(feat)buffer: add customization variables for buffer (#1990)

This commit adds 3 custom variables:

1. org-roam-buffer-postrender-functions

This list of functions are run within the Org-roam buffer after the
Org-roam buffer is rendered. For example, one can produce latex previews
for all content within the Org-roam buffer:

(add-hook
'org-roam-buffer-postrender-functions (lambda () (org--latex-preview-region
(point-min) (point-max))))

2. org-roam-preview-function

This is the function used to extract the content to populate the buffer.
It defaults to `org-roam-preview-default-function`, which extracts all
contents within the headline up to the next headline.

3. org-roam-preview-postprocess-functions

This is a list of functions run to post-process the content retrieved
from org-roam-preview-function. It can be used to strip additional
content from the buffer, or perform sentence-unwrapping.

.dir-locals.el

@@ -10,5 +10,4 @@
                               (org-with-point-at . 1)
                               (magit-insert-section . defun)
                               (magit-section-case . 0)
-                              (->> . 1)
                               (org-roam-with-file . 2)))))

org-roam-mode.el

@@ -48,6 +48,30 @@ Normally this node is `org-roam-buffer-current-node'."
   :group 'org-roam
   :type 'hook)
 
+(defcustom org-roam-buffer-postrender-functions (list)
+  "Functions to run after the Org-roam buffer is rendered.
+Each function accepts no arguments, and is run with the Org-roam
+buffer as the current buffer."
+  :group 'org-roam
+  :type 'hook)
+
+(defcustom org-roam-preview-function #'org-roam-preview-default-function
+  "The preview function to use to populate the Org-roam buffer.
+
+The function takes no arguments, but the point is temporarily set
+to the exact location of the backlink."
+  :group 'org-roam
+  :type 'function)
+
+(defcustom org-roam-preview-postprocess-functions (list #'org-roam-strip-comments)
+  "A list of functions to postprocess the preview content.
+
+Each function takes a single argument, the string for the preview
+content, and returns the post-processed string. The functions are
+applied in order of appearance in the list."
+  :group 'org-roam
+  :type 'hook)
+
 ;;; Faces
 (defface org-roam-header-line
   `((((class color) (background light))
@@ -205,6 +229,7 @@ buffer."
     (magit-insert-section (org-roam)
       (magit-insert-heading)
       (run-hook-with-args 'org-roam-mode-section-functions org-roam-buffer-current-node))
+    (run-hooks org-roam-buffer-postrender-functions)
     (goto-char 0)))
 
 (defun org-roam-buffer-set-header-line-format (string)
@@ -398,81 +423,27 @@ In interactive calls OTHER-WINDOW is set with
     (when (org-invisible-p) (org-show-context))
     buf))
 
+(defun org-roam-preview-default-function ()
+  "Return the preview content at point.
+
+This function returns the all contents under the current
+headline, up to the next headline."
+  (let ((beg (progn (org-roam-end-of-meta-data t)
+                    (point)))
+        (end (progn (org-next-visible-heading 1)
+                    (point))))
+    (string-trim (buffer-substring-no-properties beg end))))
+
 (defun org-roam-preview-get-contents (file pt)
   "Get preview content for FILE at PT."
   (save-excursion
     (org-roam-with-temp-buffer file
       (org-with-wide-buffer
        (goto-char pt)
-       (let ((beg (progn (org-roam-end-of-meta-data t)
-                         (point)))
-             (end (progn (org-next-visible-heading 1)
-                         (point))))
-         (string-trim (buffer-substring-no-properties beg end)))))))
-
-(defun org-roam-preview-get-entry-text (marker n-lines &optional indent)
-  "Extract entry text from MARKER, at most N-LINES lines.
-This will ignore drawers etc, just get the text.
-If INDENT is given, prefix every line with this string."
-  (let (txt ind)
-    (save-excursion
-      (with-current-buffer (marker-buffer marker)
-        (if (not (derived-mode-p 'org-mode))
-            (setq txt "")
-          (org-with-wide-buffer
-           (goto-char marker)
-           (end-of-line 1)
-           (setq txt (buffer-substring
-                      (min (1+ (point)) (point-max))
-                      (progn (outline-next-heading) (point))))
-           (with-temp-buffer
-             (insert txt)
-             (goto-char (point-min))
-             (while (org-activate-links (point-max))
-               (goto-char (match-end 0)))
-             (goto-char (point-min))
-             (while (re-search-forward org-link-bracket-re (point-max) t)
-               (set-text-properties (match-beginning 0) (match-end 0)
-                                    nil))
-             (goto-char (point-min))
-             (while (re-search-forward org-drawer-regexp nil t)
-               (delete-region
-                (match-beginning 0)
-                (progn (re-search-forward
-                        "^[ \t]*:END:.*\n?" nil 'move)
-                       (point))))
-             (goto-char (point-min))
-             (goto-char (point-max))
-             (skip-chars-backward " \t\n")
-             (when (looking-at "[ \t\n]+\\'") (replace-match ""))
-
-             ;; find and remove min common indentation
-             (goto-char (point-min))
-             (untabify (point-min) (point-max))
-             (setq ind (current-indentation))
-             (while (not (eobp))
-               (unless (looking-at "[ \t]*$")
-                 (setq ind (min ind (current-indentation))))
-               (beginning-of-line 2))
-             (goto-char (point-min))
-             (while (not (eobp))
-               (unless (looking-at "[ \t]*$")
-                 (move-to-column ind)
-                 (delete-region (point-at-bol) (point)))
-               (beginning-of-line 2))
-             (goto-char (point-min))
-             (when indent
-               (while (and (not (eobp)) (re-search-forward "^" nil t))
-                 (replace-match indent t t)))
-             (goto-char (point-min))
-             (while (looking-at "[ \t]*\n") (replace-match ""))
-             (goto-char (point-max))
-             (when (> (org-current-line)
-                      n-lines)
-               (org-goto-line (1+ n-lines))
-               (backward-char 1))
-             (setq txt (buffer-substring (point-min) (point))))))))
-    txt))
+       (let ((s (funcall org-roam-preview-function)))
+         (dolist (fn org-roam-preview-postprocess-functions)
+           (setq s (funcall fn s)))
+         s)))))
 
 ;;;; Backlinks
 (cl-defstruct (org-roam-backlink (:constructor org-roam-backlink-create)

org-roam-utils.el

@@ -49,8 +49,8 @@
 (defun org-roam-quote-string (s)
   "Quotes string S."
   (->> s
-    (org-roam-replace-string "\\" "\\\\")
-    (org-roam-replace-string "\"" "\\\"")))
+       (org-roam-replace-string "\\" "\\\\")
+       (org-roam-replace-string "\"" "\\\"")))
 
 (defun org-roam-string-equal (s1 s2)
   "Return t if S1 and S2 are equal.
@@ -59,6 +59,17 @@ Like `string-equal', but case-insensitive."
        (or (string-equal s1 s2)
            (string-equal (downcase s1) (downcase s2)))))
 
+(defun org-roam-strip-comments (s)
+  "Strip Org comments from string S."
+  (with-temp-buffer
+    (insert s)
+    (goto-char (point-min))
+    (while (not (eobp))
+      (if (org-at-comment-p)
+          (delete-region (point-at-bol) (progn (forward-line) (point)))
+        (forward-line)))
+    (buffer-string)))
+
 ;;; List utilities
 (defun org-roam-plist-map! (fn plist)
   "Map FN over PLIST, modifying it in-place and returning it.