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utilities.hh
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/**
* @file utilities.hh
*
* @author Till Junge <till.junge@epfl.ch>
*
* @date 17 Nov 2017
*
* @brief additions to the standard name space to anticipate C++17 features
*
* Copyright © 2017 Till Junge
*
* µSpectre is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3, or (at
* your option) any later version.
*
* µSpectre is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with µSpectre; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* * Boston, MA 02111-1307, USA.
*
* Additional permission under GNU GPL version 3 section 7
*
* If you modify this Program, or any covered work, by linking or combining it
* with proprietary FFT implementations or numerical libraries, containing parts
* covered by the terms of those libraries' licenses, the licensors of this
* Program grant you additional permission to convey the resulting work.
*/
#ifndef UTILITIES_H
#define UTILITIES_H
#include <tuple>
#ifdef NO_EXPERIMENTAL
# include <boost/optional.hpp>
#else
# include <experimental/optional>
#endif
namespace std_replacement {
namespace detail {
template <class T>
struct is_reference_wrapper : std::false_type {};
template <class U>
struct is_reference_wrapper<std::reference_wrapper<U>> : std::true_type {};
//! from cppreference
template <class Base, class T, class Derived, class... Args>
auto INVOKE(T Base::*pmf, Derived&& ref, Args&&... args)
noexcept(noexcept((std::forward<Derived>(ref).*pmf)(std::forward<Args>(args)...)))
-> std::enable_if_t<std::is_function<T>::value &&
std::is_base_of<Base, std::decay_t<Derived>>::value,
decltype((std::forward<Derived>(ref).*pmf)(std::forward<Args>(args)...))>
{
return (std::forward<Derived>(ref).*pmf)(std::forward<Args>(args)...);
}
//! from cppreference
template <class Base, class T, class RefWrap, class... Args>
auto INVOKE(T Base::*pmf, RefWrap&& ref, Args&&... args)
noexcept(noexcept((ref.get().*pmf)(std::forward<Args>(args)...)))
-> std::enable_if_t<std::is_function<T>::value &&
is_reference_wrapper<std::decay_t<RefWrap>>::value,
decltype((ref.get().*pmf)(std::forward<Args>(args)...))>
{
return (ref.get().*pmf)(std::forward<Args>(args)...);
}
//! from cppreference
template <class Base, class T, class Pointer, class... Args>
auto INVOKE(T Base::*pmf, Pointer&& ptr, Args&&... args)
noexcept(noexcept(((*std::forward<Pointer>(ptr)).*pmf)(std::forward<Args>(args)...)))
-> std::enable_if_t<std::is_function<T>::value &&
!is_reference_wrapper<std::decay_t<Pointer>>::value &&
!std::is_base_of<Base, std::decay_t<Pointer>>::value,
decltype(((*std::forward<Pointer>(ptr)).*pmf)(std::forward<Args>(args)...))>
{
return ((*std::forward<Pointer>(ptr)).*pmf)(std::forward<Args>(args)...);
}
//! from cppreference
template <class Base, class T, class Derived>
auto INVOKE(T Base::*pmd, Derived&& ref)
noexcept(noexcept(std::forward<Derived>(ref).*pmd))
-> std::enable_if_t<!std::is_function<T>::value &&
std::is_base_of<Base, std::decay_t<Derived>>::value,
decltype(std::forward<Derived>(ref).*pmd)>
{
return std::forward<Derived>(ref).*pmd;
}
//! from cppreference
template <class Base, class T, class RefWrap>
auto INVOKE(T Base::*pmd, RefWrap&& ref)
noexcept(noexcept(ref.get().*pmd))
-> std::enable_if_t<!std::is_function<T>::value &&
is_reference_wrapper<std::decay_t<RefWrap>>::value,
decltype(ref.get().*pmd)>
{
return ref.get().*pmd;
}
//! from cppreference
template <class Base, class T, class Pointer>
auto INVOKE(T Base::*pmd, Pointer&& ptr)
noexcept(noexcept((*std::forward<Pointer>(ptr)).*pmd))
-> std::enable_if_t<!std::is_function<T>::value &&
!is_reference_wrapper<std::decay_t<Pointer>>::value &&
!std::is_base_of<Base, std::decay_t<Pointer>>::value,
decltype((*std::forward<Pointer>(ptr)).*pmd)>
{
return (*std::forward<Pointer>(ptr)).*pmd;
}
//! from cppreference
template <class F, class... Args>
auto INVOKE(F&& f, Args&&... args)
noexcept(noexcept(std::forward<F>(f)(std::forward<Args>(args)...)))
-> std::enable_if_t<!std::is_member_pointer<std::decay_t<F>>::value,
decltype(std::forward<F>(f)(std::forward<Args>(args)...))>
{
return std::forward<F>(f)(std::forward<Args>(args)...);
}
} // namespace detail
//! from cppreference
template< class F, class... ArgTypes >
auto invoke(F&& f, ArgTypes&&... args)
// exception specification for QoI
noexcept(noexcept(detail::INVOKE(std::forward<F>(f), std::forward<ArgTypes>(args)...)))
-> decltype(detail::INVOKE(std::forward<F>(f), std::forward<ArgTypes>(args)...))
{
return detail::INVOKE(std::forward<F>(f), std::forward<ArgTypes>(args)...);
}
namespace detail {
//! from cppreference
template <class F, class Tuple, std::size_t... I>
constexpr decltype(auto) apply_impl(F &&f, Tuple &&t, std::index_sequence<I...>)
{
return std_replacement::invoke(std::forward<F>(f), std::get<I>(std::forward<Tuple>(t))...);
}
} // namespace detail
//! from cppreference
template <class F, class Tuple>
constexpr decltype(auto) apply(F &&f, Tuple &&t)
{
return detail::apply_impl
(std::forward<F>(f), std::forward<Tuple>(t),
std::make_index_sequence<std::tuple_size<std::decay_t<Tuple>>::value>{});
}
} //namespace std_replacement
namespace muSpectre {
namespace internal {
/**
* helper struct template to compute the type of a tuple with a
* given number of entries of the same type
*/
template <size_t size, typename T, typename... tail>
struct tuple_array_helper {
//! underlying tuple
using type = typename tuple_array_helper<size-1, T, T, tail...>::type;
};
/**
* helper struct template to compute the type of a tuple with a
* given number of entries of the same type
*/
template< typename T, typename... tail>
struct tuple_array_helper<0, T, tail...> {
//! underlying tuple
using type = std::tuple<tail...>;
};
/**
* helper struct for runtime index access to
* tuples. RecursionLevel indicates how much more we can recurse
* down
*/
template <class TupArr, size_t Index=0, size_t RecursionLevel=TupArr::Size-1>
struct Accessor {
using Stored_t = typename TupArr::Stored_t;
inline static Stored_t
get(const size_t & index, TupArr & container) {
if (index == Index) {
return std::get<Index>(container);
} else {
return Accessor<TupArr, Index+1, RecursionLevel-1>::get(index, container);
}
}
inline static const Stored_t
get(const size_t & index, const TupArr & container) {
if (index == Index) {
return std::get<Index>(container);
} else {
return Accessor<TupArr, Index+1, RecursionLevel-1>::get(index, container);
}
}
};
/**
* specialisation for recursion end
*/
template <class TupArr, size_t Index>
struct Accessor<TupArr, Index, 0> {
using Stored_t = typename TupArr::Stored_t;
inline static Stored_t
get(const size_t & index, TupArr & container) {
if (index == Index) {
return std::get<Index>(container);
} else {
std::stringstream err{};
err << "Index " << index << "is out of range.";
throw std::runtime_error(err.str());
}
}
inline static const Stored_t
get(const size_t & index, const TupArr & container) {
if (index == Index) {
return std::get<Index>(container);
} else {
std::stringstream err{};
err << "Index " << index << "is out of range.";
throw std::runtime_error(err.str());
}
}
};
/**
* helper struct that provides the tuple_array.
*/
template <typename T, size_t size>
struct tuple_array_provider {
//! tuple type that can be used (almost) like an `std::array`
class type: public tuple_array_helper<size, T>::type {
public:
//! short-hand
using Parent = typename tuple_array_helper<size, T>::type;
using Stored_t = T;
constexpr static size_t Size{size};
//! constructor
inline type(Parent && parent):Parent{parent}{};
//! element access
T operator[] (const size_t & index) {
return Accessor<type>::get(index, *this);
}
//! element access
const T operator[](const size_t & index) const {
return Accessor<type>::get(index, *this);
}
protected:
};
};
} // internal
/**
* This is a convenience structure to create a tuple of `nb_elem`
* entries of type `T`. It is named tuple_array, because it is
* somewhat similar to an `std::array<T, nb_elem>`. The reason for
* this structure is that the `std::array` is not allowed by the
* standard to store references (8.3.2 References, paragraph 5:
* "There shall be no references to references, no arrays of
* references, and no pointers to references.") use this, if you
* want to have a statically known number of references to store,
* and you wish to do so efficiently.
*/
template <typename T, size_t nb_elem>
using tuple_array = typename internal::tuple_array_provider<T, nb_elem>::type;
using std_replacement::apply;
/**
* emulation `std::optional` (a C++17 feature)
*/
template <class T>
#ifdef NO_EXPERIMENTAL
using optional = typename boost::optional<T>;
#else
using optional = typename std::experimental::optional<T>;
#endif
} // muSpectre
#endif /* UTILITIES_H */
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