Merge pull request #1286 from sreekanth-cb/bounded_polygon

Support for bounded polygon query

Author: Sreekanth Sivasankaran

geo/geo.go

@@ -37,6 +37,12 @@ var geoTolerance = 1E-6
 var lonScale = float64((uint64(0x1)<<GeoBits)-1) / 360.0
 var latScale = float64((uint64(0x1)<<GeoBits)-1) / 180.0
 
+// Point represents a geo point.
+type Point struct {
+	Lon float64
+	Lat float64
+}
+
 // MortonHash computes the morton hash value for the provided geo point
 // This point is ordered as lon, lat.
 func MortonHash(lon, lat float64) uint64 {
@@ -168,3 +174,35 @@ func checkLongitude(longitude float64) error {
 	}
 	return nil
 }
+
+func BoundingRectangleForPolygon(polygon []Point) (
+	float64, float64, float64, float64, error) {
+	err := checkLongitude(polygon[0].Lon)
+	if err != nil {
+		return 0, 0, 0, 0, err
+	}
+	err = checkLatitude(polygon[0].Lat)
+	if err != nil {
+		return 0, 0, 0, 0, err
+	}
+	maxY, minY := polygon[0].Lat, polygon[0].Lat
+	maxX, minX := polygon[0].Lon, polygon[0].Lon
+	for i := 1; i < len(polygon); i++ {
+		err := checkLongitude(polygon[i].Lon)
+		if err != nil {
+			return 0, 0, 0, 0, err
+		}
+		err = checkLatitude(polygon[i].Lat)
+		if err != nil {
+			return 0, 0, 0, 0, err
+		}
+
+		maxY = math.Max(maxY, polygon[i].Lat)
+		minY = math.Min(minY, polygon[i].Lat)
+
+		maxX = math.Max(maxX, polygon[i].Lon)
+		minX = math.Min(minX, polygon[i].Lon)
+	}
+
+	return minX, maxY, maxX, minY, nil
+}

search/query/geo_boundingpolygon.go

@@ -0,0 +1,94 @@
+//  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 query
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/blevesearch/bleve/geo"
+	"github.com/blevesearch/bleve/index"
+	"github.com/blevesearch/bleve/mapping"
+	"github.com/blevesearch/bleve/search"
+	"github.com/blevesearch/bleve/search/searcher"
+)
+
+type GeoBoundingPolygonQuery struct {
+	Points   []geo.Point `json:"polygon_points"`
+	FieldVal string      `json:"field,omitempty"`
+	BoostVal *Boost      `json:"boost,omitempty"`
+}
+
+func NewGeoBoundingPolygonQuery(points []geo.Point) *GeoBoundingPolygonQuery {
+	return &GeoBoundingPolygonQuery{
+		Points: points}
+}
+
+func (q *GeoBoundingPolygonQuery) SetBoost(b float64) {
+	boost := Boost(b)
+	q.BoostVal = &boost
+}
+
+func (q *GeoBoundingPolygonQuery) Boost() float64 {
+	return q.BoostVal.Value()
+}
+
+func (q *GeoBoundingPolygonQuery) SetField(f string) {
+	q.FieldVal = f
+}
+
+func (q *GeoBoundingPolygonQuery) Field() string {
+	return q.FieldVal
+}
+
+func (q *GeoBoundingPolygonQuery) Searcher(i index.IndexReader,
+	m mapping.IndexMapping, options search.SearcherOptions) (search.Searcher, error) {
+	field := q.FieldVal
+	if q.FieldVal == "" {
+		field = m.DefaultSearchField()
+	}
+
+	return searcher.NewGeoBoundedPolygonSearcher(i, q.Points, field, q.BoostVal.Value(), options)
+}
+
+func (q *GeoBoundingPolygonQuery) Validate() error {
+	return nil
+}
+
+func (q *GeoBoundingPolygonQuery) UnmarshalJSON(data []byte) error {
+	tmp := struct {
+		Points   []interface{} `json:"polygon_points"`
+		FieldVal string        `json:"field,omitempty"`
+		BoostVal *Boost        `json:"boost,omitempty"`
+	}{}
+	err := json.Unmarshal(data, &tmp)
+	if err != nil {
+		return err
+	}
+
+	q.Points = make([]geo.Point, 0, len(tmp.Points))
+	for _, i := range tmp.Points {
+		// now use our generic point parsing code from the geo package
+		lon, lat, found := geo.ExtractGeoPoint(i)
+		if !found {
+			return fmt.Errorf("geo polygon point: %v is not in a valid format", i)
+		}
+		q.Points = append(q.Points, geo.Point{Lon: lon, Lat: lat})
+	}
+
+	q.FieldVal = tmp.FieldVal
+	q.BoostVal = tmp.BoostVal
+	return nil
+}

search/query/query.go

@@ -273,6 +273,15 @@ func ParseQuery(input []byte) (Query, error) {
 		}
 		return &rv, nil
 	}
+	_, hasPoints := tmp["polygon_points"]
+	if hasPoints {
+		var rv GeoBoundingPolygonQuery
+		err := json.Unmarshal(input, &rv)
+		if err != nil {
+			return nil, err
+		}
+		return &rv, nil
+	}
 	return nil, fmt.Errorf("unknown query type")
 }
 

search/searcher/search_geopointdistance.go

@@ -34,7 +34,7 @@ func NewGeoPointDistanceSearcher(indexReader index.IndexReader, centerLon,
 	// build a searcher for the box
 	boxSearcher, err := boxSearcher(indexReader,
 		topLeftLon, topLeftLat, bottomRightLon, bottomRightLat,
-		field, boost, options)
+		field, boost, options, false)
 	if err != nil {
 		return nil, err
 	}
@@ -54,19 +54,20 @@ func NewGeoPointDistanceSearcher(indexReader index.IndexReader, centerLon,
 // two boxes joined through a disjunction searcher
 func boxSearcher(indexReader index.IndexReader,
 	topLeftLon, topLeftLat, bottomRightLon, bottomRightLat float64,
-	field string, boost float64, options search.SearcherOptions) (
+	field string, boost float64, options search.SearcherOptions, checkBoundaries bool) (
 	search.Searcher, error) {
 	if bottomRightLon < topLeftLon {
 		// cross date line, rewrite as two parts
 
 		leftSearcher, err := NewGeoBoundingBoxSearcher(indexReader,
 			-180, bottomRightLat, bottomRightLon, topLeftLat,
-			field, boost, options, false)
+			field, boost, options, checkBoundaries)
 		if err != nil {
 			return nil, err
 		}
 		rightSearcher, err := NewGeoBoundingBoxSearcher(indexReader,
-			topLeftLon, bottomRightLat, 180, topLeftLat, field, boost, options, false)
+			topLeftLon, bottomRightLat, 180, topLeftLat, field, boost, options,
+			checkBoundaries)
 		if err != nil {
 			_ = leftSearcher.Close()
 			return nil, err
@@ -85,7 +86,7 @@ func boxSearcher(indexReader index.IndexReader,
 	// build geoboundinggox searcher for that bounding box
 	boxSearcher, err := NewGeoBoundingBoxSearcher(indexReader,
 		topLeftLon, bottomRightLat, bottomRightLon, topLeftLat, field, boost,
-		options, false)
+		options, checkBoundaries)
 	if err != nil {
 		return nil, err
 	}

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
+	}
+}