From c59d39d76266670200f9cfe70a1e1c2dad04c8bc 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-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  | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 94 insertions(+)

diff --git a/etc/ORG-NEWS b/etc/ORG-NEWS
index b7c88fd..2c28785 100644
--- a/etc/ORG-NEWS
+++ b/etc/ORG-NEWS
@@ -169,6 +169,18 @@ official [[https://clojure.org/guides/deps_and_cli][Clojure CLI tools]].
 The command can be customized with ~ob-clojure-cli-command~.
 
 ** 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.
+
 *** Add support for ~logind~ idle time in ~org-user-idle-seconds~
 
 When Emacs is built with =dbus= support and
diff --git a/lisp/org.el b/lisp/org.el
index 26d2a86..6742449 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)
@@ -3582,6 +3583,12 @@ (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
@@ -5543,6 +5550,66 @@ (defun org-fontify-extend-region (beg end _old-len)
 	     (cons beg (or (funcall extend "end" "]" 1) end)))
 	    (t (cons beg end))))))
 
+(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)
+      (let ((el (org-element-at-point)) beg end next)
+        (pcase (org-element-type el)
+          (`src-block
+           (setq beg (org-element-property :end el)
+                 end beg
+                 next end))
+          (`headline
+           (setq beg (org-element-property :begin el)
+                 end (org-element-property :contents-begin el)
+                 next end))
+          (`paragraph
+           ;; Compute the regions of the paragraph excluding inline
+           ;; source blocks.
+           (setq beg nil end nil)
+           (let ((pbeg (org-element-property :begin el))
+                 (pend (org-element-property :end el)))
+             (goto-char pbeg)
+             (push pbeg 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)
+             (setq beg (nreverse beg)
+                   end (nreverse end)
+                   next pend)))
+          (_
+           (setq beg (or (org-element-property :contents-begin el)
+                         (org-element-property :begin el))
+                 end (or (org-element-property :contents-end el)
+                         (org-element-property :end el))
+                 next (org-element-property :end el))))
+        (cl-letf (((symbol-function #'delete-region)
+                   (lambda (beg end)
+                     (add-text-properties beg end '(invisible t))))
+                  (ansi-color-apply-face-function
+                   (lambda (beg end face)
+                     (font-lock-prepend-text-property beg end 'face face))))
+          (if (consp beg)
+              (while (consp beg)
+                (ansi-color-apply-on-region (pop beg) (pop end)))
+            (ansi-color-apply-on-region beg end)))
+        ;; Reset the context after applying the color to prevent color
+        ;; settings from propagating to other elements.  This also
+        ;; avoids issues where `ansi-color-apply-on-region' attempts
+        ;; to use an old starting point that may be from a different
+        ;; part of the buffer, leading to "wrong side of point"
+        ;; errors.
+        (setq ansi-color-context-region nil)
+        (goto-char next)))))
+
 (defun org-activate-footnote-links (limit)
   "Add text properties for footnotes."
   (let ((fn (org-footnote-next-reference-or-definition limit)))
@@ -5861,6 +5928,7 @@ (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
@@ -15455,6 +15523,20 @@ (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))
+
+(add-hook 'org-mode-hook #'org-ansi-mode)
+
 
 ;;;; CDLaTeX minor mode
 
-- 
2.39.1