refactor: yet another one, someday I might be happy

multi.go

@@ -6,17 +6,17 @@ import (
 	"io"
 )
 
-// MultiRenderer is a renderer that tries multiple renderers until one succeeds.
-type MultiRenderer struct {
+// Multi is a renderer that tries multiple renderers until one succeeds.
+type Multi struct {
 	Renderers []FormatRenderer
 }
 
-var _ FormatRenderer = (*MultiRenderer)(nil)
+var _ FormatRenderer = (*Multi)(nil)
 
 // Render tries each renderer in order until one succeeds. If none succeed,
 // ErrCannotRender is returned. If a renderer returns an error that is not
 // ErrCannotRender, that error is returned.
-func (mr *MultiRenderer) Render(w io.Writer, v any) error {
+func (mr *Multi) Render(w io.Writer, v any) error {
 	for _, r := range mr.Renderers {
 		err := r.Render(w, v)
 		if err == nil {
@@ -29,3 +29,22 @@ func (mr *MultiRenderer) Render(w io.Writer, v any) error {
 
 	return fmt.Errorf("%w: %T", ErrCannotRender, v)
 }
+
+func (mr *Multi) Formats() []string {
+	formats := make(map[string]struct{})
+
+	for _, r := range mr.Renderers {
+		if x, ok := r.(Formats); ok {
+			for _, f := range x.Formats() {
+				formats[f] = struct{}{}
+			}
+		}
+	}
+
+	result := make([]string, 0, len(formats))
+	for f := range formats {
+		result = append(result, f)
+	}
+
+	return result
+}