Streamline type check in content constructs

inlineXHTMLContent.go

@@ -3,13 +3,12 @@ package atom
 import (
 	"errors"
 	"fmt"
-	"reflect"
 )
 
 type InlineXHTMLContent struct {
 	*CommonAttributes
 	Type     string `xml:"type,attr"`
-	XHTMLDiv string `xml:"xhtmldiv"`
+	XHTMLDiv XHTMLDiv
 }
 
 // newInlineXHTMLContent creates a new InlineXHTMLContent. It returns a
@@ -19,11 +18,12 @@ func newInlineXHTMLContent(mediaType string, content any) (*InlineXHTMLContent,
 		return nil, fmt.Errorf("media type %v incompatible with inline xhtml content", mediaType)
 	}
 
-	if reflect.TypeOf(content).Kind() != reflect.String {
+	xhtmlDiv, ok := content.(XHTMLDiv)
+	if !ok {
 		return nil, fmt.Errorf("content type %T incompatible with inline xhtml content", content)
 	}
 
-	return &InlineXHTMLContent{Type: mediaType, XHTMLDiv: content.(string)}, nil
+	return &InlineXHTMLContent{Type: mediaType, XHTMLDiv: xhtmlDiv}, nil
 }
 
 // isContent checks whether the InlineXHTMLContent is a Content. It returns a
@@ -44,8 +44,8 @@ func (i *InlineXHTMLContent) Check() error {
 		return errors.New("type attribute of inline xhtml content must be xhtml")
 	}
 
-	if i.XHTMLDiv == "" {
-		return errors.New("xhtmlDiv element of inline xhtml content empty")
+	if err := i.XHTMLDiv.Check(); err != nil {
+		return fmt.Errorf("xhtml div element %v of inline xhtml content %v: %v", i.XHTMLDiv, i, err)
 	}
 
 	return nil