Initial implementation of json point marshaling and unmarshalling

contour.go

@@ -50,4 +50,4 @@ func (c Contour) Contains(p *Point) bool {
 	}
 
 	return intersections%2 != 0
-}
+}

point.go

@@ -1,6 +1,10 @@
 package geo
 
 import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"log"
 	"math"
 )
 
@@ -93,3 +97,28 @@ func (p *Point) BearingTo(p2 *Point) float64 {
 
 	return brng
 }
+
+// Renders the current Point to valid JSON.
+// Implements the json.Marshaller Interface.
+func (p *Point) MarshalJSON() ([]byte, error) {
+	res := fmt.Sprintf(`{"lat":%v, "lng":%v}`, p.Lat(), p.Lng())
+	return []byte(res), nil
+}
+
+// Decodes the current Point from a JSON body.
+// Throws an error if the body of the point cannot be interpreted by the JSON body
+func (p *Point) UnmarshalJSON(data []byte) error {
+	// TODO throw an error if there is an issue parsing the body.
+	dec := json.NewDecoder(bytes.NewReader(data))
+	var values map[string]float64
+	err := dec.Decode(&values)
+
+	if err != nil {
+		log.Print(err)
+		return err
+	}
+
+	*p = *NewPoint(values["lat"], values["lng"])
+
+	return nil
+}

point_test.go

@@ -1,7 +1,9 @@
 package geo
 
 import (
+	"encoding/json"
 	"fmt"
+	"log"
 	"testing"
 )
 
@@ -87,3 +89,31 @@ func TestBearingTo(t *testing.T) {
 		t.Error("Unnacceptable result.", fmt.Sprintf("%f", bearing))
 	}
 }
+
+func TestMarshalJSON(t *testing.T) {
+	p := NewPoint(40.7486, -73.9864)
+	res, err := json.Marshal(p)
+
+	if err != nil {
+		log.Print(err)
+		t.Error("Should not encounter an error when attempting to Marshal a Point to JSON")
+	}
+
+	if string(res) == "{lat:40.7486, lng:-73.9864}" {
+		t.Error("Point should correctly Marshal to JSON")
+	}
+}
+
+func TestUnmarshalJSON(t *testing.T) {
+	data := []byte(`{"lat":40.7486, "lng":-73.9864}`)
+	p := &Point{}
+	err := p.UnmarshalJSON(data)
+
+	if err != nil {
+		t.Errorf("Should not encounter an error when attempting to Unmarshal a Point from JSON")
+	}
+
+	if p.Lat() != 40.7486 || p.Lng() != -73.9864 {
+		t.Errorf("Point has mismatched data after Unmarshalling from JSON")
+	}
+}

polygon_test.go

@@ -2,8 +2,8 @@ package geo
 
 import (
 	"encoding/json"
-	"testing"
 	"os"
+	"testing"
 )
 
 // Tests a point is in a real geo polygon
@@ -91,4 +91,4 @@ func json2contour(filename string) (*Contour, error) {
 		cont.Add(np)
 	}
 	return cont, err
-}
+}