82 lines
1.9 KiB
C++
82 lines
1.9 KiB
C++
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// Copyright David Abrahams 2003. Use, modification and distribution is
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// subject to the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef IS_LVALUE_ITERATOR_DWA2003112_HPP
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#define IS_LVALUE_ITERATOR_DWA2003112_HPP
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#include <boost/iterator/detail/type_traits/conjunction.hpp>
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#include <iterator>
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#include <type_traits>
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namespace boost {
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namespace iterators {
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namespace detail {
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// Guts of is_lvalue_iterator. It is the iterator type and
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// Value is the iterator's value_type.
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template< typename It, typename Value >
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struct is_lvalue_iterator_impl :
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public detail::conjunction<
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std::is_convertible< decltype(*std::declval< It& >()), typename std::add_lvalue_reference< Value >::type >,
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std::is_lvalue_reference< decltype(*std::declval< It& >()) >
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>::type
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{
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};
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//
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// void specializations to handle std input and output iterators
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//
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template< typename It >
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struct is_lvalue_iterator_impl< It, void > :
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public std::false_type
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{
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};
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template< typename It >
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struct is_lvalue_iterator_impl< It, const void > :
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public std::false_type
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{
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};
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template< typename It >
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struct is_lvalue_iterator_impl< It, volatile void > :
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public std::false_type
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{
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};
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template< typename It >
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struct is_lvalue_iterator_impl< It, const volatile void > :
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public std::false_type
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{
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};
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} // namespace detail
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template< typename T >
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struct is_lvalue_iterator :
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public iterators::detail::is_lvalue_iterator_impl<
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T,
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typename std::iterator_traits< T >::value_type const
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>::type
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{
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};
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template< typename T >
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struct is_non_const_lvalue_iterator :
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public iterators::detail::is_lvalue_iterator_impl<
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T,
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typename std::iterator_traits< T >::value_type
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>::type
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{
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};
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} // namespace iterators
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using iterators::is_lvalue_iterator;
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using iterators::is_non_const_lvalue_iterator;
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} // namespace boost
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#endif // IS_LVALUE_ITERATOR_DWA2003112_HPP
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