add jsonpretty util

Change-Id: Id54b4d892ffda3ad54be3755d38d1c0088b977f2

util/jsonpretty.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+)
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Printf("usage: jsonpretty input.json [output.json]\n")
+		os.Exit(1)
+	}
+
+	buf, err := ioutil.ReadFile(os.Args[1])
+	if err != nil {
+		fmt.Printf("%v\n", err)
+		os.Exit(1)
+	}
+
+	var jsmap map[string]interface{}
+	if err := json.Unmarshal(buf, &jsmap); err != nil {
+		fmt.Printf("%v\n", err)
+		os.Exit(1)
+	}
+
+	for key, val := range jsmap {
+		switch tval := val.(type) {
+		case map[string]interface{}:
+			if len(tval) == 0 {
+				delete(jsmap, key)
+			}
+		case []interface{}:
+			if len(tval) == 0 {
+				delete(jsmap, key)
+			}
+		}
+	}
+
+	buf, err = json.MarshalIndent(jsmap, "", "\t")
+	if err != nil {
+		fmt.Printf("%v\n", err)
+		os.Exit(1)
+	}
+	buf = append(buf, '\n')
+
+	if len(os.Args) == 3 {
+		ioutil.WriteFile(os.Args[2], buf, 0666)
+	} else {
+		os.Stdout.Write(buf)
+	}
+}