tree: implement casts between box2d and geometry

Release note (sql change): Implement the ability to cast between box2d
and geometry types.

pkg/geo/bbox.go

@@ -186,6 +186,27 @@ func (b *CartesianBoundingBox) Covers(o *CartesianBoundingBox) bool {
 		b.LoY <= o.HiY && o.HiY <= b.HiY
 }
 
+// ToGeomT converts a BoundingBox to a GeomT.
+func (b *CartesianBoundingBox) ToGeomT() geom.T {
+	if b.LoX == b.HiX && b.LoY == b.HiY {
+		return geom.NewPointFlat(geom.XY, []float64{b.LoX, b.LoY})
+	}
+	if b.LoX == b.HiX || b.LoY == b.HiY {
+		return geom.NewLineStringFlat(geom.XY, []float64{b.LoX, b.LoY, b.HiX, b.HiY})
+	}
+	return geom.NewPolygonFlat(
+		geom.XY,
+		[]float64{
+			b.LoX, b.LoY,
+			b.LoX, b.HiY,
+			b.HiX, b.HiY,
+			b.HiX, b.LoY,
+			b.LoX, b.LoY,
+		},
+		[]int{10},
+	)
+}
+
 // boundingBoxFromGeomT returns a bounding box from a given geom.T.
 // Returns nil if no bounding box was found.
 func boundingBoxFromGeomT(g geom.T, soType geopb.SpatialObjectType) (*geopb.BoundingBox, error) {

pkg/geo/geomfn/envelope.go

@@ -12,6 +12,7 @@ package geomfn
 
 import (
 	"github.com/cockroachdb/cockroach/pkg/geo"
+	"github.com/cockroachdb/errors"
 	"github.com/twpayne/go-geom"
 )
 
@@ -22,34 +23,15 @@ func Envelope(g *geo.Geometry) (*geo.Geometry, error) {
 	if g.Empty() {
 		return g, nil
 	}
-	bbox := g.CartesianBoundingBox()
-	if bbox.LoX == bbox.HiX && bbox.LoY == bbox.HiY {
-		return geo.NewGeometryFromGeomT(
-			geom.NewPointFlat(geom.XY, []float64{bbox.LoX, bbox.LoY}).SetSRID(int(g.SRID())),
-		)
+	t := g.CartesianBoundingBox().ToGeomT()
+	switch t := t.(type) {
+	case *geom.Point:
+		return geo.NewGeometryFromGeomT(t.SetSRID(int(g.SRID())))
+	case *geom.LineString:
+		return geo.NewGeometryFromGeomT(t.SetSRID(int(g.SRID())))
+	case *geom.Polygon:
+		return geo.NewGeometryFromGeomT(t.SetSRID(int(g.SRID())))
+	default:
+		return nil, errors.Newf("unknown geom type: %T", t)
 	}
-	if bbox.LoX == bbox.HiX || bbox.LoY == bbox.HiY {
-		return geo.NewGeometryFromGeomT(
-			geom.NewLineStringFlat(
-				geom.XY,
-				[]float64{
-					bbox.LoX, bbox.LoY,
-					bbox.HiX, bbox.HiY,
-				},
-			).SetSRID(int(g.SRID())),
-		)
-	}
-	return geo.NewGeometryFromGeomT(
-		geom.NewPolygonFlat(
-			geom.XY,
-			[]float64{
-				bbox.LoX, bbox.LoY,
-				bbox.LoX, bbox.HiY,
-				bbox.HiX, bbox.HiY,
-				bbox.HiX, bbox.LoY,
-				bbox.LoX, bbox.LoY,
-			},
-			[]int{10},
-		).SetSRID(int(g.SRID())),
-	)
 }

pkg/sql/logictest/testdata/logic_test/geospatial_bbox

@@ -135,3 +135,37 @@ NULL
 BOX(-1 -1,1 1)
 BOX(4 -5,4 -5)
 BOX(-1 -5,4 1)
+
+subtest cast_test
+
+query T
+SELECT
+  ST_AsEWKT(b::box2d::geometry)
+FROM ( VALUES
+  (NULL),
+  ('box(-1 -1,-1 -1)'),
+  ('box(1 3,20 3)'),
+  ('box(5.5 -10, 5.5 60)'),
+  ('box(-1 -2, 4 6)')
+) tbl(b)
+----
+NULL
+POINT (-1 -1)
+LINESTRING (1 3, 20 3)
+LINESTRING (5.5 -10, 5.5 60)
+POLYGON ((-1 -2, -1 6, 4 6, 4 -2, -1 -2))
+
+query T
+SELECT
+  g::geometry::box2d
+FROM ( VALUES
+  ('point empty'),
+  (null),
+  ('point(5 5)'),
+  ('linestring(4 5, 9 10)')
+) tbl(g)
+----
+NULL
+NULL
+BOX(5 5,5 5)
+BOX(4 5,9 10)

pkg/sql/sem/tree/casts.go

@@ -113,6 +113,8 @@ var validCasts = []castInfo{
 	{from: types.UnknownFamily, to: types.Box2DFamily, volatility: VolatilityImmutable},
 	{from: types.StringFamily, to: types.Box2DFamily, volatility: VolatilityImmutable},
 	{from: types.CollatedStringFamily, to: types.Box2DFamily, volatility: VolatilityImmutable},
+	{from: types.GeometryFamily, to: types.Box2DFamily, volatility: VolatilityImmutable},
+	{from: types.Box2DFamily, to: types.Box2DFamily, volatility: VolatilityImmutable},
 
 	// Casts to GeographyFamily.
 	{from: types.UnknownFamily, to: types.GeographyFamily, volatility: VolatilityImmutable},
@@ -125,6 +127,7 @@ var validCasts = []castInfo{
 
 	// Casts to GeometryFamily.
 	{from: types.UnknownFamily, to: types.GeometryFamily, volatility: VolatilityImmutable},
+	{from: types.Box2DFamily, to: types.GeometryFamily, volatility: VolatilityImmutable},
 	{from: types.BytesFamily, to: types.GeometryFamily, volatility: VolatilityImmutable},
 	{from: types.JsonFamily, to: types.GeometryFamily, volatility: VolatilityImmutable},
 	{from: types.StringFamily, to: types.GeometryFamily, volatility: VolatilityImmutable},
@@ -709,6 +712,13 @@ func PerformCast(ctx *EvalContext, d Datum, t *types.T) (Datum, error) {
 			return ParseDBox2D(string(*d))
 		case *DCollatedString:
 			return ParseDBox2D(d.Contents)
+		case *DBox2D:
+			return d, nil
+		case *DGeometry:
+			if d.Geometry.Empty() {
+				return DNull, nil
+			}
+			return NewDBox2D(d.CartesianBoundingBox()), nil
 		}
 
 	case types.GeographyFamily:
@@ -794,6 +804,12 @@ func PerformCast(ctx *EvalContext, d Datum, t *types.T) (Datum, error) {
 				return nil, err
 			}
 			return &DGeometry{g}, nil
+		case *DBox2D:
+			g, err := geo.NewGeometryFromGeomT(d.ToGeomT())
+			if err != nil {
+				return nil, err
+			}
+			return &DGeometry{g}, nil
 		case *DBytes:
 			g, err := geo.ParseGeometryFromEWKB(geopb.EWKB(*d))
 			if err != nil {