THUAI6/CAPI/cpp/grpc/include/absl/base/internal/hide_ptr.h

// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef ABSL_BASE_INTERNAL_HIDE_PTR_H_
#define ABSL_BASE_INTERNAL_HIDE_PTR_H_

#include <cstdint>

#include "absl/base/config.h"

namespace absl
{
    ABSL_NAMESPACE_BEGIN
    namespace base_internal
    {

        // Arbitrary value with high bits set. Xor'ing with it is unlikely
        // to map one valid pointer to another valid pointer.
        constexpr uintptr_t HideMask()
        {
            return (uintptr_t{0xF03A5F7BU} << (sizeof(uintptr_t) - 4) * 8) | 0xF03A5F7BU;
        }

        // Hide a pointer from the leak checker. For internal use only.
        // Differs from absl::IgnoreLeak(ptr) in that absl::IgnoreLeak(ptr) causes ptr
        // and all objects reachable from ptr to be ignored by the leak checker.
        template<class T>
        inline uintptr_t HidePtr(T* ptr)
        {
            return reinterpret_cast<uintptr_t>(ptr) ^ HideMask();
        }

        // Return a pointer that has been hidden from the leak checker.
        // For internal use only.
        template<class T>
        inline T* UnhidePtr(uintptr_t hidden)
        {
            return reinterpret_cast<T*>(hidden ^ HideMask());
        }

    }  // namespace base_internal
    ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_BASE_INTERNAL_HIDE_PTR_H_