RandomIter.h

Go to the documentation of this file.

#ifndef WIRECELLUTIL_RANDOMITER
#define WIRECELLUTIL_RANDOMITER

#include <boost/iterator/iterator_categories.hpp>
#include <boost/iterator/iterator_facade.hpp>

namespace WireCell {

template <typename Container, typename  Value>
struct RandomIter : public boost::iterator_facade<
    RandomIter<Container, Value>,
    Value,
    boost::random_access_traversal_tag
    >
{
    // Constructor for begin()
    explicit RandomIter(Container& array)
        : m_array(array)
        , m_index(0)
    {}

    // Constructor for end(), bool is just a maker
    explicit RandomIter(bool, Container& array)
        : m_array(array)
        , m_index(array.size())
    {}

private:
    friend class boost::iterator_core_access;

    Container & m_array;
    int m_index;

    bool equal(RandomIter<Container, Value> const& other) const
    {
        return this->m_index == other.m_index;
    }

    typedef boost::iterator_facade<
        RandomIter<Container, Value>,
        Value,
        boost::random_access_traversal_tag
        > facade;
    typename facade::difference_type distance_to(RandomIter const& other) const {
       return other.m_index - this->m_index;
    }

    void advance(typename facade::difference_type n)
    {
        m_index += n;
        if (m_index >= (int)m_array.size() || m_index < 0) {
            m_index = m_array.size();
        }
    }

    void increment() {
        advance(1);
    }

    void decrement() {
        advance(-1);
    }

    // const and non-const dereference of this iterator
    Value& dereference() const {
        return m_array.at(m_index);
    }
};

}

#endif