ceph/src/boost/boost/log/detail/allocator_traits.hpp

   1 /*
   2  *             Copyright Andrey Semashev 2018.
   3  * Distributed under the Boost Software License, Version 1.0.
   4  *    (See accompanying file LICENSE_1_0.txt or copy at
   5  *          http://www.boost.org/LICENSE_1_0.txt)
   6  */
   7 /*!
   8  * \file   allocator_traits.hpp
   9  * \author Andrey Semashev
  10  * \date   03.01.2018
  11  *
  12  * \brief  This header is the Boost.Log library implementation, see the library documentation
  13  *         at http://www.boost.org/doc/libs/release/libs/log/doc/html/index.html.
  14  */
  15
  16 #ifndef BOOST_LOG_ALLOCATOR_TRAITS_HPP_INCLUDED_
  17 #define BOOST_LOG_ALLOCATOR_TRAITS_HPP_INCLUDED_
  18
  19 #include <memory>
  20 #include <boost/log/detail/config.hpp>
  21 #if defined(BOOST_NO_CXX11_ALLOCATOR)
  22 #include <boost/container/allocator_traits.hpp>
  23 #endif
  24 #include <boost/log/detail/header.hpp>
  25
  26 #ifdef BOOST_HAS_PRAGMA_ONCE
  27 #pragma once
  28 #endif
  29
  30 namespace boost {
  31
  32 BOOST_LOG_OPEN_NAMESPACE
  33
  34 namespace aux {
  35
  36 // A portable name for allocator traits
  37 #if !defined(BOOST_NO_CXX11_ALLOCATOR)
  38 using std::allocator_traits;
  39 #else
  40 using boost::container::allocator_traits;
  41 #endif
  42
  43 /*!
  44  * \brief A standalone trait to rebind an allocator to another type.
  45  *
  46  * The important difference from <tt>std::allocator_traits&lt;Alloc&gt;::rebind_alloc&lt;U&gt;</tt> is that this
  47  * trait does not require template aliases and thus is compatible with C++03. There is
  48  * <tt>boost::container::allocator_traits&lt;Alloc&gt;::portable_rebind_alloc&lt;U&gt;</tt>, but it is not present in <tt>std::allocator_traits</tt>.
  49  * It will also attempt to instantiate the allocator type to test if it provides the nested <tt>rebind</tt> template. We don't want
  50  * that to happen because it prohibits using <tt>std::allocator&lt;void&gt;</tt> in C++17 and later, which deprecated
  51  * this allocator specialization. This standalone trait does not use the nested <tt>rebind</tt> template in this case.
  52  */
  53 template< typename Allocator, typename U >
  54 struct rebind_alloc
  55 {
  56 #if !defined(BOOST_NO_CXX11_ALLOCATOR)
  57     typedef typename std::allocator_traits< Allocator >::BOOST_NESTED_TEMPLATE rebind_alloc< U > type;
  58 #else
  59     typedef typename boost::container::allocator_traits< Allocator >::BOOST_NESTED_TEMPLATE portable_rebind_alloc< U >::type type;
  60 #endif
  61 };
  62
  63 template< typename U >
  64 struct rebind_alloc< std::allocator< void >, U >
  65 {
  66     typedef std::allocator< U > type;
  67 };
  68
  69 } // namespace aux
  70
  71 BOOST_LOG_CLOSE_NAMESPACE // namespace log
  72
  73 } // namespace boost
  74
  75 #include <boost/log/detail/footer.hpp>
  76
  77 #endif // BOOST_LOG_ALLOCATOR_TRAITS_HPP_INCLUDED_