feat(ipub,ast)!: BaseElement marshaller

ipub/ast/ast.go

@@ -36,6 +36,7 @@ type Element interface {
 	InsertBefore(self, v1, insertee Element)
 	InsertAfter(self, v1, insertee Element)
 
+	xml.Marshaler
 	xml.Unmarshaler
 }
 
@@ -182,7 +183,7 @@ func (e *BaseElement) InsertBefore(self, v1, insertee Element) {
 	}
 }
 
-func (e *BaseElement) UnmarshalChildren(self Element, d *xml.Decoder, start xml.StartElement) error {
+func (e *BaseElement) UnmarshalXMLElement(self Element, d *xml.Decoder, start xml.StartElement) error {
 	elErr := fmt.Errorf("unable to unmarshal element kind %q", self.Kind())
 
 	if n := self.Name(); n != (xml.Name{}) {
@@ -232,6 +233,38 @@ func (e *BaseElement) UnmarshalChildren(self Element, d *xml.Decoder, start xml.
 	}
 }
 
+func (e *BaseElement) MarshalXMLElement(self Element, enc *xml.Encoder, start xml.StartElement) error {
+	elErr := fmt.Errorf("unable to marshal element kind %q", self.Kind())
+
+	if n := self.Name(); n != (xml.Name{}) {
+		start.Name = self.Name()
+	}
+
+	ka, err := self.Kind().MarshalXMLAttr(elementKindAttrName)
+	if err != nil {
+		return errors.Join(elErr, err)
+	}
+
+	start.Attr = append(start.Attr, ka)
+
+	data := struct {
+		Children []Element `xml:",any"`
+	}{Children: []Element{}}
+
+	for c := self.FirstChild(); c != nil; {
+		data.Children = append(data.Children, c)
+		c = c.NextSibling()
+	}
+
+	err = enc.EncodeElement(&data, start)
+	if err != nil && err != io.EOF {
+		return err
+		return errors.Join(elErr, err)
+	}
+
+	return nil
+}
+
 func ensureIsolated(e Element) {
 	if p := e.Parent(); p != nil {
 		p.RemoveChild(p, e)

ipub/ast/content.go

@@ -19,7 +19,11 @@ func (e Content) Kind() ElementKind {
 	return KindContent
 }
 
-func (n *Content) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
-	return n.UnmarshalChildren(n, d, start)
+func (e *Content) MarshalXML(enc *xml.Encoder, start xml.StartElement) error {
+	return e.MarshalXMLElement(e, enc, start)
+}
+
+func (e *Content) UnmarshalXML(dec *xml.Decoder, start xml.StartElement) error {
+	return e.UnmarshalXMLElement(e, dec, start)
 }
 

ipub/ast/errors.go

@@ -0,0 +1,36 @@
+package ast
+
+import (
+	"encoding/xml"
+	"fmt"
+)
+
+type ErrInvalidAttrName struct {
+	Actual   xml.Name
+	Expected xml.Name
+}
+
+var _ error = ErrInvalidAttrName{}
+
+func (err ErrInvalidAttrName) Error() string {
+	return fmt.Sprintf("attribute %q has invalid name, expected %q", fmtXMLName(err.Expected), fmtXMLName(err.Actual))
+}
+
+type ErrInvalidAttrValue struct {
+	Attr    xml.Attr
+	Message string
+}
+
+var _ error = ErrInvalidAttrValue{}
+
+func (err ErrInvalidAttrValue) Error() string {
+	return fmt.Sprintf("attribute %q's value %q is invalid: %s", fmtXMLName(err.Attr.Name), err.Attr.Value, err.Message)
+}
+
+func fmtXMLName(n xml.Name) string {
+	s := n.Local
+	if n.Space != "" {
+		s = fmt.Sprintf("%s:%s", n.Space, n.Local)
+	}
+	return s
+}

ipub/ast/section.go

@@ -5,7 +5,8 @@ import (
 )
 
 type Section struct {
-	Body Body `xml:"body"`
+	XMLName xml.Name `xml:"html"`
+	Body    *Body    `xml:"body"`
 }
 
 type Body struct {
@@ -22,6 +23,10 @@ func (e Body) Kind() ElementKind {
 	return KindBody
 }
 
-func (n *Body) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
-	return n.UnmarshalChildren(n, d, start)
+func (e *Body) MarshalXML(enc *xml.Encoder, start xml.StartElement) error {
+	return e.MarshalXMLElement(e, enc, start)
+}
+
+func (e *Body) UnmarshalXML(dec *xml.Decoder, start xml.StartElement) error {
+	return e.UnmarshalXMLElement(e, dec, start)
 }