96 lines
2.5 KiB
Go
96 lines
2.5 KiB
Go
package atom
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import (
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"errors"
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"fmt"
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"strings"
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)
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type Link struct {
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*CommonAttributes
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Title string `xml:"title,attr,omitempty"`
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Content Content `xml:"content"` // undefinedContent in RFC4287
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Href IRI `xml:"href,attr"`
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Rel string `xml:"rel,attr,omitempty"`
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Type MediaType `xml:"type,attr,omitempty"`
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HrefLang LanguageTag `xml:"hreflang,attr,omitempty"`
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Length uint `xml:"length,attr,omitempty"`
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}
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// NewLink creates a new Link. It returns a *Link and an error.
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func NewLink(href string) (*Link, error) {
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content, err := NewContent(InlineText, "", "")
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if err != nil {
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return nil, fmt.Errorf("error creating content element: %v", err)
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}
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return &Link{Href: IRI(href), Content: content}, nil
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}
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// Check checks the Link for incompatibilities with RFC4287. It returns an
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// error.
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func (l *Link) Check() error {
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if l.Href == "" {
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return errors.New("href attribute of link empty")
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} else {
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if !isValidIRI(l.Href) {
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return fmt.Errorf("href attribute %v of link not correctly formatted", l.Href)
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}
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}
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if strings.Contains(l.Rel, ":") && !isValidIRI(IRI(l.Rel)) {
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return fmt.Errorf("rel attribute %v of link %v not correctly formatted", l.Rel, l.Href)
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}
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if !isValidMediaType(string(l.Type)) {
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return fmt.Errorf("type attribute %v of link %v invalid media type", l.Type, l.Href)
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}
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if !isValidLanguageTag(l.HrefLang) {
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return fmt.Errorf("hreflang attribute %v of link %v invalid language tag", l.Type, l.HrefLang)
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}
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if l.Content == nil {
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return fmt.Errorf("no content element of link %v", l.Href)
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} else {
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if err := l.Content.Check(); err != nil {
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return fmt.Errorf("content element of link %v: %v", l.Href, err)
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}
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}
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return nil
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}
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// hasAlternateDuplicateLinks checks whether multiple Links with Rel
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// "alternate" also have Type and HrefLang in common. It returns a bool.
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// atom:feed/entry elements MUST NOT contain more than one atom:link element
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// with a rel attribute value of "alternate" that has the same combination of
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// type and hreflang attribute values.
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func hasAlternateDuplicateLinks(l []*Link) bool {
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linkMap := make(map[string]bool)
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for _, link := range l {
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if link.Rel == "alternate" {
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key := fmt.Sprint(link.Type, "|", link.HrefLang)
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if linkMap[key] {
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return true
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}
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linkMap[key] = true
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}
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}
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return false
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}
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// alternateRelExists checks whether multiple Links with Rel "alternate" exist.
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// It returns a bool.
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func alternateRelExists(l []*Link) bool {
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for _, link := range l {
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if link.Rel == "alternate" {
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return true
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}
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}
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return false
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}
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