123 lines
3.6 KiB
C++
123 lines
3.6 KiB
C++
/**********************************************************************
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*
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* GEOS - Geometry Engine Open Source
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* http://geos.osgeo.org
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*
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* Copyright (C) 2016 Daniel Baston
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*
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* This is free software; you can redistribute and/or modify it under
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* the terms of the GNU Lesser General Public Licence as published
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* by the Free Software Foundation.
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* See the COPYING file for more information.
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*
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**********************************************************************
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*
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* Last port: index/strtree/BoundablePair.java (JTS-1.14)
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*
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**********************************************************************/
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#pragma once
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#include <geos/index/strtree/Boundable.h>
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#include <geos/index/strtree/ItemDistance.h>
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#include <queue>
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namespace geos {
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namespace index {
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namespace strtree {
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/**
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* @brief A pair of [Boundables](@ref Boundable), whose
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* leaf items support a distance metric between them.
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*
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* Used to compute the distance between the members,
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* and to expand a member relative to the other
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* in order to produce new branches of the
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* Branch-and-Bound evaluation tree.
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* Provides an ordering based on the distance between the members,
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* which allows building a priority queue by minimum distance.
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*
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* @author Martin Davis
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*
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*/
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class BoundablePair {
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private:
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const Boundable* boundable1;
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const Boundable* boundable2;
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ItemDistance* itemDistance;
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double mDistance;
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public:
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struct BoundablePairQueueCompare {
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bool
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operator()(const BoundablePair* a, const BoundablePair* b)
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{
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return a->getDistance() > b->getDistance();
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}
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};
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typedef std::priority_queue<BoundablePair*, std::vector<BoundablePair*>, BoundablePairQueueCompare> BoundablePairQueue;
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BoundablePair(const Boundable* boundable1, const Boundable* boundable2, ItemDistance* itemDistance);
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/**
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* Gets one of the member {@link Boundable}s in the pair
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* (indexed by [0, 1]).
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*
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* @param i the index of the member to return (0 or 1)
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* @return the chosen member
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*/
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const Boundable* getBoundable(int i) const;
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/** \brief
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* Computes the distance between the {@link Boundable}s in this pair.
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* The boundables are either composites or leaves.
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*
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* If either is composite, the distance is computed as the minimum distance
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* between the bounds.
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* If both are leaves, the distance is computed by
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* ItemDistance::distance(const ItemBoundable* item1, const ItemBoundable* item2).
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*
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* @return the distance between the items
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*/
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double distance() const;
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/** \brief
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* Gets the minimum possible distance between the Boundables in this pair.
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*
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* If the members are both items, this will be the
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* exact distance between them.
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* Otherwise, this distance will be a lower bound on
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* the distances between the items in the members.
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*
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* @return the exact or lower bound distance for this pair
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*/
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double getDistance() const;
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/**
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* Tests if both elements of the pair are leaf nodes
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*
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* @return true if both pair elements are leaf nodes
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*/
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bool isLeaves() const;
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/** \brief
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* Computes the maximum distance between any
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* two items in the pair of nodes.
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*
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* @return the maximum distance between items in the pair
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*/
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double maximumDistance();
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static bool isComposite(const Boundable* item);
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static double area(const Boundable* b);
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void expandToQueue(BoundablePairQueue&, double minDistance);
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void expand(const Boundable* bndComposite, const Boundable* bndOther, bool isFlipped, BoundablePairQueue& priQ,
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double minDistance);
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};
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}
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}
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}
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