Refactor ring validation in Polygon's Validate method

geom/type_polygon.go

@@ -63,23 +63,11 @@ func (p Polygon) Validate() error {
 	}
 
 	for i, r := range p.rings {
-		if err := r.Validate(); err != nil {
+		if err := validateRing(r); err != nil {
 			return wrap(err, "validating ring at index %d", i)
 		}
 	}
 
-	for _, r := range p.rings {
-		if r.IsEmpty() {
-			return violateRingEmpty.err()
-		}
-		if !r.IsClosed() {
-			return violateRingClosed.errAtXY(r.Coordinates().GetXY(0))
-		}
-		if !r.IsSimple() {
-			return violateRingSimple.errAtXY(r.Coordinates().GetXY(0))
-		}
-	}
-
 	// Data structures used to track connectedness.
 	nextInterVert := len(p.rings)
 	interVerts := make(map[XY]int)
@@ -165,6 +153,22 @@ func (p Polygon) Validate() error {
 	return nil
 }
 
+func validateRing(r LineString) error {
+	if err := r.Validate(); err != nil {
+		return err
+	}
+	if r.IsEmpty() {
+		return violateRingEmpty.err()
+	}
+	if !r.IsClosed() {
+		return violateRingClosed.errAtXY(r.Coordinates().GetXY(0))
+	}
+	if !r.IsSimple() {
+		return violateRingSimple.errAtXY(r.Coordinates().GetXY(0))
+	}
+	return nil
+}
+
 // Type returns the GeometryType for a Polygon
 func (p Polygon) Type() GeometryType {
 	return TypePolygon