meta.hpp

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//
// Copyright (C) 2014, 2015 Ableton AG, Berlin. All rights reserved.
//
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// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
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// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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#pragma once

#include <atria/xform/into.hpp>
#include <atria/xform/state_traits.hpp>
#include <atria/xform/reducing/last_rf.hpp>
#include <atria/meta/utils.hpp>
#include <atria/meta/eval.hpp>
#include <atria/meta/pack.hpp>

namespace atria {
namespace xform {

namespace detail {

struct output_of_rf_t
{
  template <typename StateT, typename ...InputTs>
  constexpr auto operator() (StateT, InputTs&&...) const
    -> meta::pack<InputTs&&...>;
};

} // namespace detail

template <typename XformT, typename... InputTs>
struct output_of
{
  using type = decltype(
    state_complete(
      std::declval<XformT>()(detail::output_of_rf_t{})(
        std::declval<meta::bottom>(),
        std::declval<InputTs>()...)));
};

template <typename XformT, typename... InputTs>
struct output_of<XformT, meta::pack<InputTs...> >
{
  using type = typename output_of<XformT, InputTs...>::type;
};

ABL_METAFUNCTION_T(output_of);

template <typename XformT, typename... InputTs>
struct result_of
{
  using type = estd::decay_t<decltype(
    state_complete(
      std::declval<XformT>()(last_rf)(
        std::declval<meta::bottom>(),
        std::declval<InputTs>()...)))>;
};


template <typename XformT, typename... InputTs>
struct result_of<XformT, meta::pack<InputTs...> >
{
  using type = typename result_of<XformT, InputTs...>::type;
};

ABL_METAFUNCTION_T(result_of);

} // namespace xform
} // namespace atria