base/win/enum_variant.cc

   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 #include "base/win/enum_variant.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/logging.h"
  10
  11 namespace base {
  12 namespace win {
  13
  14 EnumVariant::EnumVariant(unsigned long count)
  15     : items_(new VARIANT[count]),
  16       count_(count),
  17       current_index_(0) {
  18 }
  19
  20 EnumVariant::~EnumVariant() {
  21 }
  22
  23 VARIANT* EnumVariant::ItemAt(unsigned long index) {
  24   DCHECK(index < count_);
  25   return &items_[index];
  26 }
  27
  28 ULONG STDMETHODCALLTYPE EnumVariant::AddRef() {
  29   return IUnknownImpl::AddRef();
  30 }
  31
  32 ULONG STDMETHODCALLTYPE EnumVariant::Release() {
  33   return IUnknownImpl::Release();
  34 }
  35
  36 STDMETHODIMP EnumVariant::QueryInterface(REFIID riid, void** ppv) {
  37   if (riid == IID_IEnumVARIANT) {
  38     *ppv = static_cast<IEnumVARIANT*>(this);
  39     AddRef();
  40     return S_OK;
  41   }
  42
  43   return IUnknownImpl::QueryInterface(riid, ppv);
  44 }
  45
  46 STDMETHODIMP EnumVariant::Next(ULONG requested_count,
  47                                VARIANT* out_elements,
  48                                ULONG* out_elements_received) {
  49   unsigned long count = std::min(requested_count, count_ - current_index_);
  50   for (unsigned long i = 0; i < count; ++i)
  51     out_elements[i] = items_[current_index_ + i];
  52   current_index_ += count;
  53   *out_elements_received = count;
  54
  55   return (count == requested_count ? S_OK : S_FALSE);
  56 }
  57
  58 STDMETHODIMP EnumVariant::Skip(ULONG skip_count) {
  59   unsigned long count = skip_count;
  60   if (current_index_ + count > count_)
  61     count = count_ - current_index_;
  62
  63   current_index_ += count;
  64   return (count == skip_count ? S_OK : S_FALSE);
  65 }
  66
  67 STDMETHODIMP EnumVariant::Reset() {
  68   current_index_ = 0;
  69   return S_OK;
  70 }
  71
  72 STDMETHODIMP EnumVariant::Clone(IEnumVARIANT** out_cloned_object) {
  73   EnumVariant* other = new EnumVariant(count_);
  74   if (count_ > 0)
  75     memcpy(other->ItemAt(0), &items_[0], count_ * sizeof(VARIANT));
  76   other->Skip(current_index_);
  77   other->AddRef();
  78   *out_cloned_object = other;
  79   return S_OK;
  80 }
  81
  82 }  // namespace win
  83 }  // namespace base