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geomfn.go
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geomfn.go
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// Copyright 2020 The Cockroach Authors.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0, included in the file
// licenses/APL.txt.
// Package geomfn contains functions that are used for geometry-based builtins.
package geomfn
import (
"github.com/ruiaylin/pgparser/types/geo"
"github.com/cockroachdb/errors"
"github.com/twpayne/go-geom"
)
// flattenGeometry flattens a geo.Geometry object.
func flattenGeometry(g *geo.Geometry, emptyBehavior geo.EmptyBehavior) ([]geom.T, error) {
f, err := g.AsGeomT()
if err != nil {
return nil, err
}
return flattenGeomT(f, emptyBehavior)
}
// flattenGeomT decomposes geom.T collections to individual geom.T components.
func flattenGeomT(g geom.T, emptyBehavior geo.EmptyBehavior) ([]geom.T, error) {
if g.Empty() {
switch emptyBehavior {
case geo.EmptyBehaviorOmit:
return nil, nil
case geo.EmptyBehaviorError:
return nil, geo.NewEmptyGeometryError()
default:
return nil, errors.Newf("programmer error: unknown behavior")
}
}
switch g := g.(type) {
case *geom.Point:
return []geom.T{g}, nil
case *geom.LineString:
return []geom.T{g}, nil
case *geom.Polygon:
return []geom.T{g}, nil
case *geom.MultiPoint:
ret := make([]geom.T, g.NumPoints())
for i := 0; i < g.NumPoints(); i++ {
ret[i] = g.Point(i)
}
return ret, nil
case *geom.MultiLineString:
ret := make([]geom.T, g.NumLineStrings())
for i := 0; i < g.NumLineStrings(); i++ {
ret[i] = g.LineString(i)
}
return ret, nil
case *geom.MultiPolygon:
ret := make([]geom.T, g.NumPolygons())
for i := 0; i < g.NumPolygons(); i++ {
ret[i] = g.Polygon(i)
}
return ret, nil
case *geom.GeometryCollection:
ret := make([]geom.T, 0, g.NumGeoms())
for _, subG := range g.Geoms() {
if subG.Empty() {
switch emptyBehavior {
case geo.EmptyBehaviorOmit:
continue
case geo.EmptyBehaviorError:
return nil, geo.NewEmptyGeometryError()
default:
return nil, errors.Newf("programmer error: unknown behavior")
}
}
ret = append(ret, subG)
}
return ret, nil
}
return nil, errors.Newf("unknown geom: %T", g)
}