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aka_concatenate_iterator.hh
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aka_concatenate_iterator.hh
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/**
* @file aka_concatenate_iterator.hh
*
* @author Nicolas Richart
*
* @date creation jeu déc 12 2019
*
* @brief implementation of arange
*
*
* Copyright (©) 2010-2011 EPFL (Ecole Polytechnique Fédérale de Lausanne)
* Laboratory (LSMS - Laboratoire de Simulation en Mécanique des Solides)
*
* akantu-iterators 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-iterators 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-iterators. If not, see <http://www.gnu.org/licenses/>.
*
*/
/* -------------------------------------------------------------------------- */
#include "aka_compatibilty_with_cpp_standard.hh"
#include "aka_iterator_tools.hh"
#include "aka_tuple_tools.hh"
/* -------------------------------------------------------------------------- */
#include <iterator>
#include <utility>
/* -------------------------------------------------------------------------- */
#ifndef AKA_CONCATENATE_ITERATOR_H
#define AKA_CONCATENATE_ITERATOR_H
#ifndef AKANTU_ITERATORS_NAMESPACE
#define AKANTU_ITERATORS_NAMESPACE akantu
#endif
namespace AKANTU_ITERATORS_NAMESPACE {
namespace iterators {
/* ------------------------------------------------------------------------ */
template <class... Iterators>
class ConcatIterator
: public details::CopyAssignmentEnabler<
aka::conjunction<std::is_copy_assignable<Iterators>...,
std::is_copy_constructible<Iterators>...>::value>,
public details::MoveAssignmentEnabler<
aka::conjunction<std::is_move_assignable<Iterators>...,
std::is_move_constructible<Iterators>...>::value> {
private:
using tuple_t = std::tuple<Iterators...>;
public:
using value_type =
std::tuple<typename std::iterator_traits<Iterators>::value_type...>;
using difference_type = std::common_type_t<
typename std::iterator_traits<Iterators>::difference_type...>;
using pointer =
std::tuple<typename std::iterator_traits<Iterators>::pointer...>;
using reference =
std::tuple<typename std::iterator_traits<Iterators>::reference...>;
using iterator_category = std::input_iterator_tag;
public:
explicit ConcatIterator(tuple_t iterators, tuple_t end_iterators)
: iterators(std::move(iterators)),
end_iterators(std::move(end_iterators)) {}
/* ---------------------------------------------------------------------- */
// input iterator ++it
ConcatIterator & operator++() {
auto && ends =
tuple::transform([](auto && a, auto && b) { return a == b; },
iterators, end_iterators);
auto && pos = tuple::find(ends, false);
++(tuple::dynamic_get(pos, iterators));
return *this;
}
// input iterator it++
ConcatIterator operator++(int) {
auto cpy = *this;
this->operator++();
return cpy;
}
// input iterator it != other_it
bool operator!=(const ConcatIterator & other) const {
return tuple::are_not_equal(iterators, other.iterators);
}
// input iterator dereference *it
decltype(auto) operator*() {
auto && ends =
tuple::transform([](auto && a, auto && b) { return a == b; },
iterators, end_iterators);
auto && pos = tuple::find(ends, false);
return *(tuple::dynamic_get(pos, iterators));
}
template <
class iterator_category_ = iterator_category,
std::enable_if_t<aka::is_iterator_category_at_least<
iterator_category_, std::forward_iterator_tag>::value> * = nullptr>
bool operator==(const ConcatIterator & other) const {
return not tuple::are_not_equal(iterators, other.iterators);
}
private:
tuple_t iterators;
tuple_t end_iterators;
};
} // namespace iterators
/* -------------------------------------------------------------------------- */
template <class... Iterators>
decltype(auto)
concat_iterator(std::tuple<Iterators...> && iterators_tuple,
std::tuple<Iterators...> && end_iterators_tuple) {
auto concat = iterators::ConcatIterator<Iterators...>(
std::forward<decltype(iterators_tuple)>(iterators_tuple),
std::forward<decltype(end_iterators_tuple)>(end_iterators_tuple));
return concat;
}
/* -------------------------------------------------------------------------- */
namespace containers {
template <class... Containers> class ConcatContainer {
using containers_t = std::tuple<Containers...>;
public:
explicit ConcatContainer(Containers &&... containers)
: containers(std::forward<Containers>(containers)...) {}
decltype(auto) begin() const {
return concat_iterator(
tuple::transform([](auto && c) { return c.begin(); },
std::forward<containers_t>(containers)),
tuple::transform([](auto && c) { return c.end(); },
std::forward<containers_t>(containers)));
}
decltype(auto) end() const {
return concat_iterator(
tuple::transform([](auto && c) { return c.end(); },
std::forward<containers_t>(containers)),
tuple::transform([](auto && c) { return c.end(); },
std::forward<containers_t>(containers)));
}
decltype(auto) begin() {
return concat_iterator(
tuple::transform([](auto && c) { return c.begin(); },
std::forward<containers_t>(containers)),
tuple::transform([](auto && c) { return c.end(); },
std::forward<containers_t>(containers)));
}
decltype(auto) end() {
return concat_iterator(
tuple::transform([](auto && c) { return c.end(); },
std::forward<containers_t>(containers)),
tuple::transform([](auto && c) { return c.end(); },
std::forward<containers_t>(containers)));
}
private:
containers_t containers;
};
/* ------------------------------------------------------------------------ */
template <class... Containers> decltype(auto) concat(Containers &&... conts) {
return containers::ConcatContainer<Containers...>(
std::forward<Containers>(conts)...);
}
} // namespace containers
} // namespace AKANTU_ITERATORS_NAMESPACE
namespace std {
template <typename... Its>
struct iterator_traits<
::AKANTU_ITERATORS_NAMESPACE::iterators::ConcatIterator<Its...>> {
private:
using iterator_type =
typename ::AKANTU_ITERATORS_NAMESPACE::iterators::ConcatIterator<Its...>;
public:
using iterator_category = typename iterator_type::iterator_category;
using value_type = typename iterator_type::value_type;
using difference_type = typename iterator_type::difference_type;
using pointer = typename iterator_type::pointer;
using reference = typename iterator_type::reference;
};
} // namespace std
#endif // __AKA_CONCATENATE_ITERATOR_H_

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