Add CLIP subcommand to INTERSECTS

pkg/collection/collection.go

@@ -497,9 +497,13 @@ func (c *Collection) Within(sparse uint8, obj geojson.Object, minLat, minLon, ma
 }
 
 // Intersects returns all object that are intersect an object or bounding box. Set obj to nil in order to use the bounding box.
-func (c *Collection) Intersects(sparse uint8, obj geojson.Object, minLat, minLon, maxLat, maxLon, lat, lon, meters, minZ, maxZ float64, iterator func(id string, obj geojson.Object, fields []float64) bool) bool {
+func (c *Collection) Intersects(
+	sparse uint8, obj geojson.Object,
+	minLat, minLon, maxLat, maxLon, lat, lon, meters, minZ, maxZ float64, doClip bool,
+	iterator func(id string, obj geojson.Object, fields []float64, clipBox geojson.BBox) bool) bool {
+
 	var keepon = true
-	var bbox geojson.BBox
+	var clipbox, bbox geojson.BBox
 	center := geojson.Position{X: lon, Y: lat, Z: 0}
 	if obj != nil {
 		bbox = obj.CalculatedBBox()
@@ -513,6 +517,9 @@ func (c *Collection) Intersects(sparse uint8, obj geojson.Object, minLat, minLon
 		bbox = geojson.BBoxesFromCenter(lat, lon, meters)
 	} else {
 		bbox = geojson.BBox{Min: geojson.Position{X: minLon, Y: minLat, Z: minZ}, Max: geojson.Position{X: maxLon, Y: maxLat, Z: maxZ}}
+		if doClip {
+			clipbox = bbox
+		}
 	}
 	var bboxes []geojson.BBox
 	if sparse > 0 {
@@ -531,7 +538,7 @@ func (c *Collection) Intersects(sparse uint8, obj geojson.Object, minLat, minLon
 			if obj != nil {
 				keepon = c.geoSearch(bbox, func(id string, o geojson.Object, fields []float64) bool {
 					if o.Intersects(obj) {
-						if iterator(id, o, fields) {
+						if iterator(id, o, fields, clipbox) {
 							return false
 						}
 					}
@@ -540,7 +547,7 @@ func (c *Collection) Intersects(sparse uint8, obj geojson.Object, minLat, minLon
 			} else if meters != -1 {
 				keepon = c.geoSearch(bbox, func(id string, o geojson.Object, fields []float64) bool {
 					if o.IntersectsCircle(center, meters) {
-						if iterator(id, o, fields) {
+						if iterator(id, o, fields, clipbox) {
 							return false
 						}
 					}
@@ -550,7 +557,7 @@ func (c *Collection) Intersects(sparse uint8, obj geojson.Object, minLat, minLon
 			if keepon {
 				keepon = c.geoSearch(bbox, func(id string, o geojson.Object, fields []float64) bool {
 					if o.IntersectsBBox(bbox) {
-						if iterator(id, o, fields) {
+						if iterator(id, o, fields, clipbox) {
 							return false
 						}
 					}
@@ -566,21 +573,21 @@ func (c *Collection) Intersects(sparse uint8, obj geojson.Object, minLat, minLon
 	if obj != nil {
 		return c.geoSearch(bbox, func(id string, o geojson.Object, fields []float64) bool {
 			if o.Intersects(obj) {
-				return iterator(id, o, fields)
+				return iterator(id, o, fields, clipbox)
 			}
 			return true
 		})
 	} else if meters != -1 {
 		return c.geoSearch(bbox, func(id string, o geojson.Object, fields []float64) bool {
 			if o.IntersectsCircle(center, meters) {
-				return iterator(id, o, fields)
+				return iterator(id, o, fields, clipbox)
 			}
 			return true
 		})
 	}
 	return c.geoSearch(bbox, func(id string, o geojson.Object, fields []float64) bool {
 		if o.IntersectsBBox(bbox) {
-			return iterator(id, o, fields)
+			return iterator(id, o, fields, clipbox)
 		}
 		return true
 	})

pkg/controller/scanner.go

@@ -65,6 +65,8 @@ type ScanWriterParams struct {
 	distance        float64
 	noLock          bool
 	ignoreGlobMatch bool
+	clip            bool
+	clipbox         geojson.BBox
 }
 
 func (c *Controller) newScanWriter(
@@ -342,6 +344,9 @@ func (sw *scanWriter) writeObject(opts ScanWriterParams) bool {
 	if sw.output == outputCount {
 		return sw.count < sw.limit
 	}
+	if opts.clip {
+		opts.o = opts.o.Clipped(opts.clipbox)
+	}
 	switch sw.msg.OutputType {
 	case server.JSON:
 		var wr bytes.Buffer

pkg/controller/search.go

@@ -100,6 +100,10 @@ func (c *Controller) cmdSearchArgs(cmd string, vs []resp.Value, types []string)
 			return
 		}
 
+		if s.clip {
+			err = errInvalidArgument("cannnot clip with point")
+		}
+
 		umeters := true
 		if vs, smeters, ok = tokenval(vs); !ok || smeters == "" {
 			umeters = false
@@ -134,6 +138,10 @@ func (c *Controller) cmdSearchArgs(cmd string, vs []resp.Value, types []string)
 			}
 		}
 	case "circle":
+		if s.clip {
+			err = errInvalidArgument("cannnot clip with circle")
+		}
+
 		var slat, slon, smeters string
 		if vs, slat, ok = tokenval(vs); !ok || slat == "" {
 			err = errInvalidNumberOfArguments
@@ -165,6 +173,10 @@ func (c *Controller) cmdSearchArgs(cmd string, vs []resp.Value, types []string)
 			return
 		}
 	case "object":
+		if s.clip {
+			err = errInvalidArgument("cannnot clip with object")
+		}
+
 		var obj string
 		if vs, obj, ok = tokenval(vs); !ok || obj == "" {
 			err = errInvalidNumberOfArguments
@@ -258,6 +270,9 @@ func (c *Controller) cmdSearchArgs(cmd string, vs []resp.Value, types []string)
 		}
 		s.minLat, s.minLon, s.maxLat, s.maxLon = bing.TileXYToBounds(x, y, z)
 	case "get":
+		if s.clip {
+			err = errInvalidArgument("cannnot clip with get")
+		}
 		var key, id string
 		if vs, key, ok = tokenval(vs); !ok || key == "" {
 			err = errInvalidNumberOfArguments
@@ -509,7 +524,8 @@ func (c *Controller) cmdWithinOrIntersects(cmd string, msg *server.Message) (res
 				s.minLat, s.minLon, s.maxLat, s.maxLon,
 				s.lat, s.lon, s.meters,
 				minZ, maxZ,
-				func(id string, o geojson.Object, fields []float64) bool {
+				s.clip,
+				func(id string, o geojson.Object, fields []float64, clipbox geojson.BBox) bool {
 					if c.hasExpired(s.key, id) {
 						return true
 					}
@@ -518,6 +534,8 @@ func (c *Controller) cmdWithinOrIntersects(cmd string, msg *server.Message) (res
 						o:      o,
 						fields: fields,
 						noLock: true,
+						clip:   s.clip,
+						clipbox: clipbox,
 					})
 				},
 			)

pkg/controller/token.go

@@ -245,6 +245,7 @@ type searchScanBaseTokens struct {
 	usparse   bool
 	sparse    uint8
 	desc      bool
+	clip      bool
 }
 
 func (c *Controller) parseSearchScanBaseTokens(cmd string, vs []resp.Value) (vsout []resp.Value, t searchScanBaseTokens, err error) {
@@ -551,6 +552,14 @@ func (c *Controller) parseSearchScanBaseTokens(cmd string, vs []resp.Value) (vso
 					return
 				}
 				continue
+			} else if (wtok[0] == 'C' || wtok[0] == 'c') && strings.ToLower(wtok) == "clip" {
+				vs = nvs
+				if t.clip {
+					err = errDuplicateArgument(strings.ToUpper(wtok))
+					return
+				}
+				t.clip = true
+				continue
 			}
 		}
 		break

pkg/core/commands.json

@@ -957,6 +957,12 @@
         "multiple": true,
         "variadic": true
       },
+      {
+        "command": "CLIP",
+        "name": [],
+        "type": [],
+        "optional": true
+      },
       {
         "command": "NOFIELDS",
         "name": [],

pkg/geojson/clip.go

@@ -0,0 +1,121 @@
+package geojson
+
+// Cohen-Sutherland Line Clipping
+// https://www.cs.helsinki.fi/group/goa/viewing/leikkaus/lineClip.html
+func ClipSegment(start, end Position, bbox BBox) (resStart, resEnd Position, rejected bool) {
+	startCode := getCode(bbox, start)
+	endCode := getCode(bbox, end)
+
+	if (startCode | endCode) == 0 {
+		// trivially accept
+		resStart, resEnd = start, end
+	} else if (startCode & endCode) != 0 {
+		// trivially reject
+		rejected = true
+	} else if startCode != 0 {
+		// start is outside. get new start.
+		newStart := intersect(bbox, startCode, start, end)
+		resStart, resEnd, rejected = ClipSegment(newStart, end, bbox)
+	} else {
+		// end is outside. get new end.
+		newEnd := intersect(bbox, endCode, start, end)
+		resStart, resEnd, rejected = ClipSegment(start, newEnd, bbox)
+	}
+
+	return
+}
+
+// Sutherland-Hodgman Polygon Clipping
+// https://www.cs.helsinki.fi/group/goa/viewing/leikkaus/intro2.html
+func ClipRing(ring[] Position, bbox BBox) (resRing []Position) {
+
+	if len(ring) < 4 {
+		// under 4 elements this is not a polygon ring!
+		return
+	}
+
+	var edge uint8
+	var inside, prevInside bool
+	var prev Position
+
+	for edge = 1; edge <= 8; edge *=2 {
+		prev = ring[len(ring) - 2]
+		prevInside = (getCode(bbox, prev) & edge) == 0
+
+		for _, p := range ring {
+
+			inside = (getCode(bbox, p) & edge) == 0
+
+			if prevInside && inside {
+				// Staying inside
+				resRing = append(resRing, p)
+			} else if prevInside && !inside {
+				// Leaving
+				resRing = append(resRing, intersect(bbox, edge, prev, p))
+			} else if !prevInside && inside {
+				// Entering
+				resRing = append(resRing, intersect(bbox, edge, prev, p))
+				resRing = append(resRing, p)
+			} else  {
+				// Staying outside
+			}
+
+			prev, prevInside = p, inside
+		}
+
+		if resRing[0] != resRing[len(resRing)-1] {
+			resRing = append(resRing, resRing[0])
+		}
+		ring, resRing = resRing, []Position{}
+	}
+
+	resRing = ring
+	return
+}
+
+
+func getCode(bbox BBox, point Position) (code uint8) {
+	code = 0
+
+	if point.X < bbox.Min.X {
+		code |= 1  // left
+	} else if point.X > bbox.Max.X {
+		code |= 2  // right
+	}
+
+	if point.Y < bbox.Min.Y {
+		code |= 4  // bottom
+	} else if point.Y > bbox.Max.Y {
+		code |= 8  // top
+	}
+
+	return
+}
+
+
+func intersect(bbox BBox, code uint8, start, end Position) (new Position) {
+	if (code & 8) != 0 {  // top
+		new = Position{
+			X: start.X + (end.X - start.X) * (bbox.Max.Y - start.Y) / (end.Y - start.Y),
+			Y: bbox.Max.Y,
+		}
+	} else if (code & 4) != 0 {  // bottom
+		new = Position{
+			X: start.X + (end.X - start.X) * (bbox.Min.Y - start.Y) / (end.Y - start.Y),
+			Y: bbox.Min.Y,
+		}
+	} else if (code & 2) != 0 {  //right
+		new = Position{
+			X: bbox.Max.X,
+			Y: start.Y + (end.Y - start.Y) * (bbox.Max.X - start.X) / (end.X - start.X),
+		}
+	} else if (code & 1) != 0 {  // left
+		new = Position{
+			X: bbox.Min.X,
+			Y: start.Y + (end.Y - start.Y) * (bbox.Min.X - start.X) / (end.X - start.X),
+		}
+	} else {  // should not call intersect with the zero code
+	}
+
+	return
+}

pkg/geojson/clip_test.go

@@ -0,0 +1,57 @@
+package geojson
+
+import "testing"
+
+func TestClipLineString(t *testing.T) {
+	ls, _ := fillLineString(
+		[]Position{
+			{X: 1, Y: 1},
+			{X: 2, Y: 2},
+			{X: 3, Y: 1},
+		}, nil, nil)
+	bbox := BBox{
+		Min: Position{X: 1.5, Y: 0.5},
+		Max: Position{X: 2.5, Y: 1.8},
+	}
+	clipped := ls.Clipped(bbox)
+	cl, ok := clipped.(MultiLineString)
+	if !ok {
+		t.Fatal("wrong type")
+	}
+	if len(cl.Coordinates) != 2 {
+		t.Fatal("result must have two parts in MultiString")
+	}
+}
+
+
+func TestClipPolygon(t *testing.T) {
+	outer := []Position{
+		{X: 2, Y: 2},
+		{X: 1, Y: 2},
+		{X: 1.5, Y: 1.5},
+		{X: 1, Y: 1},
+		{X: 2, Y: 1},
+		{X: 2, Y: 2},
+	}
+	inner := []Position{
+		{X: 1.9, Y: 1.9},
+		{X: 1.2, Y: 1.9},
+		{X: 1.45, Y: 1.65},
+		{X: 1.9, Y: 1.5},
+		{X: 1.9, Y: 1.9},
+
+	}
+	polygon, _ := fillPolygon([][]Position{outer, inner}, nil, nil)
+	bbox := BBox{
+		Min: Position{X: 1.3, Y: 1.3},
+		Max: Position{X: 1.4, Y: 2.15},
+	}
+	clipped := polygon.Clipped(bbox)
+	cp, ok := clipped.(Polygon)
+	if !ok {
+		t.Fatal("wrong type")
+	}
+	if len(cp.Coordinates) != 2 {
+		t.Fatal("result must have two parts in Polygon")
+	}
+}

pkg/geojson/feature.go

@@ -232,3 +232,14 @@ func (g Feature) IsBBoxDefined() bool {
 func (g Feature) IsGeometry() bool {
 	return true
 }
+
+// Clip returns the object obtained by clipping this object by a bbox.
+func (g Feature) Clipped(bbox BBox) Object {
+	clippedGeometry := g.Geometry.Clipped(bbox)
+
+	res := Feature{Geometry: clippedGeometry, idprops: g.idprops}
+	cbbox := clippedGeometry.CalculatedBBox()
+	res.BBox = &cbbox
+
+	return res
+}

pkg/geojson/featurecollection.go

@@ -248,3 +248,16 @@ func (g FeatureCollection) IsBBoxDefined() bool {
 func (g FeatureCollection) IsGeometry() bool {
 	return true
 }
+
+// Clip returns the object obtained by clipping this object by a bbox.
+func (g FeatureCollection) Clipped(bbox BBox) Object {
+	var new_features []Object
+	for _, feature := range g.Features {
+		new_features = append(new_features, feature.Clipped(bbox))
+	}
+
+	fc := FeatureCollection{Features: new_features}
+	cbbox := fc.CalculatedBBox()
+	fc.BBox = &cbbox
+	return fc
+}

pkg/geojson/geometrycollection.go

@@ -246,3 +246,16 @@ func (g GeometryCollection) IsBBoxDefined() bool {
 func (g GeometryCollection) IsGeometry() bool {
 	return true
 }
+
+// Clip returns the object of the same type as this object, clipped by a bbox.
+func (g GeometryCollection) Clipped(bbox BBox) Object {
+	var new_geometries []Object
+	for _, geometry := range g.Geometries {
+		new_geometries = append(new_geometries, geometry.Clipped(bbox))
+	}
+
+	gc := GeometryCollection{Geometries: new_geometries}
+	cbbox := gc.CalculatedBBox()
+	gc.BBox = &cbbox
+	return gc
+}

pkg/geojson/linestring.go

@@ -151,3 +151,31 @@ func (g LineString) IsBBoxDefined() bool {
 func (g LineString) IsGeometry() bool {
 	return true
 }
+
+// Clip returns the object obtained by clipping this object by a bbox.
+func (g LineString) Clipped(bbox BBox) Object {
+	var new_coordinates [][]Position
+	var clipedStart, clippedEnd Position
+	var rejected bool
+	var line []Position
+
+	for i := 0; i < len(g.Coordinates) - 1 ; i++ {
+		clipedStart, clippedEnd, rejected = ClipSegment(g.Coordinates[i], g.Coordinates[i + 1], bbox)
+		if rejected {
+			continue
+		}
+		if len(line) > 0 && line[len(line) - 1] != clipedStart {
+			new_coordinates = append(new_coordinates, line)
+			line = []Position{clipedStart}
+		} else if len(line) == 0 {
+			line = append(line, clipedStart)
+		}
+		line = append(line, clippedEnd)
+	}
+	if len(line) > 0 {
+		new_coordinates = append(new_coordinates, line)
+	}
+
+	res, _ := fillMultiLineString(new_coordinates, nil, nil)
+	return res
+}

pkg/geojson/multilinestring.go

@@ -209,3 +209,18 @@ func (g MultiLineString) IsBBoxDefined() bool {
 func (g MultiLineString) IsGeometry() bool {
 	return true
 }
+
+// Clip returns the object obtained by clipping this object by a bbox.
+func (g MultiLineString) Clipped(bbox BBox) Object {
+	var new_coordinates [][]Position
+
+	for ix := range g.Coordinates {
+		clippedMultiLineString, _ := g.getLineString(ix).Clipped(bbox).(MultiLineString)
+		for _, ls := range clippedMultiLineString.Coordinates {
+			new_coordinates = append(new_coordinates, ls)
+		}
+	}
+
+	res, _ := fillMultiLineString(new_coordinates, nil, nil)
+	return res
+}

pkg/geojson/multipoint.go

@@ -177,3 +177,18 @@ func (g MultiPoint) IsBBoxDefined() bool {
 func (g MultiPoint) IsGeometry() bool {
 	return true
 }
+
+// Clip returns the object obtained by clipping this object by a bbox.
+func (g MultiPoint) Clipped(bbox BBox) Object {
+	var new_coordinates []Position
+
+	for _, position := range g.Coordinates {
+		if poly.Point(position).InsideRect(rectBBox(bbox)) {
+			new_coordinates = append(new_coordinates, position)
+		}
+	}
+
+	res, _ := fillMultiPoint(new_coordinates, nil, nil)
+
+	return res
+}

pkg/geojson/multipolygon.go

@@ -213,3 +213,18 @@ func (g MultiPolygon) IsBBoxDefined() bool {
 func (g MultiPolygon) IsGeometry() bool {
 	return true
 }
+
+// Clip returns the object obtained by clipping this object by a bbox.
+func (g MultiPolygon) Clipped(bbox BBox) Object {
+	var new_coordinates [][][]Position
+
+	for _, polygon := range g.polygons {
+		clippedMultiPolygon, _ := polygon.Clipped(bbox).(MultiPolygon)
+		for _, pg := range clippedMultiPolygon.Coordinates {
+			new_coordinates = append(new_coordinates, pg)
+		}
+	}
+
+	res, _ := fillMultiPolygon(new_coordinates, nil, nil)
+	return res
+}

pkg/geojson/object.go

@@ -94,6 +94,8 @@ type Object interface {
 	IsBBoxDefined() bool
 	// IsGeometry return true if the object is a geojson geometry object. false if it something else.
 	IsGeometry() bool
+	// Clip returns the object obtained by clipping this object by a bbox.
+	Clipped(bbox BBox) Object
 }
 
 func positionBBox(i int, bbox BBox, ps []Position) (int, BBox) {

pkg/geojson/point.go

@@ -145,3 +145,13 @@ func (g Point) IsBBoxDefined() bool {
 func (g Point) IsGeometry() bool {
 	return true
 }
+
+// Clip returns the object obtained by clipping this object by a bbox.
+func (g Point) Clipped(bbox BBox) Object {
+	if g.IntersectsBBox(bbox) {
+		return g
+	}
+
+	res, _ := fillMultiPoint([]Position{}, nil, nil)
+	return res
+}

pkg/geojson/polygon.go

@@ -209,3 +209,15 @@ func (g Polygon) IsBBoxDefined() bool {
 func (g Polygon) IsGeometry() bool {
 	return true
 }
+
+// Clip returns the object obtained by clipping this object by a bbox.
+func (g Polygon) Clipped(bbox BBox) Object {
+	var new_coordinates [][]Position
+
+	for _, ring := range g.Coordinates {
+		new_coordinates = append(new_coordinates, ClipRing(ring, bbox))
+	}
+
+	res, _ := fillPolygon(new_coordinates, nil, nil)
+	return res
+}

pkg/geojson/simplepoint.go

@@ -127,3 +127,12 @@ func (g SimplePoint) IsBBoxDefined() bool {
 func (g SimplePoint) IsGeometry() bool {
 	return true
 }
+
+// Clip returns the object obtained by clipping this object by a bbox.
+func (g SimplePoint) Clipped(bbox BBox) Object {
+	if g.IntersectsBBox(bbox) {
+		return g
+	}
+	res, _ := fillMultiPoint([]Position{}, nil, nil)
+	return res
+}

pkg/geojson/string.go

@@ -73,6 +73,11 @@ func (s String) IsGeometry() bool {
 	return false
 }
 
+// Clip returns the object obtained by clipping this object by a bbox.
+func (s String) Clipped(bbox BBox) Object {
+	return s
+}
+
 // Bytes is the bytes representation of the object.
 func (s String) Bytes() []byte {
 	return []byte(s.String())