478 lines
20 KiB
C++
478 lines
20 KiB
C++
// Boost.Geometry Index
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//
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// R-tree linear split algorithm implementation
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//
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// Copyright (c) 2008 Federico J. Fernandez.
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// Copyright (c) 2011-2022 Adam Wulkiewicz, Lodz, Poland.
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//
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// This file was modified by Oracle on 2019-2020.
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// Modifications copyright (c) 2019-2020 Oracle and/or its affiliates.
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// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
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//
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// Use, modification and distribution is subject to the Boost Software License,
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_GEOMETRY_INDEX_DETAIL_RTREE_LINEAR_REDISTRIBUTE_ELEMENTS_HPP
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#define BOOST_GEOMETRY_INDEX_DETAIL_RTREE_LINEAR_REDISTRIBUTE_ELEMENTS_HPP
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#include <type_traits>
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#include <boost/core/ignore_unused.hpp>
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#include <boost/geometry/core/static_assert.hpp>
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#include <boost/geometry/index/detail/algorithms/bounds.hpp>
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#include <boost/geometry/index/detail/algorithms/content.hpp>
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#include <boost/geometry/index/detail/bounded_view.hpp>
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#include <boost/geometry/index/detail/rtree/node/node.hpp>
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#include <boost/geometry/index/detail/rtree/visitors/insert.hpp>
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#include <boost/geometry/index/detail/rtree/visitors/is_leaf.hpp>
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namespace boost { namespace geometry { namespace index {
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namespace detail { namespace rtree {
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namespace linear {
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template <typename R, typename T>
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inline R difference_dispatch(T const& from, T const& to, std::false_type /*is_unsigned*/)
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{
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return to - from;
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}
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template <typename R, typename T>
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inline R difference_dispatch(T const& from, T const& to, std::true_type /*is_unsigned*/)
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{
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return from <= to ? R(to - from) : -R(from - to);
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}
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template <typename R, typename T>
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inline R difference(T const& from, T const& to)
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{
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BOOST_GEOMETRY_STATIC_ASSERT((! std::is_unsigned<R>::value),
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"Result can not be an unsigned type.",
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R);
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return difference_dispatch<R>(from, to, std::is_unsigned<T>());
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}
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// TODO: awulkiew
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// In general, all aerial Indexables in the tree with box-like nodes will be analyzed as boxes
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// because they must fit into larger box. Therefore the algorithm could be the same for Bounds type.
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// E.g. if Bounds type is sphere, Indexables probably should be analyzed as spheres.
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// 1. View could be provided to 'see' all Indexables as Bounds type.
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// Not ok in the case of big types like Ring, however it's possible that Rings won't be supported,
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// only simple types. Even then if we consider storing Box inside the Sphere we must calculate
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// the bounding sphere 2x for each box because there are 2 loops. For each calculation this means
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// 4-2d or 8-3d expansions or -, / and sqrt().
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// 2. Additional container could be used and reused if the Indexable type is other than the Bounds type.
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// IMPORTANT!
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// Still probably the best way would be providing specialized algorithms for each Indexable-Bounds pair!
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// Probably on pick_seeds algorithm level - For Bounds=Sphere seeds would be choosen differently
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// TODO: awulkiew
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// there are loops inside find_greatest_normalized_separation::apply()
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// iteration is done for each DimensionIndex.
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// Separations and seeds for all DimensionIndex(es) could be calculated at once, stored, then the greatest would be choosen.
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// The following struct/method was adapted for the preliminary version of the R-tree. Then it was called:
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// void find_normalized_separations(std::vector<Box> const& boxes, T& separation, unsigned int& first, unsigned int& second) const
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template <typename Elements, typename Parameters, typename Translator, typename Tag, size_t DimensionIndex>
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struct find_greatest_normalized_separation
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{
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typedef typename Elements::value_type element_type;
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typedef typename rtree::element_indexable_type<element_type, Translator>::type indexable_type;
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typedef typename coordinate_type<indexable_type>::type coordinate_type;
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typedef std::conditional_t
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<
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std::is_integral<coordinate_type>::value,
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double,
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coordinate_type
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> separation_type;
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typedef typename geometry::point_type<indexable_type>::type point_type;
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typedef geometry::model::box<point_type> bounds_type;
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typedef index::detail::bounded_view
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<
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indexable_type, bounds_type,
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typename index::detail::strategy_type<Parameters>::type
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> bounded_view_type;
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static inline void apply(Elements const& elements,
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Parameters const& parameters,
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Translator const& translator,
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separation_type & separation,
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size_t & seed1,
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size_t & seed2)
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{
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const size_t elements_count = parameters.get_max_elements() + 1;
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BOOST_GEOMETRY_INDEX_ASSERT(elements.size() == elements_count, "unexpected number of elements");
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BOOST_GEOMETRY_INDEX_ASSERT(2 <= elements_count, "unexpected number of elements");
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auto const& strategy = index::detail::get_strategy(parameters);
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// find the lowest low, highest high
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indexable_type const& indexable_0 = rtree::element_indexable(elements[0], translator);
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bounded_view_type const bounded_indexable_0(indexable_0, strategy);
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coordinate_type lowest_low = geometry::get<min_corner, DimensionIndex>(bounded_indexable_0);
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coordinate_type highest_high = geometry::get<max_corner, DimensionIndex>(bounded_indexable_0);
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// and the lowest high
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coordinate_type lowest_high = highest_high;
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size_t lowest_high_index = 0;
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for (size_t i = 1 ; i < elements_count ; ++i)
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{
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indexable_type const& indexable_i = rtree::element_indexable(elements[i], translator);
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bounded_view_type const bounded_indexable(indexable_i, strategy);
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coordinate_type min_coord = geometry::get<min_corner, DimensionIndex>(bounded_indexable);
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coordinate_type max_coord = geometry::get<max_corner, DimensionIndex>(bounded_indexable);
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if (max_coord < lowest_high)
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{
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lowest_high = max_coord;
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lowest_high_index = i;
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}
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if (min_coord < lowest_low)
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{
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lowest_low = min_coord;
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}
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if (highest_high < max_coord)
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{
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highest_high = max_coord;
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}
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}
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// find the highest low
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size_t highest_low_index = lowest_high_index == 0 ? 1 : 0;
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indexable_type const& indexable_hl = rtree::element_indexable(elements[highest_low_index], translator);
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bounded_view_type const bounded_indexable_hl(indexable_hl, strategy);
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coordinate_type highest_low = geometry::get<min_corner, DimensionIndex>(bounded_indexable_hl);
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for (size_t i = highest_low_index ; i < elements_count ; ++i)
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{
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indexable_type const& indexable = rtree::element_indexable(elements[i], translator);
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bounded_view_type const bounded_indexable(indexable, strategy);
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coordinate_type min_coord = geometry::get<min_corner, DimensionIndex>(bounded_indexable);
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if (highest_low < min_coord && i != lowest_high_index)
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{
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highest_low = min_coord;
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highest_low_index = i;
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}
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}
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coordinate_type const width = highest_high - lowest_low;
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// highest_low - lowest_high
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separation = difference<separation_type>(lowest_high, highest_low);
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// BOOST_GEOMETRY_INDEX_ASSERT(0 <= width);
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if (std::numeric_limits<coordinate_type>::epsilon() < width)
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{
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separation /= width;
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}
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seed1 = highest_low_index;
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seed2 = lowest_high_index;
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::boost::ignore_unused(parameters);
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}
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};
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// Version for points doesn't calculate normalized separation since it would always be equal to 1
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// It returns two seeds most distant to each other, separation is equal to distance
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template <typename Elements, typename Parameters, typename Translator, size_t DimensionIndex>
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struct find_greatest_normalized_separation<Elements, Parameters, Translator, point_tag, DimensionIndex>
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{
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typedef typename Elements::value_type element_type;
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typedef typename rtree::element_indexable_type<element_type, Translator>::type indexable_type;
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typedef typename coordinate_type<indexable_type>::type coordinate_type;
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typedef coordinate_type separation_type;
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static inline void apply(Elements const& elements,
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Parameters const& parameters,
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Translator const& translator,
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separation_type & separation,
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size_t & seed1,
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size_t & seed2)
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{
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const size_t elements_count = parameters.get_max_elements() + 1;
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BOOST_GEOMETRY_INDEX_ASSERT(elements.size() == elements_count, "unexpected number of elements");
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BOOST_GEOMETRY_INDEX_ASSERT(2 <= elements_count, "unexpected number of elements");
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// find the lowest low, highest high
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coordinate_type lowest = geometry::get<DimensionIndex>(rtree::element_indexable(elements[0], translator));
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coordinate_type highest = geometry::get<DimensionIndex>(rtree::element_indexable(elements[0], translator));
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size_t lowest_index = 0;
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size_t highest_index = 0;
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for ( size_t i = 1 ; i < elements_count ; ++i )
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{
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coordinate_type coord = geometry::get<DimensionIndex>(rtree::element_indexable(elements[i], translator));
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if ( coord < lowest )
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{
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lowest = coord;
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lowest_index = i;
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}
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if ( highest < coord )
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{
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highest = coord;
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highest_index = i;
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}
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}
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separation = highest - lowest;
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seed1 = lowest_index;
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seed2 = highest_index;
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if ( lowest_index == highest_index )
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seed2 = (lowest_index + 1) % elements_count; // % is just in case since if this is true lowest_index is 0
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::boost::ignore_unused(parameters);
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}
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};
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template <typename Elements, typename Parameters, typename Translator, size_t Dimension>
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struct pick_seeds_impl
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{
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BOOST_STATIC_ASSERT(0 < Dimension);
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typedef typename Elements::value_type element_type;
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typedef typename rtree::element_indexable_type<element_type, Translator>::type indexable_type;
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typedef find_greatest_normalized_separation<
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Elements, Parameters, Translator,
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typename tag<indexable_type>::type, Dimension - 1
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> find_norm_sep;
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typedef typename find_norm_sep::separation_type separation_type;
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static inline void apply(Elements const& elements,
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Parameters const& parameters,
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Translator const& tr,
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separation_type & separation,
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size_t & seed1,
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size_t & seed2)
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{
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pick_seeds_impl<Elements, Parameters, Translator, Dimension - 1>::apply(elements, parameters, tr, separation, seed1, seed2);
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separation_type current_separation;
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size_t s1, s2;
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find_norm_sep::apply(elements, parameters, tr, current_separation, s1, s2);
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// in the old implementation different operator was used: <= (y axis prefered)
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if ( separation < current_separation )
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{
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separation = current_separation;
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seed1 = s1;
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seed2 = s2;
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}
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}
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};
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template <typename Elements, typename Parameters, typename Translator>
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struct pick_seeds_impl<Elements, Parameters, Translator, 1>
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{
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typedef typename Elements::value_type element_type;
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typedef typename rtree::element_indexable_type<element_type, Translator>::type indexable_type;
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typedef typename coordinate_type<indexable_type>::type coordinate_type;
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typedef find_greatest_normalized_separation<
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Elements, Parameters, Translator,
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typename tag<indexable_type>::type, 0
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> find_norm_sep;
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typedef typename find_norm_sep::separation_type separation_type;
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static inline void apply(Elements const& elements,
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Parameters const& parameters,
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Translator const& tr,
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separation_type & separation,
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size_t & seed1,
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size_t & seed2)
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{
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find_norm_sep::apply(elements, parameters, tr, separation, seed1, seed2);
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}
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};
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// from void linear_pick_seeds(node_pointer const& n, unsigned int &seed1, unsigned int &seed2) const
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template <typename Elements, typename Parameters, typename Translator>
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inline void pick_seeds(Elements const& elements,
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Parameters const& parameters,
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Translator const& tr,
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size_t & seed1,
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size_t & seed2)
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{
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typedef typename Elements::value_type element_type;
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typedef typename rtree::element_indexable_type<element_type, Translator>::type indexable_type;
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typedef pick_seeds_impl
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<
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Elements, Parameters, Translator,
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geometry::dimension<indexable_type>::value
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> impl;
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typedef typename impl::separation_type separation_type;
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separation_type separation = 0;
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impl::apply(elements, parameters, tr, separation, seed1, seed2);
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}
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} // namespace linear
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// from void split_node(node_pointer const& n, node_pointer& n1, node_pointer& n2) const
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template <typename MembersHolder>
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struct redistribute_elements<MembersHolder, linear_tag>
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{
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typedef typename MembersHolder::box_type box_type;
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typedef typename MembersHolder::parameters_type parameters_type;
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typedef typename MembersHolder::translator_type translator_type;
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typedef typename MembersHolder::allocators_type allocators_type;
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typedef typename MembersHolder::node node;
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typedef typename MembersHolder::internal_node internal_node;
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typedef typename MembersHolder::leaf leaf;
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template <typename Node>
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static inline void apply(Node & n,
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Node & second_node,
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box_type & box1,
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box_type & box2,
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parameters_type const& parameters,
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translator_type const& translator,
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allocators_type & allocators)
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{
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typedef typename rtree::elements_type<Node>::type elements_type;
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typedef typename elements_type::value_type element_type;
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typedef typename rtree::element_indexable_type<element_type, translator_type>::type indexable_type;
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typedef typename index::detail::default_content_result<box_type>::type content_type;
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typename index::detail::strategy_type<parameters_type>::type const&
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strategy = index::detail::get_strategy(parameters);
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elements_type & elements1 = rtree::elements(n);
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elements_type & elements2 = rtree::elements(second_node);
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const size_t elements1_count = parameters.get_max_elements() + 1;
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BOOST_GEOMETRY_INDEX_ASSERT(elements1.size() == elements1_count, "unexpected number of elements");
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// copy original elements - use in-memory storage (std::allocator)
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// TODO: move if noexcept
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typedef typename rtree::container_from_elements_type<elements_type, element_type>::type
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container_type;
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container_type elements_copy(elements1.begin(), elements1.end()); // MAY THROW, STRONG (alloc, copy)
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// calculate initial seeds
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size_t seed1 = 0;
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size_t seed2 = 0;
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linear::pick_seeds(elements_copy, parameters, translator, seed1, seed2);
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// prepare nodes' elements containers
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elements1.clear();
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BOOST_GEOMETRY_INDEX_ASSERT(elements2.empty(), "unexpected container state");
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BOOST_TRY
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{
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// add seeds
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elements1.push_back(elements_copy[seed1]); // MAY THROW, STRONG (copy)
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elements2.push_back(elements_copy[seed2]); // MAY THROW, STRONG (alloc, copy)
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// calculate boxes
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detail::bounds(rtree::element_indexable(elements_copy[seed1], translator),
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box1, strategy);
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detail::bounds(rtree::element_indexable(elements_copy[seed2], translator),
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box2, strategy);
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// initialize areas
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content_type content1 = index::detail::content(box1);
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content_type content2 = index::detail::content(box2);
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BOOST_GEOMETRY_INDEX_ASSERT(2 <= elements1_count, "unexpected elements number");
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size_t remaining = elements1_count - 2;
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// redistribute the rest of the elements
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for ( size_t i = 0 ; i < elements1_count ; ++i )
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{
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if (i != seed1 && i != seed2)
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{
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element_type const& elem = elements_copy[i];
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indexable_type const& indexable = rtree::element_indexable(elem, translator);
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// if there is small number of elements left and the number of elements in node is lesser than min_elems
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// just insert them to this node
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if ( elements1.size() + remaining <= parameters.get_min_elements() )
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{
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elements1.push_back(elem); // MAY THROW, STRONG (copy)
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index::detail::expand(box1, indexable, strategy);
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content1 = index::detail::content(box1);
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}
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else if ( elements2.size() + remaining <= parameters.get_min_elements() )
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{
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elements2.push_back(elem); // MAY THROW, STRONG (alloc, copy)
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index::detail::expand(box2, indexable, strategy);
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content2 = index::detail::content(box2);
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}
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// choose better node and insert element
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else
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{
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// calculate enlarged boxes and areas
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box_type enlarged_box1(box1);
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box_type enlarged_box2(box2);
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index::detail::expand(enlarged_box1, indexable, strategy);
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index::detail::expand(enlarged_box2, indexable, strategy);
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content_type enlarged_content1 = index::detail::content(enlarged_box1);
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content_type enlarged_content2 = index::detail::content(enlarged_box2);
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content_type content_increase1 = enlarged_content1 - content1;
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content_type content_increase2 = enlarged_content2 - content2;
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// choose group which box content have to be enlarged least or has smaller content or has fewer elements
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if ( content_increase1 < content_increase2 ||
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( content_increase1 == content_increase2 &&
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( content1 < content2 ||
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( content1 == content2 && elements1.size() <= elements2.size() ) ) ) )
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{
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elements1.push_back(elem); // MAY THROW, STRONG (copy)
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box1 = enlarged_box1;
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content1 = enlarged_content1;
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}
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else
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{
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elements2.push_back(elem); // MAY THROW, STRONG (alloc, copy)
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box2 = enlarged_box2;
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content2 = enlarged_content2;
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}
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}
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BOOST_GEOMETRY_INDEX_ASSERT(0 < remaining, "unexpected value");
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--remaining;
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}
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}
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}
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BOOST_CATCH(...)
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{
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elements1.clear();
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elements2.clear();
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rtree::destroy_elements<MembersHolder>::apply(elements_copy, allocators);
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//elements_copy.clear();
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BOOST_RETHROW // RETHROW, BASIC
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}
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BOOST_CATCH_END
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}
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};
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}} // namespace detail::rtree
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}}} // namespace boost::geometry::index
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#endif // BOOST_GEOMETRY_INDEX_DETAIL_RTREE_LINEAR_REDISTRIBUTE_ELEMENTS_HPP
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