(Emacs/elisp)~massively reworked bookmarking system

Now it can:
- cache results until bookmarks file is modified, so we don't need to
open the file again if we've already figured everything out.  This is
in-memory and not as a file

- a proper dispatching list which has pairs of form (PATTERNS . FUNC)
so the dispatching system is a bit more abstract and easier to add to

- use a URL property in org headings to get the bookmark URL rather
than having it as part of the body of the entry.  This means the body
is now free to house any content without affecting the overall
function of the system, such as notes or subtrees for related
bookmarks.

Emacs/.config/emacs/elisp/org-bookmark.el

@@ -28,69 +28,110 @@
 (defvar +bookmark/file (expand-file-name (concat org-directory "/bookmarks.org")))
 (defvar +bookmark/mpv-args "--ytdl-raw-options=force-ipv4= --ytdl-format=22 -v")
 
-(defun +bookmark/--extract-heading ()
+(defun +bookmark/--get-heading-data ()
+  "In an org-mode buffer, with point on a heading: get the title,
+tags and url."
   (let ((heading-components (org-heading-components))
-        (tags (org-get-tags)))
-    (message "%s" tags)
+        (tags (org-get-tags))
+        (url (org-entry-get (point-marker) "URL")))
     (list
      (nth 4 heading-components)
      (cl-remove-if #'(lambda (tag) (string= tag "bookmark")) tags)
-     (substring-no-properties
-      (org-agenda-get-some-entry-text
-       (point-marker)
-       most-positive-fixnum)))))
+     url)))
 
-(defun +bookmark/--extract-all-heading-data ()
+(defun +bookmark/--get-all-heading-data ()
+  "In an org-mode buffer, get all the heading data (titles, tags and
+urls)."
   (cl-remove-if
    #'(lambda (x) (member "DONE" (nth 1 x)))
+   ;; Extract all headings with :bookmark: tag
    (org-scan-tags
-    #'+bookmark/--extract-heading
+    #'+bookmark/--get-heading-data
     (cdr (org-make-tags-matcher ":bookmark:"))
     nil)))
 
-(defun +bookmark/--heading->record (heading)
-  (cl-destructuring-bind (name tags url) heading
+(defun +bookmark/--format-heading-data (data)
+  "Format the heading data extracted into a pair of (TITLE+TAG
+. URL)."
+  (cl-destructuring-bind (name tags url) data
     (cons
-     (concat name
-             " "
+     (format "%s %s" name
              (substring-no-properties
               (cl-reduce #'(lambda (x y) (concat x ":" y))
                          tags
                          :initial-value "")))
      url)))
 
+(defvar +bookmark/--cache nil
+  "Cached alist constructed from bookmarks file of form (TITLE+TAG
+. URL).")
+(defvar +bookmark/--cache-last-modified nil
+  "Last modified time for bookmarks file as a float.")
+
 (defun +bookmark/bookmarks ()
+  "Get all bookmarks from +BOOKMARK/FILE in alist format.  Results
+are cached for faster lookup."
   (with-current-buffer (find-file-noselect +bookmark/file)
-    (mapcar
-     #'+bookmark/--heading->record
-     (+bookmark/--extract-all-heading-data))))
+    (let ((cur-last-modified (float-time (visited-file-modtime))))
+      ;; If no cache, or no last-modified or the file has been modified
+      ;; since we've last cached then recache.
+      (when (or (null +bookmark/--cache)
+               (null +bookmark/--cache-last-modified)
+               (not (= cur-last-modified +bookmark/--cache-last-modified)))
+        (setq +bookmark/--cache-last-modified cur-last-modified
+              +bookmark/--cache (mapcar
+                                 #'+bookmark/--format-heading-data
+                                 (+bookmark/--get-all-heading-data))))))
+  +bookmark/--cache)
+
+(defun +bookmark/open-mpv (url)
+  (interactive)
+  (message "[bookmark]: Starting MPV process")
+  (with-current-buffer (get-buffer-create "*mpv*")
+    (ansi-color-for-comint-mode-on)
+    (comint-mode))
+  (set-process-filter (start-process-shell-command
+                       "bookmark-mpv" "*mpv*"
+                       (concat "mpv " +bookmark/mpv-args " \"" url "\""))
+                      #'comint-output-filter))
+
+(defconst +bookmark/dispatch-list
+  '((("^https://\\(www.\\)?youtu\\(.\\)?be"
+      "\\.mp4$")
+     . +bookmark/open-mpv)
+    (otherwise . eww))
+  "List of pairs of type (PATTERNS . FUNC) which is used in
++BOOKMARK/OPEN-BOOKMARK to handle opening urls.
+
+PATTERNS is a list of one or more regexp patterns (as strings)
+which should match particular URLs.  It can also be 'OTHERWISE
+which represents the default case if no previous patterns match
+the URL.
+
+FUNC is a callable or function which takes one parameter (the URL
+as a string) and produces some action of opening it.")
 
 (defun +bookmark/open-bookmark ()
+  "Open a bookmark.  Uses +BOOKMARK/DISPATCH-LIST to dispatch
+opening the url to some handler function."
   (interactive)
   (let* ((bookmarks (+bookmark/bookmarks))
-         (choice (completing-read "Choose bookmark: "
-                                  (mapcar #'car bookmarks)
-                                  nil t))
+         (choice (completing-read "Choose bookmark: " (mapcar #'car bookmarks) nil t))
          (pair (assoc choice bookmarks #'string=)))
     (if (null pair)
         (error (format "`%s' is not a valid bookmark" choice))
-      (message "[bookmark]: Opening `%s`" (car pair))
-      (cond
-       ((or
-         (string-match-p "^https://\\(www.\\)?youtu\\(.\\)?be" (cdr pair))
-         (string-match-p "\\.mp4$" (cdr pair)))
-        ;; Open MPV
-        (message "[bookmark]: Starting MPV process")
-        (with-current-buffer (get-buffer-create "*mpv*")
-          (ansi-color-for-comint-mode-on)
-          (comint-mode))
-        (set-process-filter (start-process-shell-command
-                             "bookmark-mpv" "*mpv*"
-                             (concat "mpv " +bookmark/mpv-args " \"" (cdr pair) "\""))
-                            #'comint-output-filter))
-       (t
-        (message "[bookmark]: Starting eww")
-        (eww (cdr pair)))))))
+      (message "[bookmark]: Opening `%s` (`%s`)" (car pair) (cdr pair))
+      (let* ((url (cdr pair))
+             (dispatch-choice
+              (cl-loop
+               for (patterns . func) in +bookmark/dispatch-list
+               if (or (eq patterns 'otherwise)
+                     (cl-some
+                      #'(lambda (pattern) (string-match pattern url))
+                      patterns))
+               return func)))
+        (message "dispatch-choice=%S" dispatch-choice)
+        (funcall dispatch-choice (cdr pair))))))
 
 (provide 'org-bookmark)
 ;;; bookmark.el ends here