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zip_iterator specialization for std::pair

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Signed-off-by: Kohei Takahashi <flast@flast.jp>
This commit is contained in:
Kohei Takahashi
2012-10-18 20:40:12 +09:00
parent acf9b4d4cf
commit 1ddaca8297
1 changed files with 56 additions and 2 deletions
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58
include/boost/iterator/zip_iterator.hpp
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@ -18,6 +18,7 @@
#include <boost/iterator/detail/minimum_category.hpp>
#include <utility> // for std::pair
#include <boost/fusion/adapted/boost_tuple.hpp> // for backward compatibility
#include <boost/type_traits/remove_reference.hpp>
@ -130,6 +131,16 @@ namespace boost {
{
};
// Specialization for std::pair
template<typename Iterator1, typename Iterator2>
struct tuple_of_references<std::pair<Iterator1, Iterator2> >
{
typedef std::pair<
typename iterator_reference<Iterator1>::type
, typename iterator_reference<Iterator2>::type
> type;
};
// Metafunction to obtain the minimal traversal tag in a tuple
// of iterators.
//
@ -148,6 +159,25 @@ namespace boost {
>::type type;
};
template<typename Iterator1, typename Iterator2>
struct minimum_traversal_category_in_iterator_tuple<std::pair<Iterator1, Iterator2> >
{
typedef typename pure_traversal_tag<
typename iterator_traversal<Iterator1>::type
>::type iterator1_traversal;
typedef typename pure_traversal_tag<
typename iterator_traversal<Iterator2>::type
>::type iterator2_traversal;
typedef typename minimum_category<
iterator1_traversal
, typename minimum_category<
iterator2_traversal
, random_access_traversal_tag
>::type
>::type type;
};
///////////////////////////////////////////////////////////////////
//
// Class zip_iterator_base
@ -196,6 +226,30 @@ namespace boost {
{
typedef int type;
};
template <typename reference>
struct converter
{
template <typename Seq>
static reference call(Seq seq)
{
typedef typename fusion::traits::tag_of<reference>::type tag;
return fusion::convert<tag>(seq);
}
};
template <typename Reference1, typename Reference2>
struct converter<std::pair<Reference1, Reference2> >
{
typedef std::pair<Reference1, Reference2> reference;
template <typename Seq>
static reference call(Seq seq)
{
return reference(
fusion::at_c<0>(seq)
, fusion::at_c<1>(seq));
}
};
}
/////////////////////////////////////////////////////////////////////
@ -252,8 +306,8 @@ namespace boost {
typename super_t::reference dereference() const
{
typedef typename super_t::reference reference;
typedef typename fusion::traits::tag_of<reference>::type tag;
return fusion::convert<tag>(fusion::transform(
typedef detail::converter<reference> gen;
return gen::call(fusion::transform(
get_iterator_tuple(),
detail::dereference_iterator()));
}