109 lines
2.7 KiB
C++
109 lines
2.7 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_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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