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108 lines
2.7 KiB
108 lines
2.7 KiB
// 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_READABLE_ITERATOR_DWA2003112_HPP |
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# define IS_READABLE_ITERATOR_DWA2003112_HPP |
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#include <boost/mpl/bool.hpp> |
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#include <boost/detail/iterator.hpp> |
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#include <boost/type_traits/detail/bool_trait_def.hpp> |
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#include <boost/iterator/detail/any_conversion_eater.hpp> |
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// should be the last #include |
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#include <boost/iterator/detail/config_def.hpp> |
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#ifndef BOOST_NO_IS_CONVERTIBLE |
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namespace boost { |
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namespace detail |
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{ |
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// Guts of is_readable_iterator. Value is the iterator's value_type |
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// and the result is computed in the nested rebind template. |
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template <class Value> |
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struct is_readable_iterator_impl |
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{ |
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static char tester(Value&, int); |
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static char (& tester(any_conversion_eater, ...) )[2]; |
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template <class It> |
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struct rebind |
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{ |
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static It& x; |
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BOOST_STATIC_CONSTANT( |
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bool |
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, value = ( |
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sizeof( |
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is_readable_iterator_impl<Value>::tester(*x, 1) |
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) == 1 |
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) |
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); |
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}; |
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}; |
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#undef BOOST_READABLE_PRESERVER |
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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 <> |
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struct is_readable_iterator_impl<void> |
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{ |
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template <class It> |
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struct rebind : boost::mpl::false_ |
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{}; |
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}; |
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#ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS |
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template <> |
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struct is_readable_iterator_impl<const void> |
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{ |
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template <class It> |
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struct rebind : boost::mpl::false_ |
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{}; |
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}; |
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template <> |
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struct is_readable_iterator_impl<volatile void> |
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{ |
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template <class It> |
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struct rebind : boost::mpl::false_ |
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{}; |
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}; |
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template <> |
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struct is_readable_iterator_impl<const volatile void> |
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{ |
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template <class It> |
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struct rebind : boost::mpl::false_ |
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{}; |
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}; |
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#endif |
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// |
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// This level of dispatching is required for Borland. We might save |
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// an instantiation by removing it for others. |
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// |
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template <class It> |
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struct is_readable_iterator_impl2 |
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: is_readable_iterator_impl< |
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BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<It>::value_type const |
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>::template rebind<It> |
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{}; |
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} // namespace detail |
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// Define the trait with full mpl lambda capability and various broken |
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// compiler workarounds |
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BOOST_TT_AUX_BOOL_TRAIT_DEF1( |
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is_readable_iterator,T,::boost::detail::is_readable_iterator_impl2<T>::value) |
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} // namespace boost |
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#endif |
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#include <boost/iterator/detail/config_undef.hpp> |
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#endif // IS_READABLE_ITERATOR_DWA2003112_HPP
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