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https://github.com/boostorg/iterator.git
synced 2025-07-24 09:57:17 +02:00
try a better interface to indirect iterators
[SVN r9060]
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@ -658,39 +658,100 @@ struct indirect_iterator_policies : public default_iterator_policies
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{ return **x; }
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};
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// This macro definition is only temporary in this file
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# if !defined(BOOST_MSVC)
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# define BOOST_ARG_DEPENDENT_TYPENAME typename
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# else
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# define BOOST_ARG_DEPENDENT_TYPENAME
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# endif
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namespace detail {
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#if !defined(BOOST_MSVC)
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template <class T>
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struct value_type_of_value_type {
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typedef typename boost::detail::iterator_traits<T>::value_type outer_value;
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typedef typename boost::detail::iterator_traits<outer_value>::value_type type;
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};
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#else // Even this workaround doesn't fly :(
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template <class Value>
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struct inner_traits_select {
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template <class Iter,class Pointer, class Reference>
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struct rebind {
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struct traits {
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typedef typename boost::remove_const<Value>::type value_type;
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typedef Pointer pointer;
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typedef Reference reference;
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};
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};
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};
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struct no_value_type {};
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template <>
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struct inner_traits_select<no_value_type> {
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template <class Iter,class Pointer, class Reference>
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struct rebind {
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typedef typename boost::detail::iterator_traits<Iter>::value_type outer_value;
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typedef typename boost::detail::iterator_traits<outer_value> traits;
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};
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};
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#endif
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}
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template <class OuterIterator, // Mutable or Immutable, does not matter
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// Mutable reference and pointer type in traits class -> mutable indirect iterator;
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// Immutable reference and pointer type in traits class -> immutable indirect iterator
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class InnerTraits = boost::detail::iterator_traits<typename boost::detail::iterator_traits<OuterIterator>::value_type>
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class Value =
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#if !defined(BOOST_MSVC)
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BOOST_ARG_DEPENDENT_TYPENAME detail::value_type_of_value_type<OuterIterator>::type,
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#else
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detail::no_value_type,
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#endif
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class Pointer = Value*,
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class Reference = Value&
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>
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class indirect_iterator_generator
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{
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typedef boost::detail::iterator_traits<OuterIterator> OuterTraits;
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typedef typename OuterTraits::difference_type difference_type;
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typedef typename OuterTraits::iterator_category iterator_category;
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typedef boost::detail::iterator_traits<OuterIterator> outer_traits;
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typedef typename outer_traits::difference_type difference_type;
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typedef typename outer_traits::iterator_category iterator_category;
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typedef typename InnerTraits::value_type value_type;
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typedef typename InnerTraits::pointer pointer;
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typedef typename InnerTraits::reference reference;
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#if !defined(BOOST_MSVC)
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typedef typename boost::remove_const<Value>::type value_type;
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typedef Pointer pointer;
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typedef Reference reference;
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#else
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typedef detail::inner_traits_select<Value>::template
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rebind<OuterIterator,Pointer,Reference> inner_traits;
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typedef typename inner_traits::value_type value_type;
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typedef typename inner_traits::pointer pointer;
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typedef typename inner_traits::reference reference;
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#endif
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public:
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typedef boost::iterator<iterator_category, value_type, difference_type, pointer, reference> indirect_traits;
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typedef iterator_adaptor<OuterIterator, indirect_iterator_policies, indirect_traits> type;
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};
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template <class OuterIterator, // Mutable or Immutable, does not matter
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class ConstInnerIterator, // Immutable
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class ConstInnerTraits = boost::detail::iterator_traits<ConstInnerIterator>,
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class InnerTraits = boost::detail::iterator_traits<typename boost::detail::iterator_traits<OuterIterator>::value_type>
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class Value =
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#if !defined(BOOST_MSVC)
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BOOST_ARG_DEPENDENT_TYPENAME detail::value_type_of_value_type<OuterIterator>::type,
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#else
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detail::no_value_type,
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#endif
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class Pointer = Value*,
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class Reference = Value&,
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class ConstPointer = const Value*,
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class ConstReference = const Value&
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>
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struct indirect_iterator_pair_generator
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{
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typedef typename indirect_iterator_generator<OuterIterator,
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InnerTraits>::type iterator;
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Value, Pointer, Reference>::type iterator;
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typedef typename indirect_iterator_generator<OuterIterator,
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ConstInnerTraits>::type const_iterator;
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Value, ConstPointer, ConstReference>::type const_iterator;
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};
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#ifndef BOOST_NO_STD_ITERATOR_TRAITS
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# undef BOOST_ARG_DEPENDENT_TYPENAME
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# ifndef BOOST_NO_STD_ITERATOR_TRAITS
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template <class OuterIterator>
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inline typename indirect_iterator_generator<OuterIterator>::type
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make_indirect_iterator(OuterIterator base)
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@ -699,7 +760,7 @@ make_indirect_iterator(OuterIterator base)
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<OuterIterator>::type result_t;
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return result_t(base);
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}
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#endif
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# endif
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// Tried to allow InnerTraits to be provided by explicit template
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// argument to the function, but could not get it to work. -Jeremy Siek
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