encoding/json: use reflect.Value.IsZero

IsZero does the same thing, using this rather than writing it again.

Follow-up to #63519

Change-Id: I93768874052935dd7cb58804f22748091bcc3ef7
GitHub-Last-Rev: dfbc6ed
GitHub-Pull-Request: #63540
Reviewed-on: https://go-review.googlesource.com/c/go/+/535415
Auto-Submit: Ian Lance Taylor <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Joseph Tsai <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: andig

src/encoding/json/encode.go

@@ -307,16 +307,12 @@ func isEmptyValue(v reflect.Value) bool {
 	switch v.Kind() {
 	case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
 		return v.Len() == 0
-	case reflect.Bool:
-		return v.Bool() == false
-	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		return v.Int() == 0
-	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		return v.Uint() == 0
-	case reflect.Float32, reflect.Float64:
-		return v.Float() == 0
-	case reflect.Interface, reflect.Pointer:
-		return v.IsNil()
+	case reflect.Bool,
+		reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
+		reflect.Float32, reflect.Float64,
+		reflect.Interface, reflect.Pointer:
+		return v.IsZero()
 	}
 	return false
 }