boost/accumulators/framework/depends_on.hpp
///////////////////////////////////////////////////////////////////////////////
// depends_on.hpp
//
// Copyright 2005 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)
#ifndef BOOST_ACCUMULATORS_FRAMEWORK_DEPENDS_ON_HPP_EAN_28_10_2005
#define BOOST_ACCUMULATORS_FRAMEWORK_DEPENDS_ON_HPP_EAN_28_10_2005
#include <boost/version.hpp>
#include <boost/mpl/end.hpp>
#include <boost/mpl/map.hpp>
#include <boost/mpl/set.hpp>
#include <boost/mpl/copy.hpp>
#include <boost/mpl/fold.hpp>
#include <boost/mpl/size.hpp>
#include <boost/mpl/sort.hpp>
#include <boost/mpl/insert.hpp>
#include <boost/mpl/assert.hpp>
#include <boost/mpl/remove.hpp>
#include <boost/mpl/vector.hpp>
#include <boost/mpl/inherit.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/mpl/equal_to.hpp>
#include <boost/mpl/contains.hpp>
#include <boost/mpl/transform.hpp>
#include <boost/mpl/is_sequence.hpp>
#include <boost/mpl/placeholders.hpp>
#include <boost/mpl/insert_range.hpp>
#include <boost/mpl/back_inserter.hpp>
#include <boost/mpl/transform_view.hpp>
#include <boost/mpl/inherit_linearly.hpp>
#include <boost/type_traits/is_base_and_derived.hpp>
#include <boost/preprocessor/repetition/repeat.hpp>
#include <boost/preprocessor/repetition/enum_params.hpp>
#include <boost/preprocessor/facilities/intercept.hpp>
#include <boost/accumulators/accumulators_fwd.hpp>
#include <boost/fusion/include/next.hpp>
#include <boost/fusion/include/equal_to.hpp>
#include <boost/fusion/include/value_of.hpp>
#include <boost/fusion/include/mpl.hpp>
#include <boost/fusion/include/end.hpp>
#include <boost/fusion/include/begin.hpp>
#include <boost/fusion/include/cons.hpp>
namespace boost { namespace accumulators
{
///////////////////////////////////////////////////////////////////////////
// as_feature
template<typename Feature>
struct as_feature
{
typedef Feature type;
};
///////////////////////////////////////////////////////////////////////////
// weighted_feature
template<typename Feature>
struct as_weighted_feature
{
typedef Feature type;
};
///////////////////////////////////////////////////////////////////////////
// feature_of
template<typename Feature>
struct feature_of
{
typedef Feature type;
};
namespace detail
{
///////////////////////////////////////////////////////////////////////////
// feature_tag
template<typename Accumulator>
struct feature_tag
{
typedef typename Accumulator::feature_tag type;
};
template<typename Feature>
struct undroppable
{
typedef Feature type;
};
template<typename Feature>
struct undroppable<tag::droppable<Feature> >
{
typedef Feature type;
};
// For the purpose of determining whether one feature depends on another,
// disregard whether the feature is droppable or not.
template<typename A, typename B>
struct is_dependent_on
: is_base_and_derived<
typename feature_of<typename undroppable<B>::type>::type
, typename undroppable<A>::type
>
{};
template<typename Feature>
struct dependencies_of
{
typedef typename Feature::dependencies type;
};
// Should use mpl::insert_range, but doesn't seem to work with mpl sets
template<typename Set, typename Range>
struct set_insert_range
: mpl::fold<
Range
, Set
, mpl::insert<mpl::_1, mpl::_2>
>
{};
template<typename Features>
struct collect_abstract_features
: mpl::fold<
Features
, mpl::set0<>
, set_insert_range<
mpl::insert<mpl::_1, feature_of<mpl::_2> >
, collect_abstract_features<dependencies_of<mpl::_2> >
>
>
{};
template<typename Features>
struct depends_on_base
: mpl::inherit_linearly<
typename mpl::sort<
typename mpl::copy<
typename collect_abstract_features<Features>::type
, mpl::back_inserter<mpl::vector0<> >
>::type
, is_dependent_on<mpl::_1, mpl::_2>
>::type
// Don't inherit multiply from a feature
, mpl::if_<
is_dependent_on<mpl::_1, mpl::_2>
, mpl::_1
, mpl::inherit<mpl::_1, mpl::_2>
>
>::type
{
};
}
///////////////////////////////////////////////////////////////////////////
/// depends_on
template<BOOST_PP_ENUM_PARAMS(BOOST_ACCUMULATORS_MAX_FEATURES, typename Feature)>
struct depends_on
: detail::depends_on_base<
typename mpl::transform<
mpl::vector<BOOST_PP_ENUM_PARAMS(BOOST_ACCUMULATORS_MAX_FEATURES, Feature)>
, as_feature<mpl::_1>
>::type
>
{
typedef mpl::false_ is_weight_accumulator;
typedef
typename mpl::transform<
mpl::vector<BOOST_PP_ENUM_PARAMS(BOOST_ACCUMULATORS_MAX_FEATURES, Feature)>
, as_feature<mpl::_1>
>::type
dependencies;
};
namespace detail
{
template<typename Feature>
struct matches_feature
{
template<typename Accumulator>
struct apply
: is_same<
typename feature_of<typename as_feature<Feature>::type>::type
, typename feature_of<typename as_feature<typename feature_tag<Accumulator>::type>::type>::type
>
{};
};
template<typename Features, typename Accumulator>
struct contains_feature_of
{
typedef
mpl::transform_view<Features, feature_of<as_feature<mpl::_> > >
features_list;
typedef
typename feature_of<typename feature_tag<Accumulator>::type>::type
the_feature;
typedef
typename mpl::contains<features_list, the_feature>::type
type;
};
// This is to work around a bug in early versions of Fusion which caused
// a compile error if contains_feature_of<List, mpl::_> is used as a
// predicate to fusion::find_if
template<typename Features>
struct contains_feature_of_
{
template<typename Accumulator>
struct apply
: contains_feature_of<Features, Accumulator>
{};
};
template<
typename First
, typename Last
, bool is_empty = fusion::result_of::equal_to<First, Last>::value
>
struct build_acc_list;
template<typename First, typename Last>
struct build_acc_list<First, Last, true>
{
typedef fusion::nil type;
template<typename Args>
static fusion::nil
call(Args const &, First const&, Last const&)
{
return fusion::nil();
}
};
template<typename First, typename Last>
struct build_acc_list<First, Last, false>
{
typedef
build_acc_list<typename fusion::result_of::next<First>::type, Last>
next_build_acc_list;
typedef fusion::cons<
typename fusion::result_of::value_of<First>::type
, typename next_build_acc_list::type>
type;
template<typename Args>
static type
call(Args const &args, First const& f, Last const& l)
{
return type(args, next_build_acc_list::call(args, fusion::next(f), l));
}
};
namespace meta
{
template<typename Sequence>
struct make_acc_list
: build_acc_list<
typename fusion::result_of::begin<Sequence>::type
, typename fusion::result_of::end<Sequence>::type
>
{};
}
template<typename Sequence, typename Args>
typename meta::make_acc_list<Sequence>::type
make_acc_list(Sequence const &seq, Args const &args)
{
return meta::make_acc_list<Sequence>::call(args, fusion::begin(seq), fusion::end(seq));
}
///////////////////////////////////////////////////////////////////////////
// checked_as_weighted_feature
template<typename Feature>
struct checked_as_weighted_feature
{
typedef typename as_feature<Feature>::type feature_type;
typedef typename as_weighted_feature<feature_type>::type type;
// weighted and non-weighted flavors should provide the same feature.
BOOST_MPL_ASSERT((
is_same<
typename feature_of<feature_type>::type
, typename feature_of<type>::type
>
));
};
///////////////////////////////////////////////////////////////////////////
// as_feature_list
template<typename Features, typename Weight>
struct as_feature_list
: mpl::transform_view<Features, checked_as_weighted_feature<mpl::_1> >
{
};
template<typename Features>
struct as_feature_list<Features, void>
: mpl::transform_view<Features, as_feature<mpl::_1> >
{
};
///////////////////////////////////////////////////////////////////////////
// accumulator_wrapper
template<typename Accumulator, typename Feature>
struct accumulator_wrapper
: Accumulator
{
typedef Feature feature_tag;
accumulator_wrapper(accumulator_wrapper const &that)
: Accumulator(*static_cast<Accumulator const *>(&that))
{
}
template<typename Args>
accumulator_wrapper(Args const &args)
: Accumulator(args)
{
}
};
///////////////////////////////////////////////////////////////////////////
// to_accumulator
template<typename Feature, typename Sample, typename Weight>
struct to_accumulator
{
typedef
accumulator_wrapper<
typename mpl::apply2<typename Feature::impl, Sample, Weight>::type
, Feature
>
type;
};
template<typename Feature, typename Sample, typename Weight, typename Tag, typename AccumulatorSet>
struct to_accumulator<Feature, Sample, tag::external<Weight, Tag, AccumulatorSet> >
{
BOOST_MPL_ASSERT((is_same<Tag, void>));
BOOST_MPL_ASSERT((is_same<AccumulatorSet, void>));
typedef
accumulator_wrapper<
typename mpl::apply2<typename Feature::impl, Sample, Weight>::type
, Feature
>
accumulator_type;
typedef
typename mpl::if_<
typename Feature::is_weight_accumulator
, accumulator_wrapper<impl::external_impl<accumulator_type, tag::weights>, Feature>
, accumulator_type
>::type
type;
};
// BUGBUG work around an MPL bug wrt map insertion
template<typename FeatureMap, typename Feature>
struct insert_feature
: mpl::eval_if<
mpl::has_key<FeatureMap, typename feature_of<Feature>::type>
, mpl::identity<FeatureMap>
, mpl::insert<FeatureMap, mpl::pair<typename feature_of<Feature>::type, Feature> >
>
{
};
template<typename FeatureMap, typename Feature, typename Weight>
struct insert_dependencies
: mpl::fold<
as_feature_list<typename Feature::dependencies, Weight>
, FeatureMap
, insert_dependencies<
insert_feature<mpl::_1, mpl::_2>
, mpl::_2
, Weight
>
>
{
};
template<typename FeatureMap, typename Features, typename Weight>
struct insert_sequence
: mpl::fold< // BUGBUG should use insert_range, but doesn't seem to work for maps
as_feature_list<Features, Weight>
, FeatureMap
, insert_feature<mpl::_1, mpl::_2>
>
{
};
template<typename Features, typename Sample, typename Weight>
struct make_accumulator_tuple
{
typedef
typename mpl::fold<
as_feature_list<Features, Weight>
, mpl::map0<>
, mpl::if_<
mpl::is_sequence<mpl::_2>
, insert_sequence<mpl::_1, mpl::_2, Weight>
, insert_feature<mpl::_1, mpl::_2>
>
>::type
feature_map;
// for each element in the map, add its dependencies also
typedef
typename mpl::fold<
feature_map
, feature_map
, insert_dependencies<mpl::_1, mpl::second<mpl::_2>, Weight>
>::type
feature_map_with_dependencies;
// turn the map into a vector so we can sort it
typedef
typename mpl::insert_range<
mpl::vector<>
, mpl::end<mpl::vector<> >::type
, mpl::transform_view<feature_map_with_dependencies, mpl::second<mpl::_1> >
>::type
feature_vector_with_dependencies;
// sort the features according to which is derived from which
typedef
typename mpl::sort<
feature_vector_with_dependencies
, is_dependent_on<mpl::_2, mpl::_1>
>::type
sorted_feature_vector;
// From the vector of features, construct a vector of accumulators
typedef
typename mpl::transform<
sorted_feature_vector
, to_accumulator<mpl::_1, Sample, Weight>
>::type
type;
};
} // namespace detail
}} // namespace boost::accumulators
#endif