tupleutility.hh

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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
// SPDX-FileCopyrightInfo: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
 
#ifndef DUNE_TUPLE_UTILITY_HH
#define DUNE_TUPLE_UTILITY_HH
 
#include <cstddef>
#include <tuple>
#include <type_traits>
#include <utility>
 
#include <dune/common/hybridutilities.hh>
#include <dune/common/typetraits.hh>
 
namespace Dune {
 
  template<class F, class ArgTuple, class I, I... i>
  decltype(auto) applyPartial(F&& f, ArgTuple&& args, std::integer_sequence<I, i...> /*indices*/)
  {
    return f(std::get<i>(args)...);
  }
 
  template<class T>
  struct TupleAccessTraits
  {
    typedef typename std::add_const<T>::type& ConstType;
    typedef T& NonConstType;
    typedef const typename std::remove_const<T>::type& ParameterType;
  };
 
  template<class T>
  struct TupleAccessTraits<T*>
  {
    typedef typename std::add_const<T>::type* ConstType;
    typedef T* NonConstType;
    typedef T* ParameterType;
  };
 
  template<class T>
  struct TupleAccessTraits<T&>
  {
    typedef T& ConstType;
    typedef T& NonConstType;
    typedef T& ParameterType;
  };
 
  template<class T>
  struct NullPointerInitialiser;
 
  template<class... Args>
  struct NullPointerInitialiser<std::tuple<Args...> >
  {
    typedef std::tuple<Args...> ResultType;
    static ResultType apply()
    {
      return ResultType(static_cast<Args>(nullptr)...);
    }
  };
 
  template<template <class> class TE, class T>
  struct ForEachType;
 
  template<template <class> class TE, class... Args>
  struct ForEachType<TE, std::tuple<Args...> >
  {
    typedef std::tuple<typename TE<Args>::Type...> Type;
  };
 
#ifndef DOXYGEN
  template<class Tuple, class Functor, std::size_t... I>
  inline auto genericTransformTupleBackendImpl(Tuple& t, Functor& f, const std::index_sequence<I...>& )
    -> std::tuple<decltype(f(std::get<I>(t)))...>
  {
    return std::tuple<decltype(f(std::get<I>(t)))...>(f(std::get<I>(t))...);
  }
 
  template<class... Args, class Functor>
  auto genericTransformTupleBackend(std::tuple<Args...>& t, Functor& f) ->
    decltype(genericTransformTupleBackendImpl(t, f,std::index_sequence_for<Args...>{}))
  {
    return genericTransformTupleBackendImpl(t, f,std::index_sequence_for<Args...>{});
  }
 
  template<class... Args, class Functor>
  auto genericTransformTupleBackend(const std::tuple<Args...>& t, Functor& f) ->
    decltype(genericTransformTupleBackendImpl(t, f, std::index_sequence_for<Args...>{}))
  {
    return genericTransformTupleBackendImpl(t, f, std::index_sequence_for<Args...>{});
  }
#endif
 
  template<class Tuple, class Functor>
  auto genericTransformTuple(Tuple&& t, Functor&& f) ->
    decltype(genericTransformTupleBackend(t, f))
  {
    return genericTransformTupleBackend(t, f);
  }
 
  template<template<class> class TE, class... Args>
  class TransformTupleFunctor
  {
    mutable std::tuple<Args&...> tup;
 
    template<class T, std::size_t... I>
    inline auto apply(T&& t, const std::index_sequence<I...>& ) ->
      decltype(TE<T>::apply(t,std::get<I>(tup)...)) const
    {
      return TE<T>::apply(t,std::get<I>(tup)...);
    }
 
  public:
    template<class T>
    struct TypeEvaluator : public TE<T>
    {};
 
    TransformTupleFunctor(Args&&... args)
      : tup(args...)
    { }
 
    template<class T>
    inline auto operator()(T&& t) ->
      decltype(this->apply(t,std::index_sequence_for<Args...>{})) const
    {
      return apply(t,std::index_sequence_for<Args...>{});
    }
  };
 
  template<template<class> class TE, class... Args>
  TransformTupleFunctor<TE, Args...> makeTransformTupleFunctor(Args&&... args)
  {
    return TransformTupleFunctor<TE, Args...>(args...);
  }
 
  template<template<class> class TypeEvaluator, class Tuple, class... Args>
  auto transformTuple(Tuple&& orig, Args&&... args) ->
    decltype(genericTransformTuple(orig, makeTransformTupleFunctor<TypeEvaluator>(args...)))
  {
    return genericTransformTuple(orig, makeTransformTupleFunctor<TypeEvaluator>(args...));
  }
 
 
  template<class T>
  struct AddRefTypeEvaluator
  {
    typedef T& Type;
    static Type apply(T& t)
    {
      return t;
    }
  };
 
 
  template<class T>
  struct AddPtrTypeEvaluator
  {
    typedef typename std::remove_reference<T>::type* Type;
    static Type apply(T& t)
    {
      return &t;
    }
  };
 
  // Specialization, in case the type is already a reference
  template<class T>
  struct AddPtrTypeEvaluator<T&>
  {
    typedef typename std::remove_reference<T>::type* Type;
    static Type apply(T& t)
    {
      return &t;
    }
  };
 
  template<int N, class Tuple>
  struct AtType
  {
    typedef typename std::tuple_element<std::tuple_size<Tuple>::value - N - 1, Tuple>::type Type;
  };
 
  template<int N>
  struct At
  {
    template<typename Tuple>
    static typename TupleAccessTraits<typename AtType<N, Tuple>::Type>::NonConstType
    get(Tuple& t)
    {
      return std::get<std::tuple_size<Tuple>::value - N - 1>(t);
    }
 
    template<typename Tuple>
    static typename TupleAccessTraits<typename AtType<N, Tuple>::Type>::ConstType
    get(const Tuple& t)
    {
      return std::get<std::tuple_size<Tuple>::value - N - 1>(t);
    }
  };
 
  template<class Tuple>
  struct PointerPairDeletor
  {
    template<typename... Ts>
    static void apply(std::tuple<Ts...>& t)
    {
      Hybrid::forEach(t,[&](auto&& ti){delete ti; ti=nullptr;});
    }
  };
 
  template<class Tuple, template<class> class Predicate, std::size_t start = 0,
      std::size_t size = std::tuple_size<Tuple>::value>
  class FirstPredicateIndex :
    public std::conditional<Predicate<typename std::tuple_element<start,
                Tuple>::type>::value,
        std::integral_constant<std::size_t, start>,
        FirstPredicateIndex<Tuple, Predicate, start+1> >::type
  {
    static_assert(std::tuple_size<Tuple>::value == size, "The \"size\" "
                       "template parameter of FirstPredicateIndex is an "
                       "implementation detail and should never be set "
                       "explicitly!");
  };
 
#ifndef DOXYGEN
  template<class Tuple, template<class> class Predicate, std::size_t size>
  class FirstPredicateIndex<Tuple, Predicate, size, size>
  {
    static_assert(AlwaysFalse<Tuple>::value, "None of the std::tuple element "
                       "types matches the predicate!");
  };
#endif // !DOXYGEN
 
  template<class T>
  struct IsType
  {
    template<class U>
    struct Predicate : public std::is_same<T, U> {};
  };
 
  template<class Tuple, class T, std::size_t start = 0>
  struct FirstTypeIndex :
    public FirstPredicateIndex<Tuple, IsType<T>::template Predicate, start>
  { };
 
  template<class Tuple, class T>
  struct PushBackTuple;
 
  template<class... Args, class T>
  struct PushBackTuple<typename std::tuple<Args...>, T>
  {
    typedef typename std::tuple<Args..., T> type;
  };
 
  template<class Tuple, class T>
  struct PushFrontTuple;
 
  template<class... Args, class T>
  struct PushFrontTuple<typename std::tuple<Args...>, T>
  {
    typedef typename std::tuple<T, Args...> type;
  };
 
  template<
      template <class, class> class F,
      class Tuple,
      class Seed=std::tuple<>,
      int N=std::tuple_size<Tuple>::value>
  struct ReduceTuple
  {
    typedef typename ReduceTuple<F, Tuple, Seed, N-1>::type Accumulated;
    typedef typename std::tuple_element<N-1, Tuple>::type Value;
 
    typedef typename F<Accumulated, Value>::type type;
  };
 
  template<
      template <class, class> class F,
      class Tuple,
      class Seed>
  struct ReduceTuple<F, Tuple, Seed, 0>
  {
    typedef Seed type;
  };
 
  template<class Head, class Tail>
  struct JoinTuples
  {
    typedef typename ReduceTuple<PushBackTuple, Tail, Head>::type type;
  };
 
  template<class Tuple>
  struct FlattenTuple
  {
    typedef typename ReduceTuple<JoinTuples, Tuple>::type type;
  };
 
}
 
#endif