74 lines
1.8 KiB
C++
74 lines
1.8 KiB
C++
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//
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// Boost.Pointer Container
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//
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// Copyright Thorsten Ottosen 2003-2005. Use, modification and
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// distribution is subject to the Boost Software License, Version
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// 1.0. (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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// For more information, see http://www.boost.org/libs/ptr_container/
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//
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#ifndef BOOST_INDIRECT_CONTAINER_NULLABLE_HPP
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#define BOOST_INDIRECT_CONTAINER_NULLABLE_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif
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#include <boost/type_traits/detail/yes_no_type.hpp>
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#include <boost/mpl/eval_if.hpp>
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#include <boost/mpl/identity.hpp>
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#include <boost/config.hpp>
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namespace boost
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{
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template< class T >
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struct nullable
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{
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typedef T type;
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};
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namespace ptr_container_detail
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{
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template< class T >
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type_traits::yes_type is_nullable( const nullable<T>* );
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type_traits::no_type is_nullable( ... );
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}
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template< class T >
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struct is_nullable
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{
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private:
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BOOST_STATIC_CONSTANT( T*, var );
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public:
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#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
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#pragma warning(push)
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#pragma warning(disable:6334)
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#endif
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BOOST_STATIC_CONSTANT(bool, value = sizeof( ptr_container_detail::is_nullable( var ) )
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== sizeof( type_traits::yes_type ) );
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#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
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#pragma warning(pop)
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#endif
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};
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template< class T >
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struct remove_nullable
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{
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typedef BOOST_DEDUCED_TYPENAME mpl::eval_if< is_nullable<T>,
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T,
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mpl::identity<T> >::type
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type;
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};
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}
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#endif
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