forked from boostorg/iterator
6e60ea7a88
The new eval_if_default helper replaces both ia_dflt_help and ia_eval_if_default helpers. Additionally, added a new if_default helper, which expands to the type or the default parameter directly. The new helpers are placed in separate headers which can be used without the iterator_adaptor template.
122 lines
3.1 KiB
C++
122 lines
3.1 KiB
C++
// (C) Copyright David Abrahams 2002.
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// (C) Copyright Jeremy Siek 2002.
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// (C) Copyright Thomas Witt 2002.
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// Distributed under the Boost Software License, Version 1.0. (See
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// 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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#ifndef BOOST_INDIRECT_ITERATOR_23022003THW_HPP
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#define BOOST_INDIRECT_ITERATOR_23022003THW_HPP
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#include <iterator>
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#include <type_traits>
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#include <boost/iterator/iterator_adaptor.hpp>
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#include <boost/iterator/enable_if_convertible.hpp>
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#include <boost/iterator/detail/eval_if_default.hpp>
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#include <boost/pointee.hpp>
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#include <boost/indirect_reference.hpp>
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#include <boost/core/use_default.hpp>
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namespace boost {
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namespace iterators {
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template< typename Iter, typename Value, typename Category, typename Reference, typename Difference >
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class indirect_iterator;
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namespace detail {
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template< typename Iter, typename Value, typename Category, typename Reference, typename Difference >
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struct indirect_base
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{
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using dereferenceable = typename std::iterator_traits< Iter >::value_type;
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using type = iterator_adaptor<
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indirect_iterator< Iter, Value, Category, Reference, Difference >,
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Iter,
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detail::eval_if_default_t<
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Value,
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pointee< dereferenceable >
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>,
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Category,
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detail::eval_if_default_t<
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Reference,
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detail::eval_if_default<
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Value,
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indirect_reference< dereferenceable >,
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std::add_lvalue_reference< Value >
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>
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>,
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Difference
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>;
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};
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} // namespace detail
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template<
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typename Iterator,
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typename Value = use_default,
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typename Category = use_default,
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typename Reference = use_default,
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typename Difference = use_default
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>
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class indirect_iterator :
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public detail::indirect_base<
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Iterator, Value, Category, Reference, Difference
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>::type
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{
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using super_t = typename detail::indirect_base<
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Iterator, Value, Category, Reference, Difference
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>::type;
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friend class iterator_core_access;
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public:
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indirect_iterator() = default;
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indirect_iterator(Iterator iter) :
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super_t(iter)
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{}
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template<
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typename Iterator2,
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typename Value2,
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typename Category2,
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typename Reference2,
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typename Difference2,
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typename = enable_if_convertible_t< Iterator2, Iterator >
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>
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indirect_iterator(indirect_iterator< Iterator2, Value2, Category2, Reference2, Difference2 > const& y) :
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super_t(y.base())
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{}
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private:
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typename super_t::reference dereference() const
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{
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return **this->base();
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}
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};
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template< typename Iter >
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inline indirect_iterator< Iter > make_indirect_iterator(Iter x)
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{
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return indirect_iterator< Iter >(x);
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}
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template< typename Value, typename Iter >
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inline indirect_iterator< Iter, Value > make_indirect_iterator(Iter x)
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{
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return indirect_iterator< Iter, Value >(x);
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}
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} // namespace iterators
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using iterators::indirect_iterator;
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using iterators::make_indirect_iterator;
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} // namespace boost
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#endif // BOOST_INDIRECT_ITERATOR_23022003THW_HPP
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