category.go

@@ -8,14 +8,19 @@ import (
 
 type Category struct {
 	*CommonAttributes
-	Content string `xml:",any"` // undefinedContent in RFC4287
+	Content Content `xml:"content"` // undefinedContent in RFC4287
-	Term    string `xml:"term,attr"`
+	Term    string  `xml:"term,attr"`
-	Scheme  IRI    `xml:"scheme,attr,omitempty"`
+	Scheme  IRI     `xml:"scheme,attr,omitempty"`
-	Label   string `xml:"label,attr,omitempty"`
+	Label   string  `xml:"label,attr,omitempty"`
 }
 
 // NewCategory creates a new Category. It returns a *Category and an error.
-func NewCategory(term, content string) (*Category, error) {
+func NewCategory(term string) (*Category, error) {
+	content, err := NewContent(InlineText, "", "")
+	if err != nil {
+		return nil, fmt.Errorf("error creating content element: %v", err)
+	}
+
 	return &Category{Term: term, Content: content}, nil
 }
 
@@ -41,8 +46,12 @@ func (c *Category) Check() error {
 		return fmt.Errorf("label attribute %v of category not correctly escaped", c.Label)
 	}
 
-	if c.Content == "" {
+	if c.Content == nil {
-		return errors.New("content element of category empty")
+		return errors.New("no content element of category")
+	} else {
+		if err := c.Content.Check(); err != nil {
+			return fmt.Errorf("content element of category: %v", err)
+		}
 	}
 
 	return nil

inlineTextContent.go

@@ -3,6 +3,7 @@ package atom
 import (
 	"errors"
 	"fmt"
+	"reflect"
 )
 
 type InlineTextContent struct {
@@ -18,12 +19,11 @@ func newInlineTextContent(mediaType string, content any) (*InlineTextContent, er
 		return nil, fmt.Errorf("media type %v incompatible with inline text content", mediaType)
 	}
 
-	text, ok := content.(string)
+	if reflect.TypeOf(content).Kind() != reflect.String {
-	if !ok {
 		return nil, fmt.Errorf("content type %T incompatible with inline text content", content)
 	}
 
-	return &InlineTextContent{Type: mediaType, Text: text}, nil
+	return &InlineTextContent{Type: mediaType, Text: content.(string)}, nil
 }
 
 // isContent checks whether the InlineTextContent is a Content. It returns a

inlineXHTMLContent.go

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

link.go

@@ -9,7 +9,7 @@ import (
 type Link struct {
 	*CommonAttributes
 	Title    string      `xml:"title,attr,omitempty"`
-	Content  string      `xml:",any"` // undefinedContent in RFC4287
+	Content  Content     `xml:"content"` // undefinedContent in RFC4287
 	Href     IRI         `xml:"href,attr"`
 	Rel      string      `xml:"rel,attr,omitempty"`
 	Type     MediaType   `xml:"type,attr,omitempty"`
@@ -18,7 +18,12 @@ type Link struct {
 }
 
 // NewLink creates a new Link. It returns a *Link and an error.
-func NewLink(href, content string) (*Link, error) {
+func NewLink(href string) (*Link, error) {
+	content, err := NewContent(InlineText, "", "")
+	if err != nil {
+		return nil, fmt.Errorf("error creating content element: %v", err)
+	}
+
 	return &Link{Href: IRI(href), Content: content}, nil
 }
 
@@ -51,8 +56,12 @@ func (l *Link) Check() error {
 		}
 	}
 
-	if l.Content == "" {
+	if l.Content == nil {
-		return errors.New("content element of link empty")
+		return fmt.Errorf("no content element of link %v", l.Href)
+	} else {
+		if err := l.Content.Check(); err != nil {
+			return fmt.Errorf("content element of link %v: %v", l.Href, err)
+		}
 	}
 
 	return nil

outOfLineContent.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"mime"
+	"reflect"
 )
 
 type OutOfLineContent struct {
@@ -19,16 +20,15 @@ func newOutOfLineContent(mediaType string, content any) (*OutOfLineContent, erro
 		return nil, fmt.Errorf("media type %v incompatible with out of line content", mediaType)
 	}
 
-	iri, ok := content.(IRI)
+	if reflect.TypeOf(content).Kind() != reflect.String {
-	if !ok {
 		return nil, fmt.Errorf("content type %T incompatible with out of line content", content)
 	}
 
-	if !isValidIRI(iri) {
+	if !isValidIRI(content.(IRI)) {
 		return nil, errors.New("content not a valid uri")
 	}
 
-	return &OutOfLineContent{Type: MediaType(mediaType), SRC: iri}, nil
+	return &OutOfLineContent{Type: MediaType(mediaType), SRC: content.(IRI)}, nil
 }
 
 // isContent checks whether the OutOfLineContent is a Content. It returns a

xhtmlDiv.go

@@ -1,30 +0,0 @@
-package atom
-
-import (
-	"encoding/xml"
-	"errors"
-)
-
-type XHTMLDiv struct {
-	XMLName xml.Name `xml:"div"`
-	XMLNS   string   `xml:"xmlns,attr"`
-	Content string   `xml:",innerxml"`
-}
-
-// NewXHTMLDiv creates a new XHTMLDiv. It returns a *XHTMLDiv.
-func NewXHTMLDiv(content string) *XHTMLDiv {
-	return &XHTMLDiv{
-		XMLNS:   "http://www.w3.org/1999/xhtml",
-		Content: content,
-	}
-}
-
-// Check checks the XHTMLDiv for incompatibilities with RFC4287. It returns an
-// error.
-func (x *XHTMLDiv) Check() error {
-	if x.XMLNS != "http://www.w3.org/1999/xhtml" {
-		return errors.New("xmlns attribute of xhtml text must be http://www.w3.org/1999/xhtml")
-	}
-
-	return nil
-}

xhtmlText.go

@@ -1,10 +1,16 @@
 package atom
 
 import (
+	"encoding/xml"
 	"errors"
-	"fmt"
 )
 
+type XHTMLDiv struct {
+	XMLName xml.Name `xml:"div"`
+	XMLNS   string   `xml:"xmlns,attr"`
+	Content string   `xml:",innerxml"`
+}
+
 type XHTMLText struct {
 	*CommonAttributes
 	Type     string `xml:"type,attr"` // Must be xhtml
@@ -21,8 +27,8 @@ func (x *XHTMLText) Check() error {
 		return errors.New("type attribute of xhtml text must be xhtml")
 	}
 
-	if err := x.XHTMLDiv.Check(); err != nil {
+	if x.XHTMLDiv.XMLNS != "http://www.w3.org/1999/xhtml" {
-		return fmt.Errorf("xhtml div element %v of xhtml text %v: %v", x.XHTMLDiv, x, err)
+		return errors.New("xmlns attribute of xhtml text must be http://www.w3.org/1999/xhtml")
 	}
 
 	return nil