forked from boostorg/fusion
99 lines
2.8 KiB
C++
99 lines
2.8 KiB
C++
/*=============================================================================
|
|
Copyright (c) 2001-2006 Joel de Guzman
|
|
|
|
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(FUSION_FOLD_05052005_1211)
|
|
#define FUSION_FOLD_05052005_1211
|
|
|
|
#include <boost/mpl/bool.hpp>
|
|
#include <boost/mpl/apply.hpp>
|
|
#include <boost/mpl/identity.hpp>
|
|
#include <boost/fusion/iterator/equal_to.hpp>
|
|
#include <boost/fusion/sequence/intrinsic/begin.hpp>
|
|
#include <boost/fusion/sequence/intrinsic/end.hpp>
|
|
#include <boost/fusion/iterator/deref.hpp>
|
|
#include <boost/fusion/iterator/value_of.hpp>
|
|
#include <boost/fusion/iterator/next.hpp>
|
|
|
|
namespace boost { namespace fusion { namespace detail
|
|
{
|
|
// Unary arguments version
|
|
|
|
template <typename F>
|
|
struct apply_fold_result
|
|
{
|
|
template <typename Value, typename State>
|
|
struct apply
|
|
{
|
|
typedef typename F::template result<Value, State>::type type;
|
|
};
|
|
};
|
|
|
|
template <typename Iterator, typename State, typename F>
|
|
struct fold_apply
|
|
: mpl::apply<apply_fold_result<F>, typename result_of::value_of<Iterator>::type, State>
|
|
{};
|
|
|
|
template <typename First, typename Last, typename State, typename F>
|
|
struct static_fold;
|
|
|
|
template <typename First, typename Last, typename State, typename F>
|
|
struct next_result_of_fold
|
|
{
|
|
typedef typename
|
|
static_fold<
|
|
typename result_of::next<First>::type
|
|
, Last
|
|
, typename fold_apply<First, State, F>::type
|
|
, F
|
|
>::type
|
|
type;
|
|
};
|
|
|
|
template <typename First, typename Last, typename State, typename F>
|
|
struct static_fold
|
|
{
|
|
typedef typename
|
|
mpl::if_<
|
|
result_of::equal_to<First, Last>
|
|
, mpl::identity<State>
|
|
, next_result_of_fold<First, Last, State, F>
|
|
>::type
|
|
result;
|
|
|
|
typedef typename result::type type;
|
|
};
|
|
|
|
// terminal case
|
|
template <typename First, typename Last, typename State, typename F>
|
|
inline State const&
|
|
fold(First const&, Last const&, State const& state, F const&, mpl::true_)
|
|
{
|
|
return state;
|
|
}
|
|
|
|
// non-terminal case
|
|
template <typename First, typename Last, typename State, typename F>
|
|
inline typename static_fold<First, Last, State, F>::type
|
|
fold(
|
|
First const& first
|
|
, Last const& last
|
|
, State const& state
|
|
, F const& f
|
|
, mpl::false_)
|
|
{
|
|
return detail::fold(
|
|
fusion::next(first)
|
|
, last
|
|
, f(*first, state)
|
|
, f
|
|
, result_of::equal_to<typename result_of::next<First>::type, Last>()
|
|
);
|
|
}
|
|
}}}
|
|
|
|
#endif
|
|
|