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aka_zip.hh
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/**
* @file aka_iterators.hh
*
* @author Nicolas Richart
*
* @date creation Wed Jul 19 2017
*
* @brief iterator interfaces
*
* @section LICENSE
*
* Copyright (©) 2010-2011 EPFL (Ecole Polytechnique Fédérale de Lausanne)
* Laboratory (LSMS - Laboratoire de Simulation en Mécanique des Solides)
*
* Akantu 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 of the License, or (at your option) any
* later version.
*
* Akantu 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 Lesser General Public License for more
* details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Akantu. If not, see <http://www.gnu.org/licenses/>.
*
*/
/* -------------------------------------------------------------------------- */
#include <tuple>
/* -------------------------------------------------------------------------- */
#ifndef __AKANTU_AKA_ITERATORS_HH__
#define __AKANTU_AKA_ITERATORS_HH__
namespace akantu {
namespace zip_ {
namespace details {
struct dereference_iterator {
template <class Iter> typename Iter::reference operator()(Iter & it) const {
return *it;
}
};
struct increment_iterator {
template <class Iter> void operator()(Iter & it) const { ++it; }
};
struct begin_container {
template <class Container>
decltype(auto) operator()(Container && cont) const {
return std::forward<Container>(cont).begin();
}
};
struct end_container {
template <class Container>
decltype(auto) operator()(Container && cont) const {
return std::forward<Container>(cont).end();
}
};
} // namespace details
} // namespace zip_
namespace tuple {
/* ------------------------------------------------------------------------ */
namespace details {
template <size_t N> struct Foreach {
template <class F, class Tuple>
static inline decltype(auto) transform_forward(F && func, Tuple && tuple) {
return std::tuple_cat(
Foreach<N - 1>::transform_forward(std::forward<F>(func),
std::forward<Tuple>(tuple)),
std::forward_as_tuple(std::forward<F>(func)(
std::get<N - 1>(std::forward<Tuple>(tuple)))));
}
template <class F, class Tuple>
static inline decltype(auto) transform(F && func, Tuple && tuple) {
return std::tuple_cat(
Foreach<N - 1>::transform(std::forward<F>(func),
std::forward<Tuple>(tuple)),
std::make_tuple(std::forward<F>(func)(
std::get<N - 1>(std::forward<Tuple>(tuple)))));
}
template <class F, class Tuple>
static inline void foreach (F && func, Tuple && tuple) {
Foreach<N - 1>::foreach (std::forward<F>(func),
std::forward<Tuple>(tuple));
std::forward<F>(func)(std::get<N - 1>(std::forward<Tuple>(tuple)));
}
template <class Tuple> static inline bool equal(Tuple && a, Tuple && b) {
if (not(std::get<N - 1>(std::forward<Tuple>(a)) ==
std::get<N - 1>(std::forward<Tuple>(b))))
return false;
return Foreach<N - 1>::equal(std::forward<Tuple>(a),
std::forward<Tuple>(b));
}
};
/* ------------------------------------------------------------------------ */
template <> struct Foreach<1> {
template <class F, class Tuple>
static inline decltype(auto) transform_forward(F && func, Tuple && tuple) {
return std::forward_as_tuple(
std::forward<F>(func)(std::get<0>(std::forward<Tuple>(tuple))));
}
template <class F, class Tuple>
static inline decltype(auto) transform(F && func, Tuple && tuple) {
return std::make_tuple(
std::forward<F>(func)(std::get<0>(std::forward<Tuple>(tuple))));
}
template <class F, class Tuple>
static inline void foreach (F && func, Tuple && tuple) {
std::forward<F>(func)(std::get<0>(std::forward<Tuple>(tuple)));
}
template <class Tuple> static inline bool equal(Tuple && a, Tuple && b) {
return std::get<0>(std::forward<Tuple>(a)) ==
std::get<0>(std::forward<Tuple>(b));
}
};
} // namespace details
/* ------------------------------------------------------------------------ */
template <class Tuple> bool are_equal(Tuple && a, Tuple && b) {
return details::Foreach<std::tuple_size<std::decay_t<Tuple>>::value>::equal(
std::forward<Tuple>(a), std::forward<Tuple>(b));
}
template <class F, class Tuple> void foreach (F && func, Tuple && tuple) {
details::Foreach<std::tuple_size<std::decay_t<Tuple>>::value>::foreach (
std::forward<F>(func), std::forward<Tuple>(tuple));
}
template <class F, class Tuple>
decltype(auto) transform_forward(F && func, Tuple && tuple) {
return details::Foreach<std::tuple_size<std::decay_t<Tuple>>::value>::
transform_forward(std::forward<F>(func), std::forward<Tuple>(tuple));
}
template <class F, class Tuple>
decltype(auto) transform(F && func, Tuple && tuple) {
return details::Foreach<std::tuple_size<std::decay_t<Tuple>>::value>::
transform(std::forward<F>(func), std::forward<Tuple>(tuple));
}
} // namespace tuple
namespace zip_ {
/* -------------------------------------------------------------------------- */
template <class... Iterators> class iterator {
private:
using tuple_t = std::tuple<Iterators...>;
public:
explicit iterator(tuple_t iterators) : iterators(std::move(iterators)) {}
decltype(auto) operator*() {
return tuple::transform_forward(details::dereference_iterator(), iterators);
}
iterator & operator++() {
tuple::foreach (details::increment_iterator(), iterators);
return *this;
}
bool operator==(const iterator & other) const {
return tuple::are_equal(iterators, other.iterators);
}
bool operator!=(const iterator & other) const {
return not operator==(other);
}
private:
tuple_t iterators;
};
} // namespace zip_
template <class... Iterators>
decltype(auto) zip_iterator(std::tuple<Iterators...> && iterators_tuple) {
auto zit = zip_::iterator<Iterators...>(std::move(iterators_tuple));
return zit;
}
namespace zip_ {
template <class... Containers> class Zip {
using containers_t = std::tuple<Containers &&...>;
public:
explicit Zip(Containers &&... containers)
: containers(std::forward_as_tuple(containers...)) {}
decltype(auto) begin() const {
return zip_iterator(tuple::transform(
details::begin_container(), std::forward<containers_t>(containers)));
}
decltype(auto) end() const {
return zip_iterator(tuple::transform(
details::end_container(), std::forward<containers_t>(containers)));
}
decltype(auto) begin() {
return zip_iterator(tuple::transform(
details::begin_container(), std::forward<containers_t>(containers)));
}
decltype(auto) end() {
return zip_iterator(tuple::transform(
details::end_container(), std::forward<containers_t>(containers)));
}
private:
containers_t containers;
};
} // namespace zip_
template <class... Containers> decltype(auto) zip(Containers &&... containers) {
return zip_::Zip<Containers...>(containers...);
}
} // namespace akantu
#endif /* __AKANTU_AKA_ITERATORS_HH__ */

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