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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/win/enum_variant.h"
#include <wrl/client.h>
#include <algorithm>
#include "base/check_op.h"
namespace base {
namespace win {
EnumVariant::EnumVariant(ULONG count) : current_index_(0) {
for (ULONG i = 0; i < count; ++i)
items_.emplace_back(ScopedVariant::kEmptyVariant);
}
EnumVariant::~EnumVariant() = default;
VARIANT* EnumVariant::ItemAt(ULONG index) {
DCHECK_LT(index, items_.size());
// This is a hack to return a mutable pointer to the ScopedVariant, even
// though the original intent of the AsInput method was to allow only readonly
// access to the wrapped variant.
return items_[index].AsInput();
}
HRESULT EnumVariant::Next(ULONG requested_count,
VARIANT* out_elements,
ULONG* out_elements_received) {
if (!out_elements)
return E_INVALIDARG;
DCHECK_LE(current_index_, items_.size());
ULONG available_count = ULONG{items_.size()} - current_index_;
ULONG count = std::min(requested_count, available_count);
for (ULONG i = 0; i < count; ++i)
out_elements[i] = items_[current_index_ + i].Copy();
current_index_ += count;
// The caller can choose not to get the number of received elements by setting
// |out_elements_received| to nullptr.
if (out_elements_received)
*out_elements_received = count;
return (count == requested_count ? S_OK : S_FALSE);
}
HRESULT EnumVariant::Skip(ULONG skip_count) {
ULONG count = skip_count;
if (current_index_ + count > ULONG{items_.size()})
count = ULONG{items_.size()} - current_index_;
current_index_ += count;
return (count == skip_count ? S_OK : S_FALSE);
}
HRESULT EnumVariant::Reset() {
current_index_ = 0;
return S_OK;
}
HRESULT EnumVariant::Clone(IEnumVARIANT** out_cloned_object) {
if (!out_cloned_object)
return E_INVALIDARG;
size_t count = items_.size();
Microsoft::WRL::ComPtr<EnumVariant> other =
Microsoft::WRL::Make<EnumVariant>(ULONG{count});
for (size_t i = 0; i < count; ++i)
other->items_[i] = static_cast<const VARIANT&>(items_[i]);
other->Skip(current_index_);
return other.CopyTo(IID_PPV_ARGS(out_cloned_object));
}
} // namespace win
} // namespace base
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