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Removed MPL usage from facade_iterator_category.hpp.
This commit is contained in:
Andrey Semashev
parent
5f713e9b14
commit
d8ce9ddfc7
@ -4,36 +4,26 @@
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#ifndef FACADE_ITERATOR_CATEGORY_DWA20031118_HPP
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#define FACADE_ITERATOR_CATEGORY_DWA20031118_HPP
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# include <boost/core/use_default.hpp>
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# include <boost/iterator/iterator_categories.hpp>
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# include <boost/mpl/eval_if.hpp>
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# include <boost/mpl/identity.hpp>
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#include <iterator>
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#include <type_traits>
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#include <boost/mp11/utility.hpp>
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#include <boost/iterator/iterator_categories.hpp>
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#include <boost/iterator/detail/type_traits/conjunction.hpp>
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#include <boost/iterator/detail/type_traits/disjunction.hpp>
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#include <boost/iterator/detail/config_def.hpp> // try to keep this last
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# ifdef BOOST_ITERATOR_REF_CONSTNESS_KILLS_WRITABILITY
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# include <boost/detail/indirect_traits.hpp>
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# endif
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//
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// iterator_category deduction for iterator_facade
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//
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namespace boost {
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namespace iterators {
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using boost::use_default;
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namespace detail {
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struct input_output_iterator_tag
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: std::input_iterator_tag
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struct input_output_iterator_tag :
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public std::input_iterator_tag
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{
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// Using inheritance for only input_iterator_tag helps to avoid
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// ambiguities when a stdlib implementation dispatches on a
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@ -47,21 +37,35 @@ struct input_output_iterator_tag
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}
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};
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#ifdef BOOST_ITERATOR_REF_CONSTNESS_KILLS_WRITABILITY
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template< typename T >
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struct is_const_lvalue_reference :
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public std::false_type
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{};
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template< typename T >
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struct is_const_lvalue_reference< T const& > :
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public std::true_type
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{};
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#endif // BOOST_ITERATOR_REF_CONSTNESS_KILLS_WRITABILITY
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//
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// True iff the user has explicitly disabled writability of this
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// iterator. Pass the iterator_facade's Value parameter and its
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// nested ::reference type.
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//
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template <class ValueParam, class Reference>
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struct iterator_writability_disabled
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template< typename ValueParam, typename Reference >
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struct iterator_writability_disabled :
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# ifdef BOOST_ITERATOR_REF_CONSTNESS_KILLS_WRITABILITY // Adding Thomas' logic?
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: disjunction<
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std::is_const<Reference>
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, std::integral_constant<bool, boost::detail::indirect_traits::is_reference_to_const<Reference>::value>
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, std::is_const<ValueParam>
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public disjunction<
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is_const_lvalue_reference<Reference>,
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std::is_const<Reference>,
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std::is_const<ValueParam>
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>
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# else
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: std::is_const<ValueParam>
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public std::is_const<ValueParam>
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# endif
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{};
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@ -74,69 +78,68 @@ struct iterator_writability_disabled
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// to output_iterator_tag.
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//
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// Change at: https://svn.boost.org/trac/boost/changeset/21683
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template <class Traversal, class ValueParam, class Reference>
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template< typename Traversal, typename ValueParam, typename Reference >
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struct iterator_facade_default_category
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: mpl::eval_if<
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{
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using type = typename mp11::mp_if<
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detail::conjunction<
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std::is_reference<Reference>
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, std::is_convertible<Traversal,forward_traversal_tag>
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>
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, mpl::eval_if<
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std::is_convertible<Traversal,random_access_traversal_tag>
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, mpl::identity<std::random_access_iterator_tag>
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, std::conditional<
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std::is_convertible<Traversal,bidirectional_traversal_tag>::value
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, std::bidirectional_iterator_tag
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, std::forward_iterator_tag
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>
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>
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, mpl::eval_if<
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std::is_reference<Reference>,
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std::is_convertible<Traversal, forward_traversal_tag>
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>,
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mp11::mp_defer<
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mp11::mp_cond,
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std::is_convertible<Traversal, random_access_traversal_tag>, std::random_access_iterator_tag,
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std::is_convertible<Traversal, bidirectional_traversal_tag>, std::bidirectional_iterator_tag,
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std::true_type, std::forward_iterator_tag
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>,
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mp11::mp_defer<
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mp11::mp_if,
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detail::conjunction<
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std::is_convertible<Traversal, single_pass_traversal_tag>
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std::is_convertible<Traversal, single_pass_traversal_tag>,
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// check for readability
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, std::is_convertible<Reference, ValueParam>
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std::is_convertible<Reference, ValueParam>
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>,
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std::input_iterator_tag,
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Traversal
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>
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, mpl::identity<std::input_iterator_tag>
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, mpl::identity<Traversal>
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>
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>
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{
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>::type;
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};
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template< typename Traversal, typename ValueParam, typename Reference >
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using iterator_facade_default_category_t = typename iterator_facade_default_category<Traversal, ValueParam, Reference>::type;
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// True iff T is convertible to an old-style iterator category.
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template <class T>
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struct is_iterator_category
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: disjunction<
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std::is_convertible<T,std::input_iterator_tag>
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, std::is_convertible<T,std::output_iterator_tag>
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template< typename T >
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struct is_iterator_category :
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public disjunction<
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std::is_convertible<T, std::input_iterator_tag>,
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std::is_convertible<T, std::output_iterator_tag>
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>
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{
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};
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template <class T>
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struct is_iterator_traversal
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: std::is_convertible<T,incrementable_traversal_tag>
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{};
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template< typename T >
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struct is_iterator_traversal :
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public std::is_convertible<T, incrementable_traversal_tag>
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{};
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//
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// A composite iterator_category tag convertible to Category (a pure
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// old-style category) and Traversal (a pure traversal tag).
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// Traversal must be a strict increase of the traversal power given by
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// Category.
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//
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template <class Category, class Traversal>
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struct iterator_category_with_traversal
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: Category, Traversal
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template< typename Category, typename Traversal >
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struct iterator_category_with_traversal :
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public Category,
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public Traversal
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{
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// Make sure this isn't used to build any categories where
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// convertibility to Traversal is redundant. Should just use the
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// Category element in that case.
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static_assert(
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!std::is_convertible<
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typename iterator_category_to_traversal<Category>::type
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, Traversal
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>::value,
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!std::is_convertible<iterator_category_to_traversal_t<Category>, Traversal>::value,
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"Category transformed to corresponding traversal must be convertible to Traversal."
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);
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@ -148,36 +151,37 @@ struct iterator_category_with_traversal
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// Computes an iterator_category tag whose traversal is Traversal and
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// which is appropriate for an iterator
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template <class Traversal, class ValueParam, class Reference>
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template< typename Traversal, typename ValueParam, typename Reference >
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struct facade_iterator_category_impl
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{
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static_assert(!is_iterator_category<Traversal>::value, "Traversal must not be an STL iterator category.");
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typedef typename iterator_facade_default_category<
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Traversal,ValueParam,Reference
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>::type category;
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using category = iterator_facade_default_category_t<Traversal, ValueParam, Reference>;
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typedef typename std::conditional<
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using type = typename std::conditional<
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std::is_same<
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Traversal
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, typename iterator_category_to_traversal<category>::type
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>::value
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, category
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, iterator_category_with_traversal<category,Traversal>
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>::type type;
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Traversal,
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typename iterator_category_to_traversal<category>::type
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>::value,
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category,
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iterator_category_with_traversal<category, Traversal>
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>::type;
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};
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template< typename Traversal, typename ValueParam, typename Reference >
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using facade_iterator_category_impl_t = typename facade_iterator_category_impl<Traversal, ValueParam, Reference>::type;
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//
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// Compute an iterator_category for iterator_facade
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//
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template <class CategoryOrTraversal, class ValueParam, class Reference>
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template< typename CategoryOrTraversal, typename ValueParam, typename Reference >
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struct facade_iterator_category
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: mpl::eval_if<
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is_iterator_category<CategoryOrTraversal>
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, mpl::identity<CategoryOrTraversal> // old-style categories are fine as-is
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, facade_iterator_category_impl<CategoryOrTraversal,ValueParam,Reference>
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>
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{
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using type = mp11::mp_eval_if<
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is_iterator_category<CategoryOrTraversal>,
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CategoryOrTraversal, // old-style categories are fine as-is
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facade_iterator_category_impl_t, CategoryOrTraversal, ValueParam, Reference
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>;
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};
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}}} // namespace boost::iterators::detail
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