154 lines
4.3 KiB
C++
154 lines
4.3 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) 2020 Paul Ramsey <pramsey@cleverelephant.ca>
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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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#pragma once
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#include <geos/export.h>
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#include <vector>
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// Forward declarations
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namespace geos {
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namespace geom {
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class Coordinate;
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class CoordinateSequence;
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class Envelope;
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}
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}
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using geos::geom::Coordinate;
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using geos::geom::CoordinateSequence;
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using geos::geom::Envelope;
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namespace geos {
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namespace index {
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/**
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* A semi-static spatial index for points which occur
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* in a spatially-coherent sequence.
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* In particular, this is suitable for indexing the vertices
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* of a geos::geom::LineString or geos::geom::Polygon ring.
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*
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* The index is constructed in a batch fashion on a given sequence of coordinates.
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* Coordinates can be removed via the remove() method.
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*
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* Note that this index queries only the individual points
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* of the input coordinate sequence,
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* **not** any line segments which might be lie between them.
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*
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* @author Martin Davis
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*
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*/
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class GEOS_DLL VertexSequencePackedRtree {
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private:
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/**
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* Number of items/nodes in a parent node.
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* Determined empirically. Performance is not too sensitive to this.
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*/
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static constexpr std::size_t NODE_CAPACITY = 16;
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// Members
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const CoordinateSequence& items;
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std::vector<bool> removedItems;
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std::vector<std::size_t> levelOffset;
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std::size_t nodeCapacity = NODE_CAPACITY;
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std::vector<Envelope> bounds;
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// Methods
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void build();
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/**
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* Computes the level offsets.
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* This is the position in the <tt>bounds</tt> array of each level.
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*
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* The levelOffsets array includes a sentinel value of offset[0] = 0.
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* The top level is always of size 1,
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* and so also indicates the total number of bounds.
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*
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* @return the level offsets
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*/
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std::vector<std::size_t> computeLevelOffsets();
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static std::size_t ceilDivisor(std::size_t num, std::size_t denom);
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static std::size_t clampMax(std::size_t x, std::size_t max);
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std::size_t levelNodeCount(std::size_t numNodes);
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std::vector<Envelope> createBounds();
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void fillItemBounds(std::vector<Envelope>& bounds);
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void fillLevelBounds(std::size_t lvl, std::vector<Envelope>& bounds);
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static Envelope computeNodeEnvelope(const std::vector<Envelope>& bounds,
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std::size_t start, std::size_t end);
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static Envelope computeItemEnvelope(const CoordinateSequence& items,
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std::size_t start, std::size_t end);
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void queryNode(const Envelope& queryEnv,
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std::size_t level, std::size_t nodeIndex,
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std::vector<std::size_t>& result) const;
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void queryNodeRange(const Envelope& queryEnv,
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std::size_t level, std::size_t nodeStartIndex,
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std::vector<std::size_t>& result) const;
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void queryItemRange(const Envelope& queryEnv, std::size_t itemIndex,
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std::vector<std::size_t>& result) const;
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std::size_t levelSize(std::size_t level) const;
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bool isNodeEmpty(std::size_t level, std::size_t index);
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bool isItemsNodeEmpty(std::size_t nodeIndex);
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public:
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/**
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* Creates a new tree over the given sequence of coordinates.
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* The sequence should be spatially coherent to provide query performance.
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*
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* @param pts a sequence of points
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*/
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VertexSequencePackedRtree(const CoordinateSequence& pts);
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std::vector<Envelope> getBounds();
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/**
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* Removes the input item at the given index from the spatial index.
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*
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* @param index the index of the item in the input
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*/
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void remove(std::size_t index);
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/**
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* Queries the index to find all items which intersect an extent.
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* The query result is a list of the indices of input coordinates
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* which intersect the extent.
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*
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* @param queryEnv the query extent
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* @param result vector to fill with results
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*/
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void query(const Envelope& queryEnv, std::vector<std::size_t>& result) const;
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};
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} // namespace geos.index
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} // namespace geos
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