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// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_HEAP_TRAITS_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_HEAP_TRAITS_H_
#include <type_traits>
#include "third_party/blink/renderer/platform/heap/collection_support/heap_vector.h"
#include "third_party/blink/renderer/platform/heap/member.h"
#include "third_party/blink/renderer/platform/wtf/type_traits.h"
namespace blink {
namespace internal {
template <typename T>
inline constexpr bool IsHeapVector = false;
template <typename T>
inline constexpr bool IsHeapVector<HeapVector<T>> = true;
} // namespace internal
// Given a type T, returns a type that is either Member<T> or just T depending
// on whether T is a garbage-collected type.
template <typename T>
using AddMemberIfNeeded =
std::conditional_t<WTF::IsGarbageCollectedType<T>::value &&
!internal::IsHeapVector<T>,
Member<T>,
T>;
// Given a type T, returns a type that is either HeapVector<T>,
// HeapVector<Member<T>> or Vector<T> depending on T.
template <typename T>
using VectorOf = std::conditional_t<WTF::IsTraceable<T>::value,
HeapVector<AddMemberIfNeeded<T>>,
Vector<T>>;
// Given types T and U, returns a type that is one of the following:
// - HeapVector<std::pair<V, X>>
// (where V is either T or Member<T> and X is either U or Member<U>)
// - Vector<std::pair<T, U>>
template <typename T, typename U>
using VectorOfPairs = std::conditional_t<
WTF::IsTraceable<T>::value || WTF::IsTraceable<U>::value,
HeapVector<std::pair<AddMemberIfNeeded<T>, AddMemberIfNeeded<U>>>,
Vector<std::pair<T, U>>>;
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_HEAP_TRAITS_H_
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