mirror of https://github.com/facebook/rocksdb.git
67 lines
2.4 KiB
C++
67 lines
2.4 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once
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#include <initializer_list>
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#include <memory>
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#include <type_traits>
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#include "rocksdb/rocksdb_namespace.h"
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namespace ROCKSDB_NAMESPACE {
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// The helper function to assert the move from dynamic_cast<> to
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// static_cast<> is correct. This function is to deal with legacy code.
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// It is not recommended to add new code to issue class casting. The preferred
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// solution is to implement the functionality without a need of casting.
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template <class DestClass, class SrcClass>
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inline DestClass* static_cast_with_check(SrcClass* x) {
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DestClass* ret = static_cast<DestClass*>(x);
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#ifdef ROCKSDB_USE_RTTI
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assert(ret == dynamic_cast<DestClass*>(x));
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#endif
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return ret;
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}
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template <class DestClass, class SrcClass>
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inline std::shared_ptr<DestClass> static_cast_with_check(
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std::shared_ptr<SrcClass>&& x) {
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#if defined(ROCKSDB_USE_RTTI) && !defined(NDEBUG)
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auto orig_raw = x.get();
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#endif
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auto ret = std::static_pointer_cast<DestClass>(std::move(x));
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#if defined(ROCKSDB_USE_RTTI) && !defined(NDEBUG)
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assert(ret.get() == dynamic_cast<DestClass*>(orig_raw));
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#endif
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return ret;
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}
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// A wrapper around static_cast for lossless conversion between integral
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// types, including enum types. For example, this can be used for converting
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// between signed/unsigned or enum type and underlying type without fear of
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// stripping away data, now or in the future.
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template <typename To, typename From>
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inline To lossless_cast(From x) {
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using FromValue = typename std::remove_reference<From>::type;
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static_assert(
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std::is_integral<FromValue>::value || std::is_enum<FromValue>::value,
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"Only works on integral types");
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static_assert(std::is_integral<To>::value || std::is_enum<To>::value,
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"Only works on integral types");
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static_assert(sizeof(To) >= sizeof(FromValue), "Must be lossless");
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return static_cast<To>(x);
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}
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// For disambiguating a potentially heterogeneous aggregate as a homogeneous
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// initializer list. E.g. might be able to write List({x, y}) in some cases
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// instead of std::vector<const Widget&>({x, y}).
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template <typename T>
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inline const std::initializer_list<T>& List(
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const std::initializer_list<T>& list) {
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return list;
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}
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} // namespace ROCKSDB_NAMESPACE
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