Performance improvements when rendering

- Fast path for JSON, XML and plain text rendering

render/json.go

@@ -0,0 +1,31 @@
+package render
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+type (
+	jsonRender struct{}
+
+	indentedJSON struct{}
+)
+
+func (_ jsonRender) Render(w http.ResponseWriter, code int, data ...interface{}) error {
+	return WriteJSON(w, code, data[0])
+}
+
+func (_ indentedJSON) Render(w http.ResponseWriter, code int, data ...interface{}) error {
+	WriteHeader(w, code, "application/json")
+	jsonData, err := json.MarshalIndent(data[0], "", "    ")
+	if err != nil {
+		return err
+	}
+	_, err = w.Write(jsonData)
+	return err
+}
+
+func WriteJSON(w http.ResponseWriter, code int, data interface{}) error {
+	WriteHeader(w, code, "application/json")
+	return json.NewEncoder(w).Encode(data)
+}