Added more error handling and necessary functions

link.go

@@ -9,17 +9,39 @@ import (
 type Link struct {
 	XMLName xml.Name `xml:"link"`
 	*CommonAttributes
-	Title    string      `xml:"title,attr,omitempty"`
-	Href     IRI         `xml:"href,attr"`
-	Rel      string      `xml:"rel,attr,omitempty"`
-	Type     MediaType   `xml:"type,attr,omitempty"`
-	HrefLang LanguageTag `xml:"hreflang,attr,omitempty"`
-	Length   uint        `xml:"length,attr,omitempty"`
+	Title    string `xml:"title,attr,omitempty"`
+	Href     string `xml:"href,attr"` // IRI
+	Rel      string `xml:"rel,attr,omitempty"`
+	Type     string `xml:"type,attr,omitempty"`     // MediaType
+	HrefLang string `xml:"hreflang,attr,omitempty"` // LanguageTag
+	Length   uint   `xml:"length,attr,omitempty"`
 }
 
-// NewLink creates a new Link. It returns a *Link.
-func NewLink(href string) *Link {
-	return &Link{Href: IRI(href)}
+// NewLink creates a new Link. It returns a *Link and an error.
+func NewLink(href string) (*Link, error) {
+	if !isValidIRI(href) {
+		return nil, fmt.Errorf("href %v not correctly formatted", href)
+	}
+
+	return &Link{Href: href}, nil
+}
+
+// SetType sets the Type attribute of the Link. It returns an error.
+func (l *Link) SetType(t string) error {
+	if !isValidMediaType(t) {
+		return fmt.Errorf("type %v invalid media type", l)
+	}
+
+	return nil
+}
+
+// SetHrefLang sets the HrefLang attribute of the Link. It returns an error.
+func (l *Link) SetHrefLang(h string) error {
+	if !isValidLanguageTag(h) {
+		return fmt.Errorf("hreflang %v invalid language tag", l)
+	}
+
+	return nil
 }
 
 // Check checks the Link for incompatibilities with RFC4287. It returns an
@@ -34,13 +56,13 @@ func (l *Link) Check() error {
 	}
 
 	if l.Rel != "" {
-		if strings.Contains(l.Rel, ":") && !isValidIRI(IRI(l.Rel)) {
+		if strings.Contains(l.Rel, ":") && !isValidIRI(l.Rel) {
 			return fmt.Errorf("rel attribute of link %v not correctly formatted", l)
 		}
 	}
 
 	if l.Type != "" {
-		if !isValidMediaType(string(l.Type)) {
+		if !isValidMediaType(l.Type) {
 			return fmt.Errorf("type attribute of link %v invalid media type", l)
 		}
 	}