Add a value hook func

decode_hooks.go

@@ -16,10 +16,11 @@ func typedDecodeHook(h DecodeHookFunc) DecodeHookFunc {
 	// Create variables here so we can reference them with the reflect pkg
 	var f1 DecodeHookFuncType
 	var f2 DecodeHookFuncKind
+	var f3 DecodeHookFuncValue
 
 	// Fill in the variables into this interface and the rest is done
 	// automatically using the reflect package.
-	potential := []interface{}{f1, f2}
+	potential := []interface{}{f1, f2, f3}
 
 	v := reflect.ValueOf(h)
 	vt := v.Type()
@@ -38,13 +39,15 @@ func typedDecodeHook(h DecodeHookFunc) DecodeHookFunc {
 // that took reflect.Kind instead of reflect.Type.
 func DecodeHookExec(
 	raw DecodeHookFunc,
-	from reflect.Type, to reflect.Type,
-	data interface{}) (interface{}, error) {
+	from reflect.Value, to reflect.Value) (interface{}, error) {
+
 	switch f := typedDecodeHook(raw).(type) {
 	case DecodeHookFuncType:
-		return f(from, to, data)
+		return f(from.Type(), to.Type(), from.Interface())
 	case DecodeHookFuncKind:
-		return f(from.Kind(), to.Kind(), data)
+		return f(from.Kind(), to.Kind(), from.Interface())
+	case DecodeHookFuncValue:
+		return f(from, to)
 	default:
 		return nil, errors.New("invalid decode hook signature")
 	}
@@ -56,22 +59,16 @@ func DecodeHookExec(
 // The composed funcs are called in order, with the result of the
 // previous transformation.
 func ComposeDecodeHookFunc(fs ...DecodeHookFunc) DecodeHookFunc {
-	return func(
-		f reflect.Type,
-		t reflect.Type,
-		data interface{}) (interface{}, error) {
+	return func(f reflect.Value, t reflect.Value) (interface{}, error) {
 		var err error
+		var data interface{}
+		newFrom := f
 		for _, f1 := range fs {
-			data, err = DecodeHookExec(f1, f, t, data)
+			data, err = DecodeHookExec(f1, newFrom, t)
 			if err != nil {
 				return nil, err
 			}
-
-			// Modify the from kind to be correct with the new data
-			f = nil
-			if val := reflect.ValueOf(data); val.IsValid() {
-				f = val.Type()
-			}
+			newFrom = reflect.ValueOf(data)
 		}
 
 		return data, nil
@@ -215,3 +212,21 @@ func WeaklyTypedHook(
 
 	return data, nil
 }
+
+func RecursiveStructToMapHookFunc() DecodeHookFunc {
+	return func(f reflect.Value, t reflect.Value) (interface{}, error) {
+		if f.Kind() != reflect.Struct {
+			return f.Interface(), nil
+		}
+
+		var i interface{} = struct{}{}
+		if t.Type() != reflect.TypeOf(&i).Elem() {
+			return f.Interface(), nil
+		}
+
+		m := make(map[string]interface{})
+		t.Set(reflect.ValueOf(m))
+
+		return f.Interface(), nil
+	}
+}