KFromNItr.h

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/*
  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef TRIGCOMPOSITEUTILS_KFROMNITR_H
#define TRIGCOMPOSITEUTILS_KFROMNITR_H
 
#include <iterator>
#include <vector>
 
namespace TrigCompositeUtils {
  class KFromNItr
  {
  public:
    using iterator_category = std::input_iterator_tag;
    using value_type = std::vector<std::size_t>;
    using reference = const value_type &;
    using pointer = const value_type *;
    using difference_type = std::ptrdiff_t;

    KFromNItr() = default;

    KFromNItr(std::size_t k, std::size_t N);

    std::size_t size() const { return m_current.size(); }

    void reset();

    bool exhausted() const;

    reference operator*() const;
    pointer operator->() const;

    KFromNItr &operator++();

    KFromNItr operator++(int);

    bool operator==(const KFromNItr &other) const;
    bool operator!=(const KFromNItr &other) const;
 
  private:
    std::size_t m_N{0};
    std::vector<std::size_t> m_current;
  }; //> end class KFromNItr
} //> end namespace TrigCompositeUtils
 
#endif //> !TRIGCOMPOSITEUTILS_KFROMNITR_H