add LineString function

geom/geom.go

@@ -0,0 +1,19 @@
+package geom
+
+import (
+	"gogeos"
+	"goposm/element"
+)
+
+func LineString(nodes []element.Node) []byte {
+	geos := gogeos.NewGEOS()
+	defer geos.Finish()
+
+	coordSeq := geos.CreateCoordSeq(uint32(len(nodes)), 2)
+	for i, nd := range nodes {
+		coordSeq.SetXY(geos, uint32(i), nd.Long, nd.Lat)
+	}
+	geom := coordSeq.AsLineString(geos)
+	defer geos.Destroy(geom)
+	return geos.AsWKB(geom)
+}

geom/geom_test.go

@@ -0,0 +1,30 @@
+package geom
+
+import (
+	"goposm/element"
+	"regexp"
+	"testing"
+)
+
+func _TestLineString(t *testing.T) {
+	nodes := make([]element.Node, 2)
+	nodes[0] = element.Node{Lat: 0, Long: 0}
+	nodes[1] = element.Node{Lat: 0, Long: 10}
+	wkt := LineString(nodes)
+	re := regexp.MustCompile("LINESTRING \\(0\\.0* 0\\.0*, 10\\.0* 0\\.0*\\)")
+	if !re.Match(wkt) {
+		t.Errorf("%#v", wkt)
+	}
+}
+
+func BenchmarkLineString(b *testing.B) {
+	size := 16
+	nodes := make([]element.Node, size)
+	for i := 0; i < size; i++ {
+		nodes[i] = element.Node{Lat: 0, Long: float64(i)}
+	}
+
+	for i := 0; i < b.N; i++ {
+		LineString(nodes)
+	}
+}