fix decoding encoreding

encoding/polylines/decoding.go

@@ -6,6 +6,62 @@ import (
 	"github.com/paulmach/orb"
 )
 
+// // Decode decodes coordinates to the "Encoded Polyline Algorithm Format"
+// // More info: https://developers.google.com/maps/documentation/utilities/polylinealgorithm
+// // polyline: polyline string in "Encoded Polyline Algorithm Format"
+// // precision: usually 5 or 6; Google's original algorithm uses 5 digits of decimal precision,
+// // which is accurate to about a meter. A precision of 6 gives you an accuracy of about 10cm
+// // more info: https://mapzen.com/blog/polyline-precision/
+// func Decode(polyline string, precision uint32) orb.LineString {
+
+// 	group := ""
+// 	coordinates := []float64{}
+
+// 	for _, letter := range polyline {
+// 		group += string(letter)
+
+// 		if (int32(letter)-63)&0x20 == 0 {
+// 			coordinates = append(coordinates, decodeElement(group, precision))
+// 			group = ""
+// 		}
+// 	}
+
+// 	points := orb.LineString{}
+// 	for i := 1; i < len(coordinates); i += 2 {
+// 		points = append(points, orb.Point{round(coordinates[i], precision), round(coordinates[i-1], precision)})
+// 	}
+
+// 	for i := range points {
+// 		if i > 0 {
+// 			points[i][1] = round(points[i-1].Lat()+points[i].Lat(), precision)
+// 			points[i][0] = round(points[i-1].Lon()+points[i].Lon(), precision)
+// 		}
+// 	}
+
+// 	return points
+// }
+
+// // Decode5 is a short call for Decode with precision set to 5
+// // Accuracy is about one meter
+// func Decode5(polyline string) orb.LineString {
+// 	return Decode(polyline, 5)
+// }
+
+// // Decode6 is a short call for Decode with precision set to 6
+// // Accuracy is about ten centimeters
+// func Decode6(polyline string) orb.LineString {
+// 	return Decode(polyline, 6)
+// }
+
+// // decodeElement decodes an coordinate element (i.e. latitude or longitude)
+// // from the "Encoded Polyline Algorithm Format"
+// func decodeElement(group string, precision uint32) float64 {
+
+// 	var c chunks
+// 	c.ParseLine(group)
+// 	return c.Coordinate(precision)
+// }
+
 func Decode(encoded *string, precisionOptional ...int) orb.LineString {
 	// default to 6 digits of precision
 	precision := 6