tile38/vendor/github.com/tidwall/geojson/multilinestring.go
tidwall 6257ddba78 Faster point in polygon / GeoJSON updates
The big change is that the GeoJSON package has been completely
rewritten to fix a few of geometry calculation bugs, increase
performance, and to better follow the GeoJSON spec RFC 7946.

GeoJSON updates

- A LineString now requires at least two points.
- All json members, even foreign, now persist with the object.
- The bbox member persists too but is no longer used for geometry
  calculations. This is change in behavior. Previously Tile38 would
  treat the bbox as the object's physical rectangle.
- Corrections to geometry intersects and within calculations.

Faster spatial queries

- The performance of Point-in-polygon and object intersect operations
  are greatly improved for complex polygons and line strings. It went
  from O(n) to roughly O(log n).
- The same for all collection types with many children, including
  FeatureCollection, GeometryCollection, MultiPoint, MultiLineString,
  and MultiPolygon.

Codebase changes

- The pkg directory has been renamed to internal
- The GeoJSON internal package has been moved to a seperate repo at
  https://github.com/tidwall/geojson. It's now vendored.

Please look out for higher memory usage for datasets using complex
shapes. A complex shape is one that has 64 or more points. For these
shapes it's expected that there will be increase of least 54 bytes per
point.
2018-10-13 04:30:48 -07:00

85 lines
1.9 KiB
Go

package geojson
import (
"github.com/tidwall/geojson/geometry"
"github.com/tidwall/gjson"
)
// MultiLineString ...
type MultiLineString struct{ collection }
// NewMultiLineString ...
func NewMultiLineString(lines []*geometry.Line) *MultiLineString {
g := new(MultiLineString)
for _, line := range lines {
g.children = append(g.children, NewLineString(line))
}
g.parseInitRectIndex(DefaultParseOptions)
return g
}
// AppendJSON ...
func (g *MultiLineString) AppendJSON(dst []byte) []byte {
dst = append(dst, `{"type":"MultiLineString","coordinates":[`...)
for i, g := range g.children {
if i > 0 {
dst = append(dst, ',')
}
dst = append(dst,
gjson.GetBytes(g.AppendJSON(nil), "coordinates").String()...)
}
dst = append(dst, ']')
if g.extra != nil {
dst = g.extra.appendJSONExtra(dst)
}
dst = append(dst, '}')
return dst
}
// String ...
func (g *MultiLineString) String() string {
return string(g.AppendJSON(nil))
}
// JSON ...
func (g *MultiLineString) JSON() string {
return string(g.AppendJSON(nil))
}
func parseJSONMultiLineString(
keys *parseKeys, opts *ParseOptions,
) (Object, error) {
var g MultiLineString
var err error
if !keys.rCoordinates.Exists() {
return nil, errCoordinatesMissing
}
if !keys.rCoordinates.IsArray() {
return nil, errCoordinatesInvalid
}
var coords []geometry.Point
var ex *extra
keys.rCoordinates.ForEach(func(_, value gjson.Result) bool {
coords, ex, err = parseJSONLineStringCoords(keys, value, opts)
if err != nil {
return false
}
if len(coords) < 2 {
err = errCoordinatesInvalid
return false
}
line := geometry.NewLine(coords, opts.IndexGeometry)
g.children = append(g.children, &LineString{base: *line, extra: ex})
return true
})
if err != nil {
return nil, err
}
if err := parseBBoxAndExtras(&g.extra, keys, opts); err != nil {
return nil, err
}
g.parseInitRectIndex(opts)
return &g, nil
}