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Diffstat (limited to 'NorthstarDedicatedTest/include/protobuf/explicitly_constructed.h')
-rw-r--r-- | NorthstarDedicatedTest/include/protobuf/explicitly_constructed.h | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/NorthstarDedicatedTest/include/protobuf/explicitly_constructed.h b/NorthstarDedicatedTest/include/protobuf/explicitly_constructed.h new file mode 100644 index 00000000..2e691256 --- /dev/null +++ b/NorthstarDedicatedTest/include/protobuf/explicitly_constructed.h @@ -0,0 +1,91 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. All rights reserved. +// https://developers.google.com/protocol-buffers/ +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#ifndef GOOGLE_PROTOBUF_EXPLICITLY_CONSTRUCTED_H__ +#define GOOGLE_PROTOBUF_EXPLICITLY_CONSTRUCTED_H__ + +#include <stdint.h> + +#include <utility> + +#include <stubs/logging.h> +#include <stubs/common.h> + +// clang-format off +#include <port_def.inc> +// clang-format on + +namespace google { +namespace protobuf { +namespace internal { + +// Wraps a variable whose constructor and destructor are explicitly +// called. It is particularly useful for a global variable, without its +// constructor and destructor run on start and end of the program lifetime. +// This circumvents the initial construction order fiasco, while keeping +// the address of the empty string a compile time constant. +// +// Pay special attention to the initialization state of the object. +// 1. The object is "uninitialized" to begin with. +// 2. Call Construct() or DefaultConstruct() only if the object is +// uninitialized. After the call, the object becomes "initialized". +// 3. Call get() and get_mutable() only if the object is initialized. +// 4. Call Destruct() only if the object is initialized. +// After the call, the object becomes uninitialized. +template <typename T> +class ExplicitlyConstructed { + public: + void DefaultConstruct() { new (&union_) T(); } + + template <typename... Args> + void Construct(Args&&... args) { + new (&union_) T(std::forward<Args>(args)...); + } + + void Destruct() { get_mutable()->~T(); } + + constexpr const T& get() const { return reinterpret_cast<const T&>(union_); } + T* get_mutable() { return reinterpret_cast<T*>(&union_); } + + private: + union AlignedUnion { + alignas(T) char space[sizeof(T)]; + int64_t align_to_int64; + void* align_to_ptr; + } union_; +}; + +} // namespace internal +} // namespace protobuf +} // namespace google + +#include <port_undef.inc> + +#endif // GOOGLE_PROTOBUF_EXPLICITLY_CONSTRUCTED_H__ |