From be7d65efa1ca204f4aa78c054f25f612769eacee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Fri, 10 Jun 2022 23:43:19 +0200
Subject: Add xroff.el.

---
 xroff.el | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 xroff.el

diff --git a/xroff.el b/xroff.el
new file mode 100644
index 0000000..8c3ecc2
--- /dev/null
+++ b/xroff.el
@@ -0,0 +1,49 @@
+(defvar xroff--request-regexp
+  (rx "<"
+	 (group (+ (or "\\>"
+		       (not (in "> ")))))
+	 (group (* (or "\\>"
+		       (not ?>))))
+	 ">"))
+
+(defconst xroff-font-lock-keywords
+  `(("<!--.*-->"
+     (0 font-lock-comment-face))
+    ("\\\\\\(.\\)"
+     (1 font-lock-builtin-face))
+    (,(concat xroff--request-regexp)
+     (1 font-lock-keyword-face)
+     (2 font-lock-string-face))
+    (,(concat "\\\\" xroff--request-regexp)
+     (1 nil t)
+     (2 nil t))
+    ;; ("<FS\\(?: \\(?:\\\\>\\|[^>]\\)*\\)?>\\(.*?\\)<FE\\(?: \\(?:\\\\>\\|[^>]\\)*\\)?>"
+    ;;  1 font-lock-doc-string)
+    ))
+
+(define-derived-mode xroff-mode text-mode "Xroff"
+  "Major mode for editing documents with xroff syntax."
+  ;; A start or end tag by itself on a line separates a paragraph.
+  ;; This is desirable because SGML discards a newline that appears
+  ;; immediately after a start tag or immediately before an end tag.
+  (setq-local paragraph-start (concat "[ \t]*$\\|\
+\[ \t]*</?\\(" sgml-name-re sgml-attrs-re "\\)?>"))
+  (setq-local paragraph-separate (concat paragraph-start "$"))
+  (setq-local adaptive-fill-regexp "[ \t]*")
+  (add-hook 'fill-nobreak-predicate 'sgml-fill-nobreak nil t)
+  (setq-local indent-line-function 'sgml-indent-line)
+  (setq-local comment-start "<!-- ")
+  (setq-local comment-end " -->")
+  (setq-local comment-indent-function 'sgml-comment-indent)
+  (setq-local comment-line-break-function 'sgml-comment-indent-new-line)
+  (setq-local skeleton-further-elements '((completion-ignore-case t)))
+  (setq-local skeleton-end-hook
+	      (lambda ()
+		(or (eolp)
+		    (not (or (eq v2 '\n) (eq (car-safe v2) '\n)))
+		    (newline-and-indent))))
+  (setq-local font-lock-defaults '((xroff-font-lock-keywords) nil t nil))
+  ;; (setq-local font-lock-multiline t)
+  (setq-local comment-start-skip "<!--[ \t]*")
+  (setq-local comment-end-skip "[ \t]*--[ \t\n]*>")
+  (visual-line-mode 1))
-- 
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