82 lines
3.0 KiB
C++
82 lines
3.0 KiB
C++
// Protocol Buffers - Google's data interchange format
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// Copyright 2008 Google Inc. All rights reserved.
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// https://developers.google.com/protocol-buffers/
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#ifndef GOOGLE_PROTOBUF_RAW_PTR_H__
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#define GOOGLE_PROTOBUF_RAW_PTR_H__
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#include <algorithm>
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#include "absl/base/optimization.h"
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// Must be included last.
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#include "google/protobuf/port_def.inc"
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namespace google {
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namespace protobuf {
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namespace internal {
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PROTOBUF_EXPORT ABSL_CACHELINE_ALIGNED extern const char
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kZeroBuffer[std::max(ABSL_CACHELINE_SIZE, 64)];
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// This class is trivially copyable/trivially destructible and constexpr
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// constructible. The class allows for storing a raw pointer to a non-trivial
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// object in a constexpr context.
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template <typename T>
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class RawPtr {
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public:
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constexpr RawPtr() : RawPtr(kZeroBuffer) {
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static_assert(sizeof(T) <= sizeof(kZeroBuffer), "");
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static_assert(alignof(T) <= ABSL_CACHELINE_SIZE, "");
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}
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explicit constexpr RawPtr(const void* p) : p_(const_cast<void*>(p)) {}
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bool IsDefault() const { return p_ == kZeroBuffer; }
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void Set(const void* p) { p_ = const_cast<void*>(p); }
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T* Get() const { return reinterpret_cast<T*>(p_); }
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T* operator->() const { return Get(); }
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T& operator*() const { return *Get(); }
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private:
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void* p_;
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};
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constexpr void* DefaultRawPtr() {
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return const_cast<void*>(static_cast<const void*>(kZeroBuffer));
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}
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} // namespace internal
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} // namespace protobuf
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} // namespace google
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#include "google/protobuf/port_undef.inc"
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#endif // GOOGLE_PROTOBUF_RAW_PTR_H__
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