mirror of https://github.com/go-gitea/gitea.git
127 lines
3.8 KiB
Go
127 lines
3.8 KiB
Go
// Copyright (c) 2019 Couchbase, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package searcher
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import (
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"fmt"
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"github.com/blevesearch/bleve/geo"
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"github.com/blevesearch/bleve/index"
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"github.com/blevesearch/bleve/numeric"
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"github.com/blevesearch/bleve/search"
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"math"
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)
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func NewGeoBoundedPolygonSearcher(indexReader index.IndexReader,
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polygon []geo.Point, field string, boost float64,
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options search.SearcherOptions) (search.Searcher, error) {
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if len(polygon) < 3 {
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return nil, fmt.Errorf("Too few points specified for the polygon boundary")
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}
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// compute the bounding box enclosing the polygon
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topLeftLon, topLeftLat, bottomRightLon, bottomRightLat, err :=
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geo.BoundingRectangleForPolygon(polygon)
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if err != nil {
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return nil, err
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}
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// build a searcher for the bounding box on the polygon
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boxSearcher, err := boxSearcher(indexReader,
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topLeftLon, topLeftLat, bottomRightLon, bottomRightLat,
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field, boost, options, true)
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if err != nil {
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return nil, err
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}
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dvReader, err := indexReader.DocValueReader([]string{field})
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if err != nil {
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return nil, err
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}
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// wrap it in a filtering searcher that checks for the polygon inclusivity
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return NewFilteringSearcher(boxSearcher,
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buildPolygonFilter(dvReader, field, polygon)), nil
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}
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const float64EqualityThreshold = 1e-6
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func almostEqual(a, b float64) bool {
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return math.Abs(a-b) <= float64EqualityThreshold
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}
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// buildPolygonFilter returns true if the point lies inside the
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// polygon. It is based on the ray-casting technique as referred
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// here: https://wrf.ecse.rpi.edu/nikola/pubdetails/pnpoly.html
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func buildPolygonFilter(dvReader index.DocValueReader, field string,
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polygon []geo.Point) FilterFunc {
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return func(d *search.DocumentMatch) bool {
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// check geo matches against all numeric type terms indexed
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var lons, lats []float64
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var found bool
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err := dvReader.VisitDocValues(d.IndexInternalID, func(field string, term []byte) {
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// only consider the values which are shifted 0
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prefixCoded := numeric.PrefixCoded(term)
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shift, err := prefixCoded.Shift()
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if err == nil && shift == 0 {
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i64, err := prefixCoded.Int64()
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if err == nil {
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lons = append(lons, geo.MortonUnhashLon(uint64(i64)))
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lats = append(lats, geo.MortonUnhashLat(uint64(i64)))
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found = true
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}
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}
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})
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// Note: this approach works for points which are strictly inside
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// the polygon. ie it might fail for certain points on the polygon boundaries.
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if err == nil && found {
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nVertices := len(polygon)
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if len(polygon) < 3 {
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return false
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}
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rayIntersectsSegment := func(point, a, b geo.Point) bool {
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return (a.Lat > point.Lat) != (b.Lat > point.Lat) &&
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point.Lon < (b.Lon-a.Lon)*(point.Lat-a.Lat)/(b.Lat-a.Lat)+a.Lon
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}
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for i := range lons {
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pt := geo.Point{Lon: lons[i], Lat: lats[i]}
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inside := rayIntersectsSegment(pt, polygon[len(polygon)-1], polygon[0])
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// check for a direct vertex match
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if almostEqual(polygon[0].Lat, lats[i]) &&
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almostEqual(polygon[0].Lon, lons[i]) {
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return true
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}
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for j := 1; j < nVertices; j++ {
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if almostEqual(polygon[j].Lat, lats[i]) &&
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almostEqual(polygon[j].Lon, lons[i]) {
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return true
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}
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if rayIntersectsSegment(pt, polygon[j-1], polygon[j]) {
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inside = !inside
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}
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}
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if inside {
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return true
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}
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}
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}
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return false
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}
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}
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