROPVARIANT* ptr() const { return &pv_; } 43 44 private: 45 PROPVARIANT pv_; 46 47 // Comparison operators for ScopedPropVariant are not supported at this point. 48 bool operator==(const ScopedPropVariant&) const; 49 bool operator!=(const ScopedPropVariant&) const; 50 }; 51 52 } // namespace win 53 } // namespace base 54 55 #endif // BASE_WIN_SCOPED_PROPVARIANT_H_ 56