Upgrade blevesearch to v0.8.1 (#9177)

For #1441

a91b427b59

vendor/github.com/blevesearch/bleve/search/searcher/search_geopolygon.go

@@ -0,0 +1,110 @@
+//  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 (
+	"github.com/blevesearch/bleve/geo"
+	"github.com/blevesearch/bleve/index"
+	"github.com/blevesearch/bleve/numeric"
+	"github.com/blevesearch/bleve/search"
+	"math"
+)
+
+func NewGeoBoundedPolygonSearcher(indexReader index.IndexReader,
+	polygon []geo.Point, field string, boost float64,
+	options search.SearcherOptions) (search.Searcher, error) {
+
+	// compute the bounding box enclosing the polygon
+	topLeftLon, topLeftLat, bottomRightLon, bottomRightLat, err :=
+		geo.BoundingRectangleForPolygon(polygon)
+	if err != nil {
+		return nil, err
+	}
+
+	// build a searcher for the bounding box on the polygon
+	boxSearcher, err := boxSearcher(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(boxSearcher,
+		buildPolygonFilter(dvReader, field, polygon)), 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(dvReader index.DocValueReader, field string,
+	polygon []geo.Point) FilterFunc {
+	return func(d *search.DocumentMatch) bool {
+		var lon, lat 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 {
+					lon = geo.MortonUnhashLon(uint64(i64))
+					lat = 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 {
+			nVertices := len(polygon)
+			var inside bool
+			// check for a direct vertex match
+			if almostEqual(polygon[0].Lat, lat) &&
+				almostEqual(polygon[0].Lon, lon) {
+				return true
+			}
+
+			for i := 1; i < nVertices; i++ {
+				if almostEqual(polygon[i].Lat, lat) &&
+					almostEqual(polygon[i].Lon, lon) {
+					return true
+				}
+				if (polygon[i].Lat > lat) != (polygon[i-1].Lat > lat) &&
+					lon < (polygon[i-1].Lon-polygon[i].Lon)*(lat-polygon[i].Lat)/
+						(polygon[i-1].Lat-polygon[i].Lat)+polygon[i].Lon {
+					inside = !inside
+				}
+			}
+			return inside
+
+		}
+		return false
+	}
+}