Abseil Common Libraries (C++) (grcp 依赖)
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50 lines
1.7 KiB
50 lines
1.7 KiB
7 years ago
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// Copyright 2018 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef ABSL_BASE_INTERNAL_HIDE_PTR_H_
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#define ABSL_BASE_INTERNAL_HIDE_PTR_H_
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#include <cstdint>
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namespace absl {
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namespace base_internal {
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// Arbitrary value with high bits set. Xor'ing with it is unlikely
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// to map one valid pointer to another valid pointer.
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constexpr uintptr_t HideMask() {
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static_assert(sizeof(uintptr_t) == 4 || sizeof(uintptr_t) == 8,
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"uintptr_t must be 32 or 64 bits");
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return sizeof(uintptr_t) == 8 ? 0xF03A5F7BF03A5F7BULL : 0xF03A5F7BUL;
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}
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// Hide a pointer from the leak checker. For internal use only.
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// Differs from absl::IgnoreLeak(ptr) in that absl::IgnoreLeak(ptr) causes ptr
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// and all objects reachable from ptr to be ignored by the leak checker.
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template <class T>
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inline uintptr_t HidePtr(T* ptr) {
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return reinterpret_cast<uintptr_t>(ptr) ^ HideMask();
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}
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// Return a pointer that has been hidden from the leak checker.
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// For internal use only.
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template <class T>
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inline T* UnhidePtr(uintptr_t hidden) {
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return reinterpret_cast<T*>(hidden ^ HideMask());
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}
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} // namespace base_internal
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} // namespace absl
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#endif // ABSL_BASE_INTERNAL_HIDE_PTR_H_
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