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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_BASE_METADATA_METADATA_UTILS_H_
#define UI_BASE_METADATA_METADATA_UTILS_H_
#include <type_traits>
#include "build/build_config.h"
#include "build/buildflag.h"
#include "ui/base/metadata/metadata_types.h"
namespace ui::metadata {
template <typename T, typename = void>
static constexpr bool kHasClassMetadata = false;
template <typename T>
static constexpr bool kHasClassMetadata<
T,
std::void_t<
typename std::remove_cvref_t<std::remove_pointer_t<T>>::kMetadataTag>> =
std::is_same_v<
typename std::remove_cvref_t<std::remove_pointer_t<T>>::kMetadataTag,
typename std::remove_cvref_t<std::remove_pointer_t<T>>>;
#define CHECK_CLASS_HAS_METADATA(class_type) \
static_assert(ui::metadata::kHasClassMetadata<class_type>, \
"The class_type param doesn't implement metadata. Make sure " \
"class publicly calls METADATA_HEADER in the declaration.");
template <typename V, typename B>
bool IsClass(const B* instance) {
if (!instance) {
return false;
}
CHECK_CLASS_HAS_METADATA(V)
static_assert(std::is_base_of_v<B, V>,
"Only classes derived from template param B allowed");
const ClassMetaData* child = instance->GetClassMetaData();
for (const ClassMetaData* parent = V::MetaData(); child && child != parent;
child = child->parent_class_meta_data())
;
return !!child;
}
template <typename V, typename B>
V* AsClass(B* instance) {
return IsClass<V, B>(instance) ? static_cast<V*>(instance) : nullptr;
}
template <typename V, typename B>
const V* AsClass(const B* instance) {
return IsClass<V, B>(instance) ? static_cast<const V*>(instance) : nullptr;
}
} // namespace ui::metadata
#endif // UI_BASE_METADATA_METADATA_UTILS_H_
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