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aka_filter_iterator.hh
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/**
* @file aka_filter_iterator.hh
*
* @author Nicolas Richart
*
* @date creation jeu déc 12 2019
*
* @brief A Documented file.
*
* @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 <iterator>
#include <utility>
/* -------------------------------------------------------------------------- */
#ifndef AKA_FILTER_ITERATOR_H
#define AKA_FILTER_ITERATOR_H
#ifndef AKANTU_ITERATORS_NAMESPACE
#define AKANTU_ITERATORS_NAMESPACE akantu
#endif
namespace AKANTU_ITERATORS_NAMESPACE {
/* -------------------------------------------------------------------------- */
namespace iterators {
template <class filter_iterator_t, class container_iterator_t>
class FilterIterator {
public:
using value_type =
decltype(std::declval<container_iterator_t>().operator[](0));
using difference_type = typename filter_iterator_t::difference_type;
using pointer = std::decay_t<value_type> *;
using reference = value_type &;
using iterator_category = typename filter_iterator_t::iterator_category;
FilterIterator(filter_iterator_t filter_it,
container_iterator_t container_begin)
: filter_it(std::move(filter_it)),
container_begin(std::move(container_begin)) {}
FilterIterator(const FilterIterator &) = default;
FilterIterator & operator++() {
++filter_it;
return *this;
}
decltype(auto) operator*() {
auto container_it = this->container_begin + *this->filter_it;
return *container_it;
}
decltype(auto) operator*() const {
auto container_it = this->container_begin + *this->filter_it;
return *container_it;
}
bool operator==(const FilterIterator & other) const {
return (filter_it == other.filter_it) and
(container_begin == other.container_begin);
}
bool operator!=(const FilterIterator & other) const {
return filter_it != other.filter_it;
}
private:
filter_iterator_t filter_it;
container_iterator_t container_begin;
};
template <class filter_iterator_t, class container_iterator_t>
decltype(auto) make_filter_iterator(filter_iterator_t && filter_it,
container_iterator_t && container_begin) {
return FilterIterator<filter_iterator_t, container_iterator_t>(
std::forward<filter_iterator_t>(filter_it),
std::forward<container_iterator_t>(container_begin));
}
} // namespace iterators
namespace containers {
template <class filter_t, class Container> class FilterAdaptor {
public:
FilterAdaptor(filter_t && filter, Container && container)
: filter(std::forward<filter_t>(filter)),
container(std::forward<Container>(container)) {
static_assert(
std::is_same<typename decltype(container.begin())::iterator_category,
std::random_access_iterator_tag>::value,
"Containers must all have random iterators");
}
decltype(auto) begin() const {
return iterators::make_filter_iterator(filter.begin(), container.begin());
}
decltype(auto) begin() {
return iterators::make_filter_iterator(filter.begin(), container.begin());
}
decltype(auto) end() const {
return iterators::make_filter_iterator(filter.end(), container.begin());
}
decltype(auto) end() {
return iterators::make_filter_iterator(filter.end(), container.begin());
}
private:
filter_t filter;
Container container;
};
} // namespace containers
template <class filter_t, class Container>
decltype(auto) filter(filter_t && filter, Container && container) {
return containers::FilterAdaptor<filter_t, Container>(
std::forward<filter_t>(filter), std::forward<Container>(container));
}
} // namespace AKANTU_ITERATORS_NAMESPACE
namespace std {
template <class filter_iterator_t, class container_iterator_t>
struct iterator_traits<::AKANTU_ITERATORS_NAMESPACE::iterators::FilterIterator<
filter_iterator_t, container_iterator_t>> {
private:
using iterator_type =
typename ::AKANTU_ITERATORS_NAMESPACE::iterators::FilterIterator<
filter_iterator_t, container_iterator_t>;
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_FILTER_ITERATOR_H

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