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318 lines
14 KiB
C++
318 lines
14 KiB
C++
// Boost.Geometry Index
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//
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// R-tree quadratic split algorithm implementation
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//
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// Copyright (c) 2011-2015 Adam Wulkiewicz, Lodz, Poland.
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//
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// This file was modified by Oracle on 2019.
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// Modifications copyright (c) 2019 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_QUADRATIC_REDISTRIBUTE_ELEMENTS_HPP
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#define BOOST_GEOMETRY_INDEX_DETAIL_RTREE_QUADRATIC_REDISTRIBUTE_ELEMENTS_HPP
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#include <algorithm>
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#include <boost/core/ignore_unused.hpp>
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#include <boost/geometry/index/detail/algorithms/content.hpp>
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#include <boost/geometry/index/detail/algorithms/union_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 quadratic {
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template <typename Box, 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 Box box_type;
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typedef typename index::detail::default_content_result<box_type>::type content_type;
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typedef typename index::detail::strategy_type<Parameters>::type strategy_type;
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typedef index::detail::bounded_view
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<
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indexable_type, box_type, strategy_type
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> bounded_indexable_view;
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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, "wrong number of elements");
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BOOST_GEOMETRY_INDEX_ASSERT(2 <= elements_count, "unexpected number of elements");
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strategy_type const& strategy = index::detail::get_strategy(parameters);
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content_type greatest_free_content = 0;
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seed1 = 0;
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seed2 = 1;
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for ( size_t i = 0 ; i < elements_count - 1 ; ++i )
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{
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for ( size_t j = i + 1 ; j < elements_count ; ++j )
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{
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indexable_type const& ind1 = rtree::element_indexable(elements[i], tr);
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indexable_type const& ind2 = rtree::element_indexable(elements[j], tr);
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box_type enlarged_box;
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index::detail::bounds(ind1, enlarged_box, strategy);
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index::detail::expand(enlarged_box, ind2, strategy);
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bounded_indexable_view bounded_ind1(ind1, strategy);
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bounded_indexable_view bounded_ind2(ind2, strategy);
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content_type free_content = ( index::detail::content(enlarged_box)
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- index::detail::content(bounded_ind1) )
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- index::detail::content(bounded_ind2);
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if ( greatest_free_content < free_content )
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{
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greatest_free_content = free_content;
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seed1 = i;
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seed2 = j;
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}
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}
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}
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::boost::ignore_unused(parameters);
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}
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} // namespace quadratic
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template <typename MembersHolder>
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struct redistribute_elements<MembersHolder, quadratic_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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typedef typename index::detail::default_content_result<box_type>::type content_type;
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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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elements_type & elements1 = rtree::elements(n);
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elements_type & elements2 = rtree::elements(second_node);
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BOOST_GEOMETRY_INDEX_ASSERT(elements1.size() == parameters.get_max_elements() + 1, "unexpected elements number");
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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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container_type elements_backup(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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quadratic::pick_seeds<box_type>(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(), "second node's elements container should be empty");
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BOOST_TRY
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{
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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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// 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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// remove seeds
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if (seed1 < seed2)
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{
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rtree::move_from_back(elements_copy, elements_copy.begin() + seed2); // MAY THROW, STRONG (copy)
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elements_copy.pop_back();
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rtree::move_from_back(elements_copy, elements_copy.begin() + seed1); // MAY THROW, STRONG (copy)
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elements_copy.pop_back();
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}
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else
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{
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rtree::move_from_back(elements_copy, elements_copy.begin() + seed1); // MAY THROW, STRONG (copy)
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elements_copy.pop_back();
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rtree::move_from_back(elements_copy, elements_copy.begin() + seed2); // MAY THROW, STRONG (copy)
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elements_copy.pop_back();
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}
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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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size_t remaining = elements_copy.size();
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// redistribute the rest of the elements
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while ( !elements_copy.empty() )
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{
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typename container_type::reverse_iterator el_it = elements_copy.rbegin();
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bool insert_into_group1 = false;
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size_t elements1_count = elements1.size();
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size_t elements2_count = elements2.size();
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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_count + remaining <= parameters.get_min_elements() )
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{
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insert_into_group1 = true;
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}
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else if ( elements2_count + remaining <= parameters.get_min_elements() )
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{
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insert_into_group1 = false;
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}
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// insert the best element
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else
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{
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// find element with minimum groups areas increses differences
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content_type content_increase1 = 0;
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content_type content_increase2 = 0;
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el_it = pick_next(elements_copy.rbegin(), elements_copy.rend(),
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box1, box2, content1, content2,
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translator, strategy,
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content_increase1, content_increase2);
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if ( content_increase1 < content_increase2 ||
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( content_increase1 == content_increase2 && ( content1 < content2 ||
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( content1 == content2 && elements1_count <= elements2_count ) )
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) )
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{
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insert_into_group1 = true;
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}
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else
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{
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insert_into_group1 = false;
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}
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}
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// move element to the choosen group
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element_type const& elem = *el_it;
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indexable_type const& indexable = rtree::element_indexable(elem, translator);
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if ( insert_into_group1 )
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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
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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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BOOST_GEOMETRY_INDEX_ASSERT(!elements_copy.empty(), "expected more elements");
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typename container_type::iterator el_it_base = el_it.base();
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rtree::move_from_back(elements_copy, --el_it_base); // MAY THROW, STRONG (copy)
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elements_copy.pop_back();
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BOOST_GEOMETRY_INDEX_ASSERT(0 < remaining, "expected more remaining elements");
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--remaining;
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}
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}
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BOOST_CATCH(...)
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{
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//elements_copy.clear();
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elements1.clear();
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elements2.clear();
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rtree::destroy_elements<MembersHolder>::apply(elements_backup, allocators);
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//elements_backup.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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// TODO: awulkiew - change following function to static member of the pick_next class?
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template <typename It>
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static inline It pick_next(It first, It last,
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box_type const& box1, box_type const& box2,
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content_type const& content1, content_type const& content2,
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translator_type const& translator,
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typename index::detail::strategy_type<parameters_type>::type const& strategy,
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content_type & out_content_increase1, content_type & out_content_increase2)
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{
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typedef typename boost::iterator_value<It>::type element_type;
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typedef typename rtree::element_indexable_type<element_type, translator_type>::type indexable_type;
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content_type greatest_content_incrase_diff = 0;
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It out_it = first;
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out_content_increase1 = 0;
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out_content_increase2 = 0;
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// find element with greatest difference between increased group's boxes areas
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for ( It el_it = first ; el_it != last ; ++el_it )
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{
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indexable_type const& indexable = rtree::element_indexable(*el_it, translator);
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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_incrase1 = (enlarged_content1 - content1);
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content_type content_incrase2 = (enlarged_content2 - content2);
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content_type content_incrase_diff = content_incrase1 < content_incrase2 ?
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content_incrase2 - content_incrase1 : content_incrase1 - content_incrase2;
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if ( greatest_content_incrase_diff < content_incrase_diff )
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{
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greatest_content_incrase_diff = content_incrase_diff;
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out_it = el_it;
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out_content_increase1 = content_incrase1;
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out_content_increase2 = content_incrase2;
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}
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}
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return out_it;
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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_QUADRATIC_REDISTRIBUTE_ELEMENTS_HPP
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