Adding upstream version 2.5.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

search/searcher/search_geopolygon.go

@@ -0,0 +1,149 @@
+//  Copyright (c) 2019 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package searcher
+
+import (
+	"context"
+	"fmt"
+	"math"
+
+	"github.com/blevesearch/bleve/v2/geo"
+	"github.com/blevesearch/bleve/v2/numeric"
+	"github.com/blevesearch/bleve/v2/search"
+	index "github.com/blevesearch/bleve_index_api"
+)
+
+func NewGeoBoundedPolygonSearcher(ctx context.Context, indexReader index.IndexReader,
+	coordinates []geo.Point, field string, boost float64,
+	options search.SearcherOptions) (search.Searcher, error) {
+	if len(coordinates) < 3 {
+		return nil, fmt.Errorf("Too few points specified for the polygon boundary")
+	}
+
+	var rectSearcher search.Searcher
+	if sr, ok := indexReader.(index.SpatialIndexPlugin); ok {
+		tp, err := sr.GetSpatialAnalyzerPlugin("s2")
+		if err == nil {
+			terms := tp.GetQueryTokens(geo.NewBoundedPolygon(coordinates))
+			rectSearcher, err = NewMultiTermSearcher(ctx, indexReader, terms,
+				field, boost, options, false)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	// indexes without the spatial plugin override would get
+	// initialized here.
+	if rectSearcher == nil {
+		// compute the bounding box enclosing the polygon
+		topLeftLon, topLeftLat, bottomRightLon, bottomRightLat, err :=
+			geo.BoundingRectangleForPolygon(coordinates)
+		if err != nil {
+			return nil, err
+		}
+
+		// build a searcher for the bounding box on the polygon
+		rectSearcher, err = boxSearcher(ctx, indexReader,
+			topLeftLon, topLeftLat, bottomRightLon, bottomRightLat,
+			field, boost, options, true)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	dvReader, err := indexReader.DocValueReader([]string{field})
+	if err != nil {
+		return nil, err
+	}
+
+	// wrap it in a filtering searcher that checks for the polygon inclusivity
+	return NewFilteringSearcher(ctx, rectSearcher,
+		buildPolygonFilter(ctx, dvReader, field, coordinates)), nil
+}
+
+const float64EqualityThreshold = 1e-6
+
+func almostEqual(a, b float64) bool {
+	return math.Abs(a-b) <= float64EqualityThreshold
+}
+
+// buildPolygonFilter returns true if the point lies inside the
+// polygon. It is based on the ray-casting technique as referred
+// here: https://wrf.ecse.rpi.edu/nikola/pubdetails/pnpoly.html
+func buildPolygonFilter(ctx context.Context, dvReader index.DocValueReader, field string,
+	coordinates []geo.Point) FilterFunc {
+	return func(d *search.DocumentMatch) bool {
+		// check geo matches against all numeric type terms indexed
+		var lons, lats []float64
+		var found bool
+
+		err := dvReader.VisitDocValues(d.IndexInternalID, func(field string, term []byte) {
+			// only consider the values which are shifted 0
+			prefixCoded := numeric.PrefixCoded(term)
+			shift, err := prefixCoded.Shift()
+			if err == nil && shift == 0 {
+				i64, err := prefixCoded.Int64()
+				if err == nil {
+					lons = append(lons, geo.MortonUnhashLon(uint64(i64)))
+					lats = append(lats, geo.MortonUnhashLat(uint64(i64)))
+					found = true
+				}
+			}
+		})
+
+		// Note: this approach works for points which are strictly inside
+		// the polygon. ie it might fail for certain points on the polygon boundaries.
+		if err == nil && found {
+			bytes := dvReader.BytesRead()
+			if bytes > 0 {
+				reportIOStats(ctx, bytes)
+				search.RecordSearchCost(ctx, search.AddM, bytes)
+			}
+			nVertices := len(coordinates)
+			if len(coordinates) < 3 {
+				return false
+			}
+			rayIntersectsSegment := func(point, a, b geo.Point) bool {
+				return (a.Lat > point.Lat) != (b.Lat > point.Lat) &&
+					point.Lon < (b.Lon-a.Lon)*(point.Lat-a.Lat)/(b.Lat-a.Lat)+a.Lon
+			}
+
+			for i := range lons {
+				pt := geo.Point{Lon: lons[i], Lat: lats[i]}
+				inside := rayIntersectsSegment(pt, coordinates[len(coordinates)-1], coordinates[0])
+				// check for a direct vertex match
+				if almostEqual(coordinates[0].Lat, lats[i]) &&
+					almostEqual(coordinates[0].Lon, lons[i]) {
+					return true
+				}
+
+				for j := 1; j < nVertices; j++ {
+					if almostEqual(coordinates[j].Lat, lats[i]) &&
+						almostEqual(coordinates[j].Lon, lons[i]) {
+						return true
+					}
+					if rayIntersectsSegment(pt, coordinates[j-1], coordinates[j]) {
+						inside = !inside
+					}
+				}
+				if inside {
+					return true
+				}
+			}
+		}
+		return false
+	}
+}