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Filename : statistics.hpp
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// Boost.Geometry Index
//
// R-tree visitor collecting basic statistics
//
// Copyright (c) 2011-2013 Adam Wulkiewicz, Lodz, Poland.
// Copyright (c) 2013 Mateusz Loskot, London, UK.
//
// This file was modified by Oracle on 2019.
// Modifications copyright (c) 2019 Oracle and/or its affiliates.
// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
//
// 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_INDEX_DETAIL_RTREE_UTILITIES_STATISTICS_HPP
#define BOOST_GEOMETRY_INDEX_DETAIL_RTREE_UTILITIES_STATISTICS_HPP

#include <algorithm>
#include <boost/tuple/tuple.hpp>

namespace boost { namespace geometry { namespace index { namespace detail { namespace rtree { namespace utilities {

namespace visitors {

template <typename MembersHolder>
struct statistics
    : public MembersHolder::visitor_const
{
    typedef typename MembersHolder::internal_node internal_node;
    typedef typename MembersHolder::leaf leaf;

    inline statistics()
        : level(0)
        , levels(1) // count root
        , nodes(0)
        , leaves(0)
        , values(0)
        , values_min(0)
        , values_max(0)
    {}

    inline void operator()(internal_node const& n)
    {
        typedef typename rtree::elements_type<internal_node>::type elements_type;
        elements_type const& elements = rtree::elements(n);
        
        ++nodes; // count node

        size_t const level_backup = level;
        ++level;

        levels += level++ > levels ? 1 : 0; // count level (root already counted)
                
        for (typename elements_type::const_iterator it = elements.begin();
            it != elements.end(); ++it)
        {
            rtree::apply_visitor(*this, *it->second);
        }
        
        level = level_backup;
    }

    inline void operator()(leaf const& n)
    {   
        typedef typename rtree::elements_type<leaf>::type elements_type;
        elements_type const& elements = rtree::elements(n);

        ++leaves; // count leaves
        
        std::size_t const v = elements.size();
        // count values spread per node and total
        values_min = (std::min)(values_min == 0 ? v : values_min, v);
        values_max = (std::max)(values_max, v);
        values += v;
    }
    
    std::size_t level;
    std::size_t levels;
    std::size_t nodes;
    std::size_t leaves;
    std::size_t values;
    std::size_t values_min;
    std::size_t values_max;
};

} // namespace visitors

template <typename Rtree> inline
boost::tuple<std::size_t, std::size_t, std::size_t, std::size_t, std::size_t, std::size_t>
statistics(Rtree const& tree)
{
    typedef utilities::view<Rtree> RTV;
    RTV rtv(tree);

    visitors::statistics<
        typename RTV::members_holder
    > stats_v;

    rtv.apply_visitor(stats_v);
    
    return boost::make_tuple(stats_v.levels, stats_v.nodes, stats_v.leaves, stats_v.values, stats_v.values_min, stats_v.values_max);
}

}}}}}} // namespace boost::geometry::index::detail::rtree::utilities

#endif // BOOST_GEOMETRY_INDEX_DETAIL_RTREE_UTILITIES_STATISTICS_HPP