life.hpp

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/*
 * Copyright 2016-2019, Intel Corporation
 *
 * 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 the copyright holder 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 LIBPMEMOBJ_CPP_DESTROYER_HPP
#define LIBPMEMOBJ_CPP_DESTROYER_HPP

#include <cstddef>
#include <type_traits>
#include <utility>

#include <libpmemobj++/detail/array_traits.hpp>
#include <libpmemobj++/detail/integer_sequence.hpp>

namespace pmem
{

namespace detail
{

/*
 * Template for checking if T is not an array.
 */
template <typename T>
struct if_not_array {
    typedef T type;
};

/*
 * Template for checking if T is not an array.
 */
template <typename T>
struct if_not_array<T[]>;

/*
 * Template for checking if T is not an array.
 */
template <typename T, size_t N>
struct if_not_array<T[N]>;

/*
 * Template for checking if T is an array.
 */
template <typename T>
struct if_size_array;

/*
 * Template for checking if T is an array.
 */
template <typename T>
struct if_size_array<T[]>;

/*
 * Template for checking if T is an array.
 */
template <typename T, size_t N>
struct if_size_array<T[N]> {
    typedef T type[N];
};

/*
 * Calls object's constructor.
 *
 * Supports aggregate initialization since C++17
 */
template <typename T, typename... Args>
void
create(typename if_not_array<T>::type *ptr, Args &&... args)
{
#if __cpp_lib_is_aggregate
    if constexpr (std::is_aggregate_v<T>)
        new (static_cast<void *>(ptr)) T{std::forward<Args>(args)...};
    else
        new (static_cast<void *>(ptr)) T(std::forward<Args>(args)...);
#else
    new (static_cast<void *>(ptr)) T(std::forward<Args>(args)...);
#endif
}

/*
 * Recursively calls array's elements' constructors.
 */
template <typename T, typename... Args>
void
create(typename if_size_array<T>::type *ptr, Args &&... args)
{
    typedef typename detail::pp_array_type<T>::type I;
    enum { N = pp_array_elems<T>::elems };

    for (std::size_t i = 0; i < N; ++i)
        create<I>(&(*ptr)[i], std::forward<Args>(args)...);
}

/*
 * Calls the objects constructor.
 *
 * Unpacks the tuple to get constructor's parameters.
 */
template <typename T, size_t... Indices, typename Tuple>
void
create_from_tuple(void *ptr, index_sequence<Indices...>, Tuple tuple)
{
    new (ptr) T(std::get<Indices>(std::move(tuple))...);
}

/*
 * C-style function which calls T constructor with arguments packed in a tuple.
 *
 * The arg is a tuple containing constructor parameters.
 */
template <typename T, typename Tuple, typename... Args>
int
c_style_construct(void *ptr, void *arg)
{
    auto *arg_pack = static_cast<Tuple *>(arg);

    typedef typename make_index_sequence<Args...>::type index;
    try {
        create_from_tuple<T>(ptr, index(), std::move(*arg_pack));
    } catch (...) {
        return -1;
    }

    return 0;
}

/*
 * Calls object's destructor.
 */
template <typename T,
      typename = typename std::enable_if<!std::is_pod<T>::value>::type>
void
destroy(typename if_not_array<T>::type &arg)
{
    arg.~T();
}

/*
 * Don't call destructors for POD types.
 */
template <typename T, typename dummy = void,
      typename = typename std::enable_if<std::is_pod<T>::value>::type>
void
destroy(typename if_not_array<T>::type &)
{
}

/*
 * Recursively calls array's elements' destructors.
 */
template <typename T>
void
destroy(typename if_size_array<T>::type &arg)
{
    typedef typename detail::pp_array_type<T>::type I;
    enum { N = pp_array_elems<T>::elems };

    for (std::size_t i = 0; i < N; ++i)
        destroy<I>(arg[N - 1 - i]);
}

} /* namespace detail */

} /* namespace pmem */

#endif /* LIBPMEMOBJ_CPP_DESTROYER_HPP */