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// Copyright (c) 2020 GeometryFactory (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1/Principal_component_analysis/include/CGAL/Subiterator.h $
// $Id: include/CGAL/Subiterator.h b26b07a1242 $
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s) : Simon Giraudot
//
#ifndef CGAL_PCA_SUBITERATOR_H
#define CGAL_PCA_SUBITERATOR_H
#include <CGAL/license/Principal_component_analysis.h>
#include <boost/iterator/iterator_facade.hpp>
namespace CGAL
{
template <typename InputIterator, typename ValueType, int Size>
class Subiterator
: public boost::iterator_facade<Subiterator<InputIterator, ValueType, Size>,
ValueType,
std::input_iterator_tag>
{
public:
using Self = Subiterator<InputIterator, ValueType, Size>;
using Facade = boost::iterator_facade<Self, ValueType, std::input_iterator_tag>;
using Input_type = typename std::iterator_traits<InputIterator>::value_type;
using Output_type = ValueType;
using Converter = std::function<Output_type(const Input_type&, int)>;
private:
Converter m_converter;
int m_next_index;
InputIterator m_base;
mutable Output_type m_current;
public:
Subiterator() { }
Subiterator(InputIterator begin, const Converter& converter)
: m_converter(converter), m_next_index(0), m_base(begin)
{ }
Subiterator(InputIterator end)
: m_next_index(0), m_base(end)
{ }
private:
friend class boost::iterator_core_access;
void increment()
{
++ m_next_index;
if (m_next_index == Size)
{
++ m_base;
m_next_index = 0;
}
}
bool equal(const Self& other) const
{
return this->m_base == other.m_base && this->m_next_index == other.m_next_index;
}
Output_type& dereference() const
{
m_current = m_converter (*m_base, m_next_index);
return const_cast<Output_type&>(m_current);
}
};
template <typename ValueType, int Size, typename InputIterator>
Subiterator<InputIterator, ValueType, Size>
make_subiterator (InputIterator begin,
const typename Subiterator<InputIterator, ValueType, Size>::Converter& converter)
{
return Subiterator<InputIterator, ValueType, Size>(begin, converter);
}
template <typename ValueType, int Size, typename InputIterator>
Subiterator<InputIterator, ValueType, Size>
make_subiterator (InputIterator end)
{
return Subiterator<InputIterator, ValueType, Size>(end);
}
} // namespace CGAL
#endif // CGAL_PCA_SUBITERATOR_H
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