boost/fusion/iterator/detail/segmented_next_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_ITERATOR_NEXT_IMPL_HPP_INCLUDED)
#define BOOST_FUSION_SEGMENTED_ITERATOR_NEXT_IMPL_HPP_INCLUDED
#include <boost/type_traits/add_const.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/fusion/iterator/equal_to.hpp>
#include <boost/fusion/container/list/cons_fwd.hpp>
#include <boost/fusion/iterator/next.hpp>
#include <boost/fusion/iterator/deref.hpp>
namespace boost { namespace fusion
{
template <typename First, typename Second>
struct iterator_range;
template <typename Context>
struct segmented_iterator;
namespace detail
{
template <typename Sequence, typename Stack>
struct segmented_begin_impl;
//bool is_invalid(stack)
//{
// return empty(car(stack));
//}
template <typename Stack>
struct is_invalid
: result_of::equal_to<
typename Stack::car_type::begin_type,
typename Stack::car_type::end_type
>
{};
////Advance the first iterator in the seq at the
////top of a stack of iterator ranges. Return the
////new stack.
//auto pop_front_car(stack)
//{
// return cons(iterator_range(next(begin(car(stack))), end(car(stack))), cdr(stack));
//}
template <typename Stack>
struct pop_front_car
{
typedef
iterator_range<
typename result_of::next<
typename Stack::car_type::begin_type
>::type
, typename Stack::car_type::end_type
>
car_type;
typedef
cons<car_type, typename Stack::cdr_type>
type;
static type call(Stack const & stack)
{
return type(
car_type(fusion::next(stack.car.first), stack.car.last),
stack.cdr);
}
};
template <
typename Stack,
typename Next = typename pop_front_car<Stack>::type,
bool IsInvalid = is_invalid<Next>::value,
int StackSize = Stack::size::value>
struct segmented_next_impl_recurse;
// Handle the case where the top of the stack has no usable
//auto segmented_next_impl_recurse3(stack)
//{
// if (size(stack) == 1)
// return cons(iterator_range(end(car(stack)), end(car(stack))), nil_);
// else
// return segmented_next_impl_recurse(stack.cdr);
//}
template <
typename Stack,
int StackSize = Stack::size::value>
struct segmented_next_impl_recurse3
{
typedef segmented_next_impl_recurse<typename Stack::cdr_type> impl;
typedef typename impl::type type;
static type call(Stack const & stack)
{
return impl::call(stack.cdr);
}
};
template <typename Stack>
struct segmented_next_impl_recurse3<Stack, 1>
{
typedef typename Stack::car_type::end_type end_type;
typedef iterator_range<end_type, end_type> range_type;
typedef cons<range_type> type;
static type call(Stack const & stack)
{
return type(range_type(stack.car.last, stack.car.last));
}
};
//auto segmented_next_impl_recurse2(stack)
//{
// auto res = segmented_begin_impl(front(car(stack)), stack);
// if (is_invalid(res))
// return segmented_next_impl_recurse3(stack);
// else
// return res;
//}
template <
typename Stack,
typename Sequence =
typename remove_reference<
typename add_const<
typename result_of::deref<
typename Stack::car_type::begin_type
>::type
>::type
>::type,
typename Result =
typename segmented_begin_impl<Sequence, Stack>::type,
bool IsInvalid =
is_invalid<Result>::value>
struct segmented_next_impl_recurse2
{
typedef segmented_next_impl_recurse3<Stack> impl;
typedef typename impl::type type;
static type call(Stack const & stack)
{
return impl::call(stack);
}
};
template <typename Stack, typename Sequence, typename Result>
struct segmented_next_impl_recurse2<Stack, Sequence, Result, false>
{
typedef Result type;
static type call(Stack const & stack)
{
return segmented_begin_impl<Sequence, Stack>::call(*stack.car.first, stack);
}
};
//auto segmented_next_impl_recurse(stack)
//{
// auto next = pop_front_car(stack);
// if (is_invalid(next))
// if (1 == size(stack))
// return next;
// else
// return segmented_next_impl_recurse(cdr(stack));
// else
// return segmented_next_impl_recurse2(next)
//}
template <typename Stack, typename Next, bool IsInvalid, int StackSize>
struct segmented_next_impl_recurse
{
typedef
typename segmented_next_impl_recurse<typename Stack::cdr_type>::type
type;
static type call(Stack const& stack)
{
return segmented_next_impl_recurse<typename Stack::cdr_type>::call(stack.cdr);
}
};
template <typename Stack, typename Next>
struct segmented_next_impl_recurse<Stack, Next, true, 1>
{
typedef Next type;
static type call(Stack const & stack)
{
return pop_front_car<Stack>::call(stack);
}
};
template <typename Stack, typename Next, int StackSize>
struct segmented_next_impl_recurse<Stack, Next, false, StackSize>
{
typedef segmented_next_impl_recurse2<Next> impl;
typedef typename impl::type type;
static type call(Stack const & stack)
{
return impl::call(pop_front_car<Stack>::call(stack));
}
};
//auto segmented_next_impl(stack)
//{
// // car(stack) is a seq of values, not a seq of segments
// auto next = pop_front_car(stack);
// if (is_invalid(next))
// return segmented_next_impl_recurse(cdr(next));
// else
// return next;
//}
template <
typename Stack,
typename Next = typename pop_front_car<Stack>::type,
bool IsInvalid = is_invalid<Next>::value>
struct segmented_next_impl_aux
{
typedef segmented_next_impl_recurse<typename Stack::cdr_type> impl;
typedef typename impl::type type;
static type call(Stack const & stack)
{
return impl::call(stack.cdr);
}
};
template <typename Stack, typename Next>
struct segmented_next_impl_aux<Stack, Next, false>
{
typedef Next type;
static type call(Stack const & stack)
{
return pop_front_car<Stack>::call(stack);
}
};
template <typename Stack>
struct segmented_next_impl
: segmented_next_impl_aux<Stack>
{};
}
}}
#endif
