Function collectUserTypes

http/codegen/service_data.go:2722–2754

collectUserTypes traverses the given data type recursively and calls back the given function for each attribute using a user type.

(dt expr.DataType, cb func(expr.UserType), seen ...map[string]struct{})

// collectUserTypes traverses the given data type recursively and calls back the
// given function for each attribute using a user type.
func collectUserTypes(dt expr.DataType, cb func(expr.UserType), seen ...map[string]struct{}) {
	if dt == expr.Empty {
		return
	}
	var s map[string]struct{}
	if len(seen) > 0 {
		s = seen[0]
	} else {
		s = make(map[string]struct{})
	}
	switch actual := dt.(type) {
	case *expr.Object:
		for _, nat := range *actual {
			collectUserTypes(nat.Attribute.Type, cb, seen...)
		}
	case *expr.Union:
		for _, nat := range actual.Values {
			collectUserTypes(nat.Attribute.Type, cb, seen...)
		}
	case *expr.Array:
		collectUserTypes(actual.ElemType.Type, cb, seen...)
	case *expr.Map:
		collectUserTypes(actual.KeyType.Type, cb, seen...)
		collectUserTypes(actual.ElemType.Type, cb, seen...)
	case expr.UserType:
		if _, ok := s[actual.ID()]; ok {
			return
		}
		s[actual.ID()] = struct{}{}
		cb(actual)
		collectUserTypes(actual.Attribute().Type, cb, s)
	}
}

func collectHTTPUnionTypes(att *expr.AttributeExpr, scope *codegen.NameScope, unions map[string]*service.UnionTypeData, seen map[string]struct{}) {
	if att == nil || att.Type == expr.Empty {