hide_ptr.h
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1 // Copyright 2018 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 #ifndef ABSL_BASE_INTERNAL_HIDE_PTR_H_
16 #define ABSL_BASE_INTERNAL_HIDE_PTR_H_
17 
18 #include <cstdint>
19 
20 namespace absl {
21 namespace base_internal {
22 
23 // Arbitrary value with high bits set. Xor'ing with it is unlikely
24 // to map one valid pointer to another valid pointer.
25 constexpr uintptr_t HideMask() {
26  return (uintptr_t{0xF03A5F7BU} << (sizeof(uintptr_t) - 4) * 8) | 0xF03A5F7BU;
27 }
28 
29 // Hide a pointer from the leak checker. For internal use only.
30 // Differs from absl::IgnoreLeak(ptr) in that absl::IgnoreLeak(ptr) causes ptr
31 // and all objects reachable from ptr to be ignored by the leak checker.
32 template <class T>
33 inline uintptr_t HidePtr(T* ptr) {
34  return reinterpret_cast<uintptr_t>(ptr) ^ HideMask();
35 }
36 
37 // Return a pointer that has been hidden from the leak checker.
38 // For internal use only.
39 template <class T>
40 inline T* UnhidePtr(uintptr_t hidden) {
41  return reinterpret_cast<T*>(hidden ^ HideMask());
42 }
43 
44 } // namespace base_internal
45 } // namespace absl
46 
47 #endif // ABSL_BASE_INTERNAL_HIDE_PTR_H_
T * UnhidePtr(uintptr_t hidden)
Definition: hide_ptr.h:40
Definition: algorithm.h:29
uintptr_t HidePtr(T *ptr)
Definition: hide_ptr.h:33
char * ptr
constexpr uintptr_t HideMask()
Definition: hide_ptr.h:25


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autogenerated on Wed Jun 19 2019 19:19:56