+;; XDG User Directories
+;; https://www.freedesktop.org/wiki/Software/xdg-user-dirs/
+
+(defconst xdg-line-regexp
+ (eval-when-compile
+ (rx "XDG_"
+ (group-n 1 (or "DESKTOP" "DOWNLOAD" "TEMPLATES" "PUBLICSHARE"
+ "DOCUMENTS" "MUSIC" "PICTURES" "VIDEOS"))
+ "_DIR=\""
+ (group-n 2 (or "/" "$HOME/") (*? (or (not (any "\"")) "\\\"")))
+ "\""))
+ "Regexp matching non-comment lines in xdg-user-dirs config files.")
+
+(defvar xdg-user-dirs nil
+ "Alist of directory keys and values.")
+
+(defun xdg--user-dirs-parse-line ()
+ "Return pair of user-dirs key to directory value in LINE, otherwise nil.
+This should be called at the beginning of a line."
+ (skip-chars-forward "[:blank:]")
+ (when (and (/= (following-char) ?#)
+ (looking-at xdg-line-regexp))
+ (let ((k (match-string 1))
+ (v (match-string 2)))
+ (when (and k v) (cons k v)))))
+
+(defun xdg--user-dirs-parse-file (filename)
+ "Return alist of xdg-user-dirs from FILENAME."
+ (let (elt res)
+ (with-temp-buffer
+ (insert-file-contents filename)
+ (goto-char (point-min))
+ (while (not (eobp))
+ (setq elt (xdg--user-dirs-parse-line))
+ (when (consp elt) (push elt res))
+ (forward-line)))
+ res))
+
+(defun xdg-user-dir (name)
+ "Return the path of user directory referred to by NAME."
+ (when (null xdg-user-dirs)
+ (setq xdg-user-dirs
+ (xdg--user-dirs-parse-file
+ (expand-file-name "user-dirs.dirs" (xdg-config-home)))))
+ (cdr (assoc name xdg-user-dirs)))
This parsing seems a bit brittle (what if the file contains ${HOME} instead of $HOME?); probably this should call the xdg-user-dir program instead.