From 66baf6e1d435974fb4c51cc47eb5b3ace3feb22c Mon Sep 17 00:00:00 2001
From: Nathaniel Nicandro <nathanielnicandro@gmail.com>
Date: Tue, 9 May 2023 19:58:11 -0500
Subject: [PATCH] Highlight ANSI escape sequences

* etc/ORG-NEWS: Describe the new feature.
* org.el (org-fontify-ansi-sequences): New customization variable and
function which does the work of fontifying the sequences.
(org-ansi-highlightable-elements)
(org-ansi-highlightable-objects): New customization variables.
(org-ansi-new-context, org-ansi-process-region)
(org-ansi-process-block, org-ansi-process-paragraph)
(org-ansi-process-fixed-width)
(org-fontify-ansi-sequences-1): New functions.
(org-set-font-lock-defaults): Add the `org-fontify-ansi-sequences`
function to the font-lock keywords.
(org-ansi-mode): New minor mode to enable/disable highlighting of the
sequences.  Enabled in Org buffers by default.
---
 etc/ORG-NEWS |  12 +++
 lisp/org.el  | 236 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 248 insertions(+)

diff --git a/etc/ORG-NEWS b/etc/ORG-NEWS
index 1207d6f..76a81e3 100644
--- a/etc/ORG-NEWS
+++ b/etc/ORG-NEWS
@@ -492,6 +492,18 @@ Currently implemented options are:
   iCalendar programs support this usage.
 
 ** New features
+*** ANSI escape sequences are now highlighted in the whole buffer
+
+A new customization ~org-fontify-ansi-sequences~ is available which
+tells Org to highlight all ANSI sequences in the buffer if non-nil and
+the new minor mode ~org-ansi-mode~ is enabled.
+
+To disable highlighting of the sequences you can either
+disable ~org-ansi-mode~ or set ~org-fontify-ansi-sequences~ to ~nil~
+and =M-x org-mode-restart RET=.  Doing the latter will disable
+highlighting of sequences in all newly opened Org buffers whereas
+doing the former disables highlighting locally to the current buffer.
+
 *** =ob-plantuml.el=: Support tikz file format output
 
 =ob-plantuml.el= now output =tikz= :file format via
diff --git a/lisp/org.el b/lisp/org.el
index d2cd0b9..64a853c 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -81,6 +81,7 @@ (eval-when-compile (require 'gnus-sum))
 (require 'calendar)
 (require 'find-func)
 (require 'format-spec)
+(require 'ansi-color)
 
 (condition-case nil
     (load (concat (file-name-directory load-file-name)
@@ -3608,6 +3609,12 @@ (defcustom org-fontify-whole-block-delimiter-line t
   :group 'org-appearance
   :type 'boolean)
 
+(defcustom org-fontify-ansi-sequences t
+  "Non-nil means to highlight ANSI escape sequences."
+  :group 'org-appearance
+  :type 'boolean
+  :package-version '(Org . "9.7"))
+
 (defcustom org-highlight-latex-and-related nil
   "Non-nil means highlight LaTeX related syntax in the buffer.
 When non-nil, the value should be a list containing any of the
@@ -5598,6 +5605,208 @@ (defun org-fontify-extend-region (beg end _old-len)
 	     (cons beg (or (funcall extend "end" "]" 1) end)))
 	    (t (cons beg end))))))
 
+(defcustom org-ansi-highlightable-elements
+  '(plain-list drawer
+    example-block export-block fixed-width paragraph)
+  "A list of element types that will have ANSI sequences processed."
+  :type '(list (symbol :tag "Element Type"))
+  :version "9.7"
+  :group 'org-appearance)
+
+(defcustom org-ansi-highlightable-objects
+  '(bold code export-snippet italic macro
+    strike-through table-cell underline verbatim)
+  "A list of object types that will have ANSI sequences processed."
+  :type '(list (symbol :tag "Object Type"))
+  :version "9.7"
+  :group 'org-appearance)
+
+(defun org-ansi-new-context (pos)
+  (list (list (make-bool-vector 8 nil)
+              nil nil)
+        (copy-marker pos)))
+
+(defun org-ansi-process-region (beg end &optional context)
+  (or context (setq context (org-ansi-new-context beg)))
+  (move-marker (cadr context) beg)
+  (let ((ansi-color-context-region context)
+        (ansi-color-apply-face-function
+         (lambda (beg end face)
+           (font-lock-prepend-text-property beg end 'face face))))
+    (ansi-color-apply-on-region beg end t)))
+
+(defun org-ansi-process-block (el &optional context)
+  (let ((beg (org-element-property :begin el))
+        (end (org-element-property :end el)))
+    (save-excursion
+      (goto-char beg)
+      (while (org-at-keyword-p)
+        (forward-line))
+      (setq beg (line-beginning-position 2)))
+    (save-excursion
+      (goto-char end)
+      (skip-chars-backward " \t\n")
+      (setq end (line-beginning-position)))
+    (org-ansi-process-region beg end context)))
+
+(defun org-ansi-process-paragraph (el &optional context)
+  ;; Compute the regions of the paragraph excluding inline
+  ;; source blocks.
+  (let ((pend (org-element-property :contents-end el)) beg end)
+    (push (point) beg)
+    (while (re-search-forward
+            "\\<src_\\([^ \t\n[{]+\\)[{[]" pend t)
+      (let ((el (org-element-context)))
+        (when (eq (org-element-type el) 'inline-src-block)
+          (push (org-element-property :begin el) end)
+          (goto-char (org-element-property :end el))
+          (push (point) beg))))
+    (push pend end)
+    (let ((ansi-context (or context (org-ansi-new-context (point)))))
+      (while beg
+        (org-ansi-process-region (pop beg) (pop end) ansi-context)))))
+
+(defun org-ansi-process-fixed-width (el &optional context)
+  (org-ansi-process-region
+   (org-element-property :begin el)
+   (save-excursion
+     (goto-char (org-element-property :end el))
+     (skip-chars-backward " \t\n")
+     (point))
+   context))
+
+(defun org-fontify-ansi-sequences-1 (limit &optional ansi-context)
+  (let ((skip-to-end-p
+         (lambda (el)
+           (or (null (org-element-property :contents-begin el))
+               (<= (org-element-property :contents-end el)
+                   (point)
+                   (org-element-property :end el))))))
+    (while (< (point) limit)
+      (let* ((el (org-element-at-point))
+             (type (org-element-type el)))
+        (pcase type
+          ;; Greater elements
+          ((or `headline `inlinetask `item
+               `center-block `quote-block `special-block
+               `drawer)
+           (if (funcall skip-to-end-p el)
+               (goto-char (org-element-property :end el))
+             (goto-char (org-element-property :contents-begin el))))
+          ((or `dynamic-block `footnote-definition `property-drawer)
+           (goto-char (org-element-property :end el)))
+          (`plain-list
+           (let ((end (org-element-property :end el)))
+             (goto-char (org-element-property :contents-begin el))
+             (while (< (point) end)
+               ;; Move to within the first item of a list.
+               (forward-char)
+               (let* ((item (org-element-at-point))
+                      (cbeg (org-element-property :contents-begin item)))
+                 (when cbeg
+                   (goto-char cbeg)
+                   (org-fontify-ansi-sequences-1
+                    (org-element-property :contents-end item)
+                    ansi-context))
+                 (goto-char (org-element-property :end item))
+                 (skip-chars-forward " \t\n")))))
+          (`table
+           (if (funcall skip-to-end-p el)
+               (goto-char (org-element-property :end el))
+             (goto-char (org-element-property :contents-begin el))
+             ;; Move to within the table-row of a table to continue
+             ;; processing it.
+             (forward-char)))
+          ;; Lesser elements
+          (`table-row
+           (if (eq (org-element-property :type el) 'rule)
+               (goto-char (org-element-property :end el))
+             (let ((end-1 (1- (org-element-property :end el))))
+               (goto-char (org-element-property :contents-begin el))
+               (while (< (point) end-1)
+                 (let ((cell (org-element-context)))
+                   (org-ansi-process-region
+                    (org-element-property :contents-begin cell)
+                    (org-element-property :contents-end cell)
+                    ansi-context)
+                   (goto-char (org-element-property :end cell))))
+               (forward-char))))
+          ((or `example-block `export-block)
+           (org-ansi-process-block el ansi-context)
+           (goto-char (org-element-property :end el)))
+          (`fixed-width
+           (org-ansi-process-fixed-width el ansi-context)
+           (goto-char (org-element-property :end el)))
+          (`paragraph
+           (org-ansi-process-paragraph el ansi-context)
+           (goto-char (org-element-property :end el)))
+          (_
+           (goto-char (org-element-property :end el))))))))
+
+(defvar org-ansi-mode)
+
+(defun org-fontify-ansi-sequences (limit)
+  "Fontify ANSI sequences."
+  (when (and org-fontify-ansi-sequences org-ansi-mode)
+    (while (< (point) limit)
+      (if (re-search-forward ansi-color-control-seq-regexp limit t)
+          (let* ((ctx (progn
+                        (goto-char (match-beginning 0))
+                        (org-element-context)))
+                 (type (org-element-type ctx)))
+            (cond
+             ((memq type org-ansi-highlightable-objects)
+              ;; If the element-context is an object then there has not
+              ;; been a sequence at the element level so limit the
+              ;; effect of the sequence to the object.
+              (org-ansi-process-region
+               (point)
+               (or (org-element-property :contents-end ctx)
+                   (- (org-element-property :end ctx)
+                      (org-element-property :post-blank ctx)
+                      1))
+               (org-ansi-new-context (point)))
+              (goto-char (org-element-property :end ctx)))
+             ((memq type org-ansi-highlightable-elements)
+              (let ((el ctx))
+                (while (and el (not (org-element-property :results el)))
+                  (setq el (org-element-property :parent el)))
+                (if (and el (not (eq el ctx)))
+                    ;; If the element-context is a highlightable element
+                    ;; that has an ancestor with a RESULTS affiliated
+                    ;; keyword, process the full greater element with
+                    ;; that keyword.
+                    (if (not (memq (org-element-type el) org-ansi-highlightable-elements))
+                        ;; Skip over the greater element if not
+                        ;; highlightable.
+                        (goto-char (org-element-property :end el))
+                      (goto-char (org-element-property :begin el))
+                      (org-fontify-ansi-sequences-1
+                       (or (org-element-property :contents-end el)
+                           (org-element-property :end el))
+                       (org-ansi-new-context (point)))
+                      (goto-char (org-element-property :end el)))
+                  ;; If the element-context is not a part of a greater
+                  ;; element with a RESULTS affiliated keyword, then it
+                  ;; is just a highlightable lesser element.  Process
+                  ;; the element.
+                  (pcase type
+                    ((or `example-block `export-block)
+                     (org-ansi-process-block ctx))
+                    (`fixed-width
+                     (org-ansi-process-fixed-width ctx))
+                    (`paragraph
+                     (org-ansi-process-paragraph ctx)))
+                  (goto-char (org-element-property :end ctx)))))
+             (t
+              (pcase type
+                ((or `headline `inlinetask)
+                 (goto-char (or (org-element-property :contents-begin ctx)
+                                (org-element-property :end ctx))))
+                (_
+                 (goto-char (org-element-property :end ctx)))))))
+        (goto-char limit)))))
+
 (defun org-activate-footnote-links (limit)
   "Add text properties for footnotes."
   (let ((fn (org-footnote-next-reference-or-definition limit)))
@@ -5915,6 +6124,7 @@ (defun org-set-font-lock-defaults ()
 	  ;; Blocks and meta lines
 	  '(org-fontify-meta-lines-and-blocks)
           '(org-fontify-inline-src-blocks)
+          '(org-fontify-ansi-sequences)
           ;; Citations.  When an activate processor is specified, if
           ;; specified, try loading it beforehand.
           (progn
@@ -15582,6 +15792,32 @@ (defun org-agenda-prepare-buffers (files)
     (when org-agenda-file-menu-enabled
       (org-install-agenda-files-menu))))
 
+
+;;;; ANSI minor mode
+
+(define-minor-mode org-ansi-mode
+  "Toggle the minor `org-ansi-mode'.
+This mode adds support to highlight ANSI sequences in Org mode.
+The sequences are highlighted only if the customization
+`org-fontify-ansi-sequences' is non-nil when the mode is enabled.
+\\{org-ansi-mode-map}"
+  :lighter " OANSI"
+  (org-restart-font-lock)
+  (unless org-ansi-mode
+    (org-with-wide-buffer
+     (goto-char (point-min))
+     (while (re-search-forward ansi-color-control-seq-regexp nil t)
+       (let ((beg (match-beginning 0))
+             (end (point)))
+         (dolist (ov (overlays-at beg))
+           (when (and (= beg (overlay-start ov))
+                      (= end (overlay-end ov))
+                      (plist-get (overlay-properties ov) 'invisible))
+             ;; Assume this is the overlay added by `ansi-color-apply-on-region'
+             (delete-overlay ov))))))))
+
+(add-hook 'org-mode-hook #'org-ansi-mode)
+
 
 ;;;; CDLaTeX minor mode
 
-- 
2.39.1