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support for sequences weaker than Forward Sequence

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[SVN r37230]
This commit is contained in:
Tobias Schwinger
2007-03-19 18:13:24 +00:00
parent 798ebd7593
commit e82ddaed38
2 changed files with 28 additions and 20 deletions
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33
include/boost/fusion/sequence/view/zip_view/detail/strictest_traversal.hpp
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@ -15,7 +15,7 @@
#include <boost/fusion/sequence/intrinsic/mpl.hpp>
#include <boost/fusion/algorithm/iteration/fold.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/type_traits/is_convertible.hpp>
namespace boost { namespace fusion {
@ -25,6 +25,19 @@ namespace boost { namespace fusion {
namespace detail
{
template<typename Tag1, typename Tag2,
bool Tag1Stricter = boost::is_convertible<Tag2,Tag1>::value>
struct stricter_traversal
{
typedef Tag1 type;
};
template<typename Tag1, typename Tag2>
struct stricter_traversal<Tag1,Tag2,false>
{
typedef Tag2 type;
};
template<typename Next, typename StrictestSoFar>
struct strictest_traversal_impl
{
@ -32,23 +45,7 @@ namespace boost { namespace fusion {
typedef typename traits::category_of<
typename remove_reference<Next>::type>::type tag2;
typedef typename mpl::or_<
is_same<tag1, fusion::forward_traversal_tag>,
is_same<tag2, fusion::forward_traversal_tag> >::type
has_forward_traversal;
typedef typename mpl::or_<
is_same<tag1, fusion::bidirectional_traversal_tag>,
is_same<tag2, fusion::bidirectional_traversal_tag> >::type
has_bidirectional_traversal;
typedef typename mpl::if_<
has_forward_traversal,
forward_traversal_tag,
typename mpl::if_<
has_bidirectional_traversal,
bidirectional_traversal_tag,
random_access_traversal_tag>::type>::type type;
typedef typename stricter_traversal<tag1,tag2>::type type;
};
template<typename Sequence>

15
include/boost/fusion/sequence/view/zip_view/zip_view.hpp
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@ -47,10 +47,21 @@ namespace boost { namespace fusion {
struct seq_ref_size
{
template<typename Seq>
template<typename Seq,
typename SeqClass = typename remove_reference<Seq>::type,
bool HasSize = traits::is_forward<SeqClass>::value
>
struct result
: result_of::size<typename remove_reference<Seq>::type>
: result_of::size<SeqClass>
{};
static int const int_max = static_cast<int>(
static_cast<unsigned>(~0) >> 1);
template<typename Seq, typename SeqClass>
struct result<Seq, SeqClass, false>
: mpl::int_<int_max>
{};
};
struct poly_min