88 lines
2.7 KiB
C++
88 lines
2.7 KiB
C++
/*
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* Copyright Andrey Semashev 2018.
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*/
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/*!
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* \file allocator_traits.hpp
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* \author Andrey Semashev
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* \date 03.01.2018
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*
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* \brief This header is the Boost.Log library implementation, see the library documentation
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* at http://www.boost.org/doc/libs/release/libs/log/doc/html/index.html.
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*/
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#ifndef BOOST_LOG_ALLOCATOR_TRAITS_HPP_INCLUDED_
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#define BOOST_LOG_ALLOCATOR_TRAITS_HPP_INCLUDED_
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#include <memory>
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#include <boost/log/detail/config.hpp>
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#if defined(BOOST_NO_CXX11_ALLOCATOR)
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#include <boost/container/allocator_traits.hpp>
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#endif
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#include <boost/log/utility/use_std_allocator.hpp>
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#include <boost/log/detail/header.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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#pragma once
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#endif
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namespace boost {
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BOOST_LOG_OPEN_NAMESPACE
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namespace aux {
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// A portable name for allocator traits
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#if !defined(BOOST_NO_CXX11_ALLOCATOR)
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using std::allocator_traits;
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#else
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using boost::container::allocator_traits;
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#endif
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/*!
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* \brief A standalone trait to rebind an allocator to another type.
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*
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* The important difference from <tt>std::allocator_traits<Alloc>::rebind_alloc<U></tt> is that this
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* trait does not require template aliases and thus is compatible with C++03. There is
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* <tt>boost::container::allocator_traits<Alloc>::portable_rebind_alloc<U></tt>, but it is not present in <tt>std::allocator_traits</tt>.
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*/
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template< typename Allocator, typename U >
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struct rebind_alloc
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{
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#if !defined(BOOST_NO_CXX11_ALLOCATOR)
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typedef typename std::allocator_traits< Allocator >::BOOST_NESTED_TEMPLATE rebind_alloc< U > type;
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#else
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typedef typename boost::container::allocator_traits< Allocator >::BOOST_NESTED_TEMPLATE portable_rebind_alloc< U >::type type;
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#endif
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};
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/*!
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* This specialization mostly exists to keep <tt>std::allocator<void></tt> working.
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* The default template will attempt to instantiate the allocator type to test if it provides the nested <tt>rebind</tt> template.
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* We don't want that to happen because it prohibits using <tt>std::allocator<void></tt> in C++17 and later, which deprecated
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* this allocator specialization. This specialization does not use the nested <tt>rebind</tt> template in this case.
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*/
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template< typename T, typename U >
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struct rebind_alloc< std::allocator< T >, U >
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{
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typedef std::allocator< U > type;
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};
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template< typename U >
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struct rebind_alloc< use_std_allocator, U >
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{
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typedef std::allocator< U > type;
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};
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} // namespace aux
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BOOST_LOG_CLOSE_NAMESPACE // namespace log
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} // namespace boost
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#include <boost/log/detail/footer.hpp>
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#endif // BOOST_LOG_ALLOCATOR_TRAITS_HPP_INCLUDED_
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