Nicer approach to srcset

guile/broken-link-checker.scm

@@ -40,16 +40,33 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
                           (// video @ src)
                           (// video source @ src)
                           (// audio @ src)
-                          (// audio source @ src))))
+                          (// audio source @ src)
+                          (// picture source @ srcset)
+                          (// img @ srcset))))
+
+;; Special handling for srcset
+(define (parse-srcset s)
+  "Parse out the list of URLs from an image srcset, discarding whitespace and the
+width/density descriptor."
+  (pk s)
+  (map (compose first (cut string-split <> #\space))
+       (map string-trim-both (string-split s #\,))))
 
 (define (extract-links body)
   "Extract links from an HTML document, discarding any tel: or mailto: links."
   (let ((x (html->sxml body)))
     (remove (lambda (s) (or (string-prefix? "tel:" s) (string-prefix? "mailto:" s)))
             (delete-duplicates
-             (map cadr
-                  (concatenate
-                   (map (lambda (f) (f x)) link-paths)))))))
+             (fold (lambda (f accum)
+                     (fold (lambda (x accum)
+                             (match-let (((attr val) x))
+                               (if (equal? attr 'srcset)
+                                   (append (parse-srcset val) accum)
+                                   (cons val accum))))
+                           accum
+                           (f x)))
+                   '()
+                   link-paths)))))
 
 (define (uri-without-fragment uri)
   "If uri has a fragment, return a new URI without the fragment."