needownoperatornew.h

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/* This file is part of the Tomographer project, which is distributed under the
 * terms of the MIT license.
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2016 ETH Zurich, Institute for Theoretical Physics, Philippe Faist
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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 */

#ifndef TOMOGRAPHER_TOOLS_NEEDOWNOPERATORNEW_H
#define TOMOGRAPHER_TOOLS_NEEDOWNOPERATORNEW_H

#include <type_traits>

#include <Eigen/Eigen> // EIGEN_MAKE_ALIGNED_OPERATOR_NEW

#include <tomographer2/tools/cxxutil.h> // tomo_internal::sfinae_yes, tomo_internal::sfinae_no


namespace Tomographer {
namespace Tools {

struct NoSpecialOperatorNewProvider {
  template<typename T>
  struct OperatorNewAllocatorType { typedef std::allocator<T> Type; };
};


namespace tomo_internal {

// see http://stackoverflow.com/a/9154394/1694896
template<typename T> static auto test_has_ownopnewprovidertype_member(int)
  -> typename sfinae_yes<typename T::OperatorNewProviderType>::yes&;
template<typename T> static auto test_has_ownopnewprovidertype_member(long)
  -> typename sfinae_no<>::no&;
template<typename T>
struct has_ownopnewprovidertype_member {
  static constexpr bool value = (sizeof(tomo_internal::test_has_ownopnewprovidertype_member<T>(0))
                                 == sizeof(typename tomo_internal::sfinae_yes<>::yes));
};
template<bool has_own_provider, typename T>
struct need_own_op_new_prov_helper {
  typedef NoSpecialOperatorNewProvider ProviderType;
};
template<typename T>
struct need_own_op_new_prov_helper<true, T> {
  typedef typename T::OperatorNewProviderType ProviderType;
};
} // namespace tomo_internal


template<typename... Types>
struct NeedOwnOperatorNew {
  // will be specialized appropriately.
};


template<typename T>
struct NeedOwnOperatorNew<T> {
  typedef typename tomo_internal::need_own_op_new_prov_helper<
    tomo_internal::has_ownopnewprovidertype_member<T>::value,
    T
    >::ProviderType
  ProviderType;

  typedef typename ProviderType::template OperatorNewAllocatorType<T>::Type AllocatorType;
};




//
// for Eigen types
//

struct EigenAlignedOperatorNewProvider {
public:
  EIGEN_MAKE_ALIGNED_OPERATOR_NEW ;
  typedef EigenAlignedOperatorNewProvider OperatorNewProviderType;

  template<typename T> struct OperatorNewAllocatorType {
    typedef Eigen::aligned_allocator<T> Type;
  };

#ifdef TOMOGRAPHER_TEST_TOOLS_NEEDOWNOPERATORNEW_DEBUG_MEMBERS
  // DEBUG: provide something we can test that it is indeed eigen-aligned 
  inline EigenAlignedOperatorNewProvider()
    : EigenAlignedOperatorNewIsActive(true)
  {
  }
  const bool EigenAlignedOperatorNewIsActive;
#endif
};


struct NeedEigenAlignedOperatorNew {
  typedef EigenAlignedOperatorNewProvider ProviderType;

  // prevent inadvertently inheriting this class instead of
  // EigenAlignedOperatorNewProvider:
  NeedEigenAlignedOperatorNew() = delete;
};


template<typename Scalar, int FixedRows, int FixedCols, int Options, int MaxRows, int MaxCols>
struct NeedOwnOperatorNew<Eigen::Matrix<Scalar,FixedRows,FixedCols,Options,MaxRows,MaxCols> >
  : public NeedEigenAlignedOperatorNew { };

template<typename Scalar, int FixedRows, int FixedCols, int Options, int MaxRows, int MaxCols>
struct NeedOwnOperatorNew<Eigen::Array<Scalar,FixedRows,FixedCols,Options,MaxRows,MaxCols> >
  : public NeedEigenAlignedOperatorNew { };




//
// Dark magic for allowing a struct to have several members of possibly different struct
// types (such as a ValueCalculator and a HistogramTypes), each of which might possibly
// require their own operator-new-providers; those super-structures should inherit from
// NeedOwnOperatorNew<Type1,Type2,Type3,...>::ProviderType , which resolves to the
// provider-type of all these types if they are the same (or if they don't require a
// provider-type).
//

template<typename Type1, typename Type2, typename... OtherTypes>
struct NeedOwnOperatorNew<Type1, Type2, OtherTypes...>;


namespace tomo_internal {

template<bool same_provider_type, bool t1_trivial_provider, bool t2_trivial_provider,
         typename Type1, typename Type2, typename... OtherTypes>
struct need_own_operator_new_combination_helper {
  // missing ProviderType member, will generate runtime error.
  static_assert(!same_provider_type && !t1_trivial_provider && !t2_trivial_provider,
                "ERROR: you have a type which requested a NeedOwnOperatorNew<T1,T2> "
                "with incompatible needs.") ;
};
// case same_provider_type == true
template<bool t1_trivial_provider, bool t2_trivial_provider,
         typename Type1, typename Type2, typename... OtherTypes>
struct need_own_operator_new_combination_helper<true, t1_trivial_provider, t2_trivial_provider,
                                                Type1, Type2, OtherTypes...> {
  // Type1 and Type2 have same provider, all ok, so continue and recurse on the other types:
  typedef typename NeedOwnOperatorNew<Type1, OtherTypes...>::ProviderType ProviderType;
};
// case t1_trivial_provider == true
template<bool t2_trivial_provider,
         typename Type1, typename Type2, typename... OtherTypes>
struct need_own_operator_new_combination_helper<false, true, t2_trivial_provider,
                                                Type1, Type2, OtherTypes...> {
  // all ok, use Type2's provider, and recurse on the other types
  typedef typename NeedOwnOperatorNew<Type2, OtherTypes...>::ProviderType ProviderType;
};
// case t2_trivial_provider == true (and t1_trivial_provider == false, otherwise see case above)
template<typename Type1, typename Type2, typename... OtherTypes>
struct need_own_operator_new_combination_helper<false, false, true,
                                                Type1, Type2, OtherTypes...> {
  // all ok, use Type2's provider, and recurse on the other types
  typedef typename NeedOwnOperatorNew<Type1, OtherTypes...>::ProviderType ProviderType;
};


} // namespace tomo_internal


template<typename Type1, typename Type2, typename... OtherTypes>
struct NeedOwnOperatorNew<Type1, Type2, OtherTypes...>
{
  typedef tomo_internal::need_own_operator_new_combination_helper<
    std::is_same<typename NeedOwnOperatorNew<Type1>::ProviderType,
                 typename NeedOwnOperatorNew<Type2>::ProviderType >::value,
    std::is_same<typename NeedOwnOperatorNew<Type1>::ProviderType,
                 NoSpecialOperatorNewProvider >::value,
    std::is_same<typename NeedOwnOperatorNew<Type2>::ProviderType,
                 NoSpecialOperatorNewProvider >::value,
    Type1, Type2, OtherTypes...
    > ProviderType;
};





} // namespace Tools
} // namespace Tomographer



#endif