108 lines
3.1 KiB
Plaintext
108 lines
3.1 KiB
Plaintext
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#ifndef BOOST_TYPE_TRAITS_DETAIL_COMMON_TYPE_IMPL_HPP_INCLUDED
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#define BOOST_TYPE_TRAITS_DETAIL_COMMON_TYPE_IMPL_HPP_INCLUDED
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//
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// Copyright 2015 Peter Dimov
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//
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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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#include <boost/type_traits/detail/common_arithmetic_type.hpp>
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#include <boost/type_traits/detail/composite_pointer_type.hpp>
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#include <boost/type_traits/detail/composite_member_pointer_type.hpp>
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#include <boost/type_traits/type_identity.hpp>
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#include <boost/type_traits/is_class.hpp>
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#include <boost/type_traits/is_union.hpp>
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#include <boost/type_traits/is_convertible.hpp>
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#include <boost/type_traits/is_pointer.hpp>
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#include <boost/type_traits/is_member_pointer.hpp>
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#include <boost/type_traits/conditional.hpp>
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namespace boost
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{
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namespace type_traits_detail
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{
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// the arguments to common_type_impl have already been passed through decay<>
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template<class T, class U> struct common_type_impl;
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// same type
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template<class T> struct common_type_impl<T, T>
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{
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typedef T type;
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};
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// one of the operands is a class type, try conversions in both directions
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template<class T, class U> struct ct_class
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{
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BOOST_STATIC_CONSTANT( bool, ct = boost::is_class<T>::value || boost::is_union<T>::value );
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BOOST_STATIC_CONSTANT( bool, cu = boost::is_class<U>::value || boost::is_union<U>::value );
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BOOST_STATIC_CONSTANT( bool, value = ct || cu );
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};
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template<class T, class U> struct common_type_impl3;
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template<class T, class U> struct common_type_class: public boost::conditional<
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boost::is_convertible<T, U>::value && !boost::is_convertible<U, T>::value,
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boost::type_identity<U>,
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typename boost::conditional<
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boost::is_convertible<U, T>::value && !boost::is_convertible<T, U>::value,
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boost::type_identity<T>,
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common_type_impl3<T, U>
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>::type
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>::type
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{
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};
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template<class T, class U> struct common_type_impl: public boost::conditional<
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ct_class<T, U>::value,
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common_type_class<T, U>,
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common_type_impl3<T, U> >::type
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{
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};
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// pointers
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template<class T, class U> struct common_type_impl4;
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template<class T, class U> struct common_type_impl3: public boost::conditional<
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boost::is_pointer<T>::value || boost::is_pointer<U>::value,
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composite_pointer_type<T, U>,
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common_type_impl4<T, U> >::type
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{
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};
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// pointers to members
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template<class T, class U> struct common_type_impl5;
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template<class T, class U> struct common_type_impl4: public boost::conditional<
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boost::is_member_pointer<T>::value || boost::is_member_pointer<U>::value,
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composite_member_pointer_type<T, U>,
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common_type_impl5<T, U> >::type
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{
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};
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// arithmetic types (including class types w/ conversions to arithmetic and enums)
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template<class T, class U> struct common_type_impl5: public common_arithmetic_type<T, U>
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{
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};
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} // namespace type_traits_detail
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} // namespace boost
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#endif // #ifndef BOOST_TYPE_TRAITS_DETAIL_COMMON_TYPE_IMPL_HPP_INCLUDED
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