boost/fusion/support/detail/segmented_fold_until_impl.hpp
/*=============================================================================
Copyright (c) 2011 Eric Niebler
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
==============================================================================*/
#if !defined(BOOST_FUSION_SEGMENTED_FOLD_UNTIL_IMPL_HPP_INCLUDED)
#define BOOST_FUSION_SEGMENTED_FOLD_UNTIL_IMPL_HPP_INCLUDED
#include <boost/mpl/bool.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/utility/result_of.hpp>
#include <boost/type_traits/add_const.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/fusion/support/void.hpp>
#include <boost/fusion/container/list/cons_fwd.hpp>
#include <boost/fusion/sequence/intrinsic_fwd.hpp>
#include <boost/fusion/iterator/equal_to.hpp>
#include <boost/fusion/iterator/deref.hpp>
#include <boost/fusion/iterator/next.hpp>
#include <boost/fusion/support/is_segmented.hpp>
#include <boost/fusion/sequence/intrinsic/segments.hpp>
// fun(seq, state, context)
// seq: a non-segmented range
// state: the state of the fold so far
// context: the path to the current range
//
// returns: (state', fcontinue)
namespace boost { namespace fusion
{
template <typename First, typename Last>
struct iterator_range;
template <typename Context>
struct segmented_iterator;
namespace result_of
{
template <typename Cur, typename Context>
struct make_segmented_iterator
{
typedef
iterator_range<
Cur
, typename result_of::end<
typename remove_reference<
typename add_const<
typename result_of::deref<
typename Context::car_type::begin_type
>::type
>::type
>::type
>::type
>
range_type;
typedef
segmented_iterator<cons<range_type, Context> >
type;
};
}
template <typename Cur, typename Context>
typename result_of::make_segmented_iterator<Cur, Context>::type
make_segmented_iterator(Cur const& cur, Context const& context)
{
typedef result_of::make_segmented_iterator<Cur, Context> impl_type;
typedef typename impl_type::type type;
typedef typename impl_type::range_type range_type;
return type(cons<range_type, Context>(range_type(cur, fusion::end(*context.car.first)), context));
}
namespace detail
{
template <
typename Begin
, typename End
, typename State
, typename Context
, typename Fun
, bool IsEmpty
>
struct segmented_fold_until_iterate_skip_empty;
template <
typename Begin
, typename End
, typename State
, typename Context
, typename Fun
, bool IsDone = result_of::equal_to<Begin, End>::type::value
>
struct segmented_fold_until_iterate;
template <
typename Sequence
, typename State
, typename Context
, typename Fun
, bool IsSegmented = traits::is_segmented<Sequence>::type::value
>
struct segmented_fold_until_impl;
template <typename Segments, typename State, typename Context, typename Fun>
struct segmented_fold_until_on_segments;
//auto push_context(cur, end, context)
//{
// return push_back(context, segment_sequence(iterator_range(cur, end)));
//}
template <typename Cur, typename End, typename Context>
struct push_context
{
typedef iterator_range<Cur, End> range_type;
typedef cons<range_type, Context> type;
static type call(Cur const& cur, End const& end, Context const& context)
{
return cons<range_type, Context>(range_type(cur, end), context);
}
};
//auto make_segmented_iterator(cur, end, context)
//{
// return segmented_iterator(push_context(cur, end, context));
//}
//
//auto segmented_fold_until_impl(seq, state, context, fun)
//{
// if (is_segmented(seq))
// {
// segmented_fold_until_on_segments(segments(seq), state, context, fun);
// }
// else
// {
// return fun(seq, state, context);
// }
//}
template <
typename Sequence
, typename State
, typename Context
, typename Fun
, bool IsSegmented
>
struct segmented_fold_until_impl
{
typedef
segmented_fold_until_on_segments<
typename remove_reference<
typename add_const<
typename result_of::segments<Sequence>::type
>::type
>::type
, State
, Context
, Fun
>
impl;
typedef typename impl::type type;
typedef typename impl::continue_type continue_type;
static type call(Sequence& seq, State const& state, Context const& context, Fun const& fun)
{
return impl::call(fusion::segments(seq), state, context, fun);
}
};
template <
typename Sequence
, typename State
, typename Context
, typename Fun
>
struct segmented_fold_until_impl<Sequence, State, Context, Fun, false>
{
typedef
typename Fun::template apply<Sequence, State, Context>
apply_type;
typedef typename apply_type::type type;
typedef typename apply_type::continue_type continue_type;
static type call(Sequence& seq, State const& state, Context const& context, Fun const& fun)
{
return apply_type::call(seq, state, context, fun);
}
};
//auto segmented_fold_until_on_segments(segs, state, context, fun)
//{
// auto cur = begin(segs), end = end(segs);
// for (; cur != end; ++cur)
// {
// if (empty(*cur))
// continue;
// auto context` = push_context(cur, end, context);
// state = segmented_fold_until_impl(*cur, state, context`, fun);
// if (!second(state))
// return state;
// }
//}
template <typename Apply>
struct continue_wrap
{
typedef typename Apply::continue_type type;
};
template <typename Begin, typename End, typename State, typename Context, typename Fun, bool IsEmpty>
struct segmented_fold_until_iterate_skip_empty
{
// begin != end and !empty(*begin)
typedef
push_context<Begin, End, Context>
push_context_impl;
typedef
typename push_context_impl::type
next_context_type;
typedef
segmented_fold_until_impl<
typename remove_reference<
typename add_const<
typename result_of::deref<Begin>::type
>::type
>::type
, State
, next_context_type
, Fun
>
fold_recurse_impl;
typedef
typename fold_recurse_impl::type
next_state_type;
typedef
segmented_fold_until_iterate<
typename result_of::next<Begin>::type
, End
, next_state_type
, Context
, Fun
>
next_iteration_impl;
typedef
typename mpl::eval_if<
typename fold_recurse_impl::continue_type
, next_iteration_impl
, mpl::identity<next_state_type>
>::type
type;
typedef
typename mpl::eval_if<
typename fold_recurse_impl::continue_type
, continue_wrap<next_iteration_impl>
, mpl::identity<mpl::false_>
>::type
continue_type;
static type call(Begin const& beg, End const& end, State const& state
, Context const& context, Fun const& fun)
{
return call(beg, end, state, context, fun, typename fold_recurse_impl::continue_type());
}
static type call(Begin const& beg, End const& end, State const& state
, Context const& context, Fun const& fun, mpl::true_) // continue
{
return next_iteration_impl::call(
fusion::next(beg)
, end
, fold_recurse_impl::call(
*beg
, state
, push_context_impl::call(beg, end, context)
, fun)
, context
, fun);
}
static type call(Begin const& beg, End const& end, State const& state
, Context const& context, Fun const& fun, mpl::false_) // break
{
return fold_recurse_impl::call(
*beg
, state
, push_context_impl::call(beg, end, context)
, fun);
}
};
template <typename Begin, typename End, typename State, typename Context, typename Fun>
struct segmented_fold_until_iterate_skip_empty<Begin, End, State, Context, Fun, true>
{
typedef
segmented_fold_until_iterate<
typename result_of::next<Begin>::type
, End
, State
, Context
, Fun
>
impl;
typedef typename impl::type type;
typedef typename impl::continue_type continue_type;
static type call(Begin const& beg, End const& end, State const& state
, Context const& context, Fun const& fun)
{
return impl::call(fusion::next(beg), end, state, context, fun);
}
};
template <typename Begin, typename End, typename State, typename Context, typename Fun, bool IsDone>
struct segmented_fold_until_iterate
{
typedef
typename result_of::empty<
typename remove_reference<
typename result_of::deref<Begin>::type
>::type
>::type
empty_type;
typedef
segmented_fold_until_iterate_skip_empty<Begin, End, State, Context, Fun, empty_type::value>
impl;
typedef typename impl::type type;
typedef typename impl::continue_type continue_type;
static type call(Begin const& beg, End const& end, State const& state
, Context const& context, Fun const& fun)
{
return impl::call(beg, end, state, context, fun);
}
};
template <typename Begin, typename End, typename State, typename Context, typename Fun>
struct segmented_fold_until_iterate<Begin, End, State, Context, Fun, true>
{
typedef State type;
typedef mpl::true_ continue_type;
static type call(Begin const&, End const&, State const& state
, Context const&, Fun const&)
{
return state;
}
};
template <typename Segments, typename State, typename Context, typename Fun>
struct segmented_fold_until_on_segments
{
typedef
segmented_fold_until_iterate<
typename result_of::begin<Segments>::type
, typename result_of::end<Segments>::type
, State
, Context
, Fun
>
impl;
typedef typename impl::type type;
typedef typename impl::continue_type continue_type;
static type call(Segments& segs, State const& state, Context const& context, Fun const& fun)
{
return impl::call(fusion::begin(segs), fusion::end(segs), state, context, fun);
}
};
}
}}
#endif
