17a74ddd3d
PR-URL: https://github.com/nodejs/node/pull/49639 Reviewed-By: Jiawen Geng <technicalcute@gmail.com> Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com> Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
40 lines
1.2 KiB
C++
40 lines
1.2 KiB
C++
// Copyright 2021 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef INCLUDE_CPPGC_SENTINEL_POINTER_H_
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#define INCLUDE_CPPGC_SENTINEL_POINTER_H_
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#include <cstdint>
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#include "cppgc/internal/api-constants.h"
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namespace cppgc {
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namespace internal {
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// Special tag type used to denote some sentinel member. The semantics of the
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// sentinel is defined by the embedder.
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struct SentinelPointer {
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#if defined(CPPGC_POINTER_COMPRESSION)
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static constexpr intptr_t kSentinelValue =
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1 << api_constants::kPointerCompressionShift;
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#else // !defined(CPPGC_POINTER_COMPRESSION)
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static constexpr intptr_t kSentinelValue = 0b10;
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#endif // !defined(CPPGC_POINTER_COMPRESSION)
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template <typename T>
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operator T*() const {
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return reinterpret_cast<T*>(kSentinelValue);
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}
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// Hidden friends.
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friend bool operator==(SentinelPointer, SentinelPointer) { return true; }
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friend bool operator!=(SentinelPointer, SentinelPointer) { return false; }
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};
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} // namespace internal
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constexpr internal::SentinelPointer kSentinelPointer;
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} // namespace cppgc
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#endif // INCLUDE_CPPGC_SENTINEL_POINTER_H_
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