base/win/enum_variant.h

   1 // Copyright (c) 2011 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_ENUM_VARIANT_H_
   6 #define BASE_WIN_ENUM_VARIANT_H_
   7
   8 #include <unknwn.h>
   9
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/win/iunknown_impl.h"
  12
  13 namespace base {
  14 namespace win {
  15
  16 // A simple implementation of IEnumVARIANT.
  17 class BASE_EXPORT EnumVariant
  18   : public IEnumVARIANT,
  19     public IUnknownImpl {
  20  public:
  21   // The constructor allocates an array of size |count|. Then use
  22   // ItemAt to set the value of each item in the array to initialize it.
  23   explicit EnumVariant(unsigned long count);
  24
  25   // Returns a mutable pointer to the item at position |index|.
  26   VARIANT* ItemAt(unsigned long index);
  27
  28   // IUnknown.
  29   ULONG STDMETHODCALLTYPE AddRef() override;
  30   ULONG STDMETHODCALLTYPE Release() override;
  31   STDMETHODIMP QueryInterface(REFIID riid, void** ppv) override;
  32
  33   // IEnumVARIANT.
  34   STDMETHODIMP Next(ULONG requested_count,
  35                     VARIANT* out_elements,
  36                     ULONG* out_elements_received) override;
  37   STDMETHODIMP Skip(ULONG skip_count) override;
  38   STDMETHODIMP Reset() override;
  39   STDMETHODIMP Clone(IEnumVARIANT** out_cloned_object) override;
  40
  41  private:
  42   ~EnumVariant() override;
  43
  44   scoped_ptr<VARIANT[]> items_;
  45   unsigned long count_;
  46   unsigned long current_index_;
  47 };
  48
  49 }  // namespace win
  50 }  // namespace base
  51
  52 #endif  // BASE_WIN_ENUM_VARIANT_H_