boost/geometry/iterators/closing_iterator.hpp

// Boost.Geometry (aka GGL, Generic Geometry Library)

// Copyright (c) 2007-2011 Barend Gehrels, Amsterdam, the Netherlands.
// Copyright (c) 2008-2011 Bruno Lalande, Paris, France.
// Copyright (c) 2009-2011 Mateusz Loskot, London, UK.

// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
// (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.

// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_GEOMETRY_ITERATORS_CLOSING_ITERATOR_HPP
#define BOOST_GEOMETRY_ITERATORS_CLOSING_ITERATOR_HPP

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



namespace boost { namespace geometry
{

/*!
\brief Iterator which iterates through a range, but adds first element at end of the range
\tparam Range range on which this class is based on
\ingroup iterators
\note Use with "closing_iterator<Range> or "closing_iterator<Range const>
        to get non-const / const behaviour
\note This class is normally used from "closeable_view" if Close==true
*/
template <typename Range>
struct closing_iterator
    : public boost::iterator_facade
    <
        closing_iterator<Range>,
        typename boost::range_value<Range>::type const,
        boost::random_access_traversal_tag
    >
{
    /// Constructor including the range it is based on
    explicit inline closing_iterator(Range& range)
        : m_range(&range)
        , m_iterator(boost::begin(range))
        , m_end(boost::end(range))
        , m_size(boost::size(range))
        , m_index(0)
    {}

    /// Constructor to indicate the end of a range
    explicit inline closing_iterator(Range& range, bool)
        : m_range(&range)
        , m_iterator(boost::end(range))
        , m_end(boost::end(range))
        , m_size(boost::size(range))
        , m_index(m_size + 1)
    {}

    /// Default constructor
    explicit inline closing_iterator()
        : m_range(NULL)
        , m_size(0)
        , m_index(0)
    {}

    inline closing_iterator<Range>& operator=(closing_iterator<Range> const& source)
    {
        m_range = source.m_range;
        m_iterator = source.m_iterator;
        m_end = source.m_end;
        m_size = source.m_size;
        m_index = source.m_index;
        return *this;
    }

    typedef std::ptrdiff_t difference_type;

private:
    friend class boost::iterator_core_access;

    inline typename boost::range_value<Range>::type const& dereference() const
    {
        return *m_iterator;
    }

    inline difference_type distance_to(closing_iterator<Range> const& other) const
    {
        return other.m_index - this->m_index;
    }

    inline bool equal(closing_iterator<Range> const& other) const
    {
        return this->m_range == other.m_range
            && this->m_index == other.m_index;
    }

    inline void increment()
    {
        if (++m_index < m_size)
        {
            ++m_iterator;
        }
        else
        {
            update_iterator();
        }
    }

    inline void decrement()
    {
        if (m_index-- < m_size)
        {
            --m_iterator;
        }
        else
        {
            update_iterator();
        }
    }

    inline void advance(difference_type n)
    {
        if (m_index < m_size && m_index + n < m_size)
        {
            m_index += n;
            m_iterator += n;
        }
        else
        {
            m_index += n;
            update_iterator();
        }
    }

    inline void update_iterator()
    {
        this->m_iterator = m_index <= m_size
            ? boost::begin(*m_range) + (m_index % m_size)
            : boost::end(*m_range)
            ;
    }

    Range* m_range;
    typename boost::range_iterator<Range>::type m_iterator;
    typename boost::range_iterator<Range>::type m_end;
    difference_type m_size;
    difference_type m_index;
};


}} // namespace boost::geometry


#endif // BOOST_GEOMETRY_ITERATORS_CLOSING_ITERATOR_HPP