[PATCH] Add mode for automatically unhiding emphasis markers in the current region

[Shankar Rao <shankar.rao@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 7251 bytes --]

* lisp/org.el:
(org-auto-emphasis-unhide-at-point): Parameter that controls the
behavior of Org Auto Emphasis mode.  It can be one of the values nil, t, and
'right-edge, and works similarly to the parameter
`prettify-symbols-unprettify-at-point' for `prettify-symbols-mode'.
(org-do-emphasis-faces): When hiding emphasis markers, add additional
text properties 'org-emph-start and org-emph-end to the emphasized
region.
(org-auto-emphasis--current-region-bounds): Local variable containing
the bounds of the region whose emphasis markers are currently
unhidden.
(org-auto-emphasis--get-prop-as-list): Helper function that returns
Org Auto Emphasis properties as a list.
(org-auto-emphasis--post-command-hook): Function added to
`post-command-hook' that rehides emphasis markers for the previous
region and unhides emphasis marks for the current region.
(org-auto-emphasis-mode): Toggles Org Auto Emphasis mode.  Can be
added to `org-mode-hook' to be enabled for all org-mode files.

This code was adapted from prettify-symbols-mode in prog-mode.el

I have not yet signed the papers assigning copyright to the FSF.  I sent a
request for the papers to assign@gnu.org, but have not yet received a
response.

Shankar Rao

---
 lisp/org.el | 98 +++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 87 insertions(+), 11 deletions(-)

diff --git a/lisp/org.el b/lisp/org.el
index 7ff7ec685..870c5c958 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -3644,6 +3644,19 @@ following symbols:
   :type 'boolean
   :safe #'booleanp)

+(defcustom org-auto-emphasis-unhide-at-point nil
+  "If non-nil, unhide the emphasis markers for the region when point is on
it.
+If set to the symbol `right-edge', also unhide the emphasis
+markers if point is immediately after the emphasized region.  The
+emphasis markers will be rehidden as soon as point moves away
+from the region.  If set to nil, the emphasis markers remain
+hidden even when point is in the region."
+  :version "25.1"
+  :type '(choice (const :tag "Never unhide emphasis markers" nil)
+                 (const :tag "Unhide emphasis markers when point is
inside" t)
+                 (const :tag "Unhide emphasis markers when point is inside
or at right edge" right-edge))
+  :group 'org-appearance)
+
 (defcustom org-hide-macro-markers nil
   "Non-nil mean font-lock should hide the brackets marking macro calls."
   :group 'org-appearance
@@ -5056,12 +5069,77 @@ stacked delimiters is N.  Escaping delimiters is
not possible."
    '(font-lock-multiline t org-emphasis t))
       (when (and org-hide-emphasis-markers
  (not (org-at-comment-p)))
- (add-text-properties (match-end 4) (match-beginning 5)
-     '(invisible org-link))
- (add-text-properties (match-beginning 3) (match-end 3)
-     '(invisible org-link)))
+ (let ((s1 (match-beginning 3))
+      (e1 (match-end 3))
+      (s2 (match-end 4))
+      (e2 (match-beginning 5)))
+  (add-text-properties s2 e2 '(invisible org-link))
+  (add-text-properties s1 e1 '(invisible org-link))
+  (add-text-properties s1 e2
+       `(org-emph-start ,s1 org-emph-end ,e2))))
       (throw :exit t))))))))

+(defvar-local org-auto-emphasis--current-region-bounds nil)
+
+(defun org-auto-emphasis--get-prop-as-list (prop)
+  "Helper function to get org-auto-emphasis properties as a list.
+If `org-auto-emphasis-unhide-at-point' is set to `t' then return
+the text property PROP at point in a list. If
+`org-auto-emphasis-unhide-at-point' is set to `right-edge', the
+also include the text property PROP at point-1 unless we are at
+the beginning of the buffer."
+  (remove nil
+  (list (get-text-property (point) prop)
+ (when (and (eq org-auto-emphasis-unhide-at-point 'right-edge)
+   (not (bobp)))
+  (get-text-property (1- (point)) prop)))))
+
+(defun org-auto-emphasis--post-command-hook ()
+  ;; Rehide emphasis markers for the previous region.
+  (when (and org-auto-emphasis--current-region-bounds
+     (or (< (point) (car org-auto-emphasis--current-region-bounds))
+ (> (point) (cadr org-auto-emphasis--current-region-bounds))
+ (and (not (eq org-auto-emphasis-unhide-at-point 'right-edge))
+      (= (point) (cadr org-auto-emphasis--current-region-bounds)))))
+ (apply #'font-lock-flush org-auto-emphasis--current-region-bounds)
+ (setq org-auto-emphasis--current-region-bounds nil))
+  ;; Unhide emphasis markers for the current region.
+  (when-let* ((s (org-auto-emphasis--get-prop-as-list 'org-emph-start))
+      (e (org-auto-emphasis--get-prop-as-list 'org-emph-end))
+      (s (apply #'min s))
+      (e (apply #'max e)))
+    (with-silent-modifications
+      (setq org-auto-emphasis--current-region-bounds (list s e))
+      (remove-text-properties s (1+ s) '(invisible org-link))
+      (remove-text-properties (1- e) e '(invisible org-link)))))
+
+(define-minor-mode org-auto-emphasis-mode
+  "Toggle Org Auto Emphasis mode.
+This mode, when enabled, unhides emphasis markers for the region
+at point, depending on the value of
+`org-auto-emphasis-unhide-at-point'. With a prefix argument ARG,
+enable Org Auto Emphasis mode if ARG is positive, and disable it
+otherwise.  If called from Lisp, enable the mode if ARG is
+omitted or nil.
+
+To enable this in all org-mode files, add the following line to init.el:
+
+  (add-hook 'org-mode #'org-auto-emphasis-mode)
+"
+  :init-value nil
+  (if org-auto-emphasis-mode
+      ;; Turn on
+      (progn
+        (setq-local font-lock-extra-managed-props
+                    (append font-lock-extra-managed-props
+                            '(org-emph-start org-emph-end)))
+        (when org-auto-emphasis-unhide-at-point
+          (add-hook 'post-command-hook
+                    #'org-auto-emphasis--post-command-hook nil t))
+        (font-lock-flush))
+    ;; Turn off
+    (remove-hook 'post-command-hook #'org-auto-emphasis--post-command-hook
t)))
+
 (defun org-emphasize (&optional char)
   "Insert or change an emphasis, i.e. a font like bold or italic.
 If there is an active region, change that region to a new emphasis.
@@ -20482,16 +20560,15 @@ With ARG, repeats or can move backward if
negative."
    (beginning-of-line))
   (_ nil)))
       (cl-incf arg))
-    (while (and (> arg 0) (re-search-forward regexp nil t))
+    (while (and (> arg 0) (re-search-forward regexp nil :move))
       (pcase (get-char-property-and-overlay (point) 'invisible)
  (`(outline . ,o)
  (goto-char (overlay-end o))
- (skip-chars-forward " \t\n")
- (end-of-line))
+ (end-of-line 2))
  (_
  (end-of-line)))
       (cl-decf arg))
-    (if (> arg 0) (goto-char (point-max)) (beginning-of-line))))
+    (when (/= arg initial-arg) (beginning-of-line))))

 (defun org-previous-visible-heading (arg)
   "Move to the previous visible heading.
@@ -20830,11 +20907,10 @@ ones already marked."
  (set-mark
  (save-excursion
    (goto-char (mark))
-   (goto-char (org-element-property :end (org-element-at-point)))
-   (point)))
+   (goto-char (org-element-property :end (org-element-at-point)))))
       (let ((element (org-element-at-point)))
  (end-of-line)
- (push-mark (min (point-max) (org-element-property :end element)) t t)
+ (push-mark (org-element-property :end element) t t)
  (goto-char (org-element-property :begin element))))))

 (defun org-narrow-to-element ()
-- 
2.17.1

[-- Attachment #2: Type: text/html, Size: 8382 bytes --]