1 // Copyright (c) 2013 The Chromium Authors. All rights reserved. 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/basictypes.h" 11 #include "base/logging.h" 12 13 namespace base { 14 namespace win { 15 16 // A PROPVARIANT that is automatically initialized and cleared upon respective 17 // construction and destruction of this class. 18 class ScopedPropVariant { 19 public: ScopedPropVariant()20 ScopedPropVariant() { 21 PropVariantInit(&pv_); 22 } 23 ~ScopedPropVariant()24 ~ScopedPropVariant() { 25 Reset(); 26 } 27 28 // Returns a pointer to the underlying PROPVARIANT for use as an out param in 29 // a function call. Receive()30 PROPVARIANT* Receive() { 31 DCHECK_EQ(pv_.vt, VT_EMPTY); 32 return &pv_; 33 } 34 35 // Clears the instance to prepare it for re-use (e.g., via Receive). Reset()36 void Reset() { 37 if (pv_.vt != VT_EMPTY) { 38 HRESULT result = PropVariantClear(&pv_); 39 DCHECK_EQ(result, S_OK); 40 } 41 } 42 get()43 const PROPVARIANT& get() const { return pv_; } 44 45 const PROPVARIANT* operator&() const { return &pv_; } 46 47 private: 48 PROPVARIANT pv_; 49 50 // Comparison operators for ScopedPropVariant are not supported at this point. 51 bool operator==(const ScopedPropVariant&) const; 52 bool operator!=(const ScopedPropVariant&) const; 53 DISALLOW_COPY_AND_ASSIGN(ScopedPropVariant); 54 }; 55 56 } // namespace win 57 } // namespace base 58 59 #endif // BASE_WIN_SCOPED_PROPVARIANT_H_ 60