From 878c1d73d048d949dbace5688929d2d7701706cd Mon Sep 17 00:00:00 2001
From: "Richard M. Stallman" <rms@gnu.org>
Date: Tue, 18 Jul 1995 21:43:16 +0000
Subject: [PATCH] (font-lock-defaults): New variable.
 (nroff-mode-syntax-table): New variable to provide comment syntax for
 font-lock; I'm not sure if this is (or should be) necessary in 19.29 with
 font-lock-defaults. (nroff-font-lock-keywords): New variable. (nroff-mode):
 Install nroff syntax table and font lock keywords. Comment about comments in
 filling and line-counting.

---
 lisp/textmodes/nroff-mode.el | 45 ++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/lisp/textmodes/nroff-mode.el b/lisp/textmodes/nroff-mode.el
index b3258f38e11..15d5fd32c24 100644
--- a/lisp/textmodes/nroff-mode.el
+++ b/lisp/textmodes/nroff-mode.el
@@ -1,6 +1,6 @@
 ;;; nroff-mode.el --- GNU Emacs major mode for editing nroff source
 
-;; Copyright (C) 1985, 1986, 1994 Free Software Foundation, Inc.
+;; Copyright (C) 1985, 1986, 1994, 1995 Free Software Foundation, Inc.
 
 ;; Maintainer: FSF
 ;; Keywords: wp
@@ -29,6 +29,9 @@
 ;; a command to count text lines (excluding nroff constructs), a command
 ;; to center a line, and movement commands that know how to skip macros.
 
+;; Paragraph filling and line-counting currently don't respect comments,
+;; as they should.
+
 ;;; Code:
 
 (defvar nroff-mode-abbrev-table nil
@@ -47,6 +50,32 @@
       (define-key nroff-mode-map "\en" 'forward-text-line)
       (define-key nroff-mode-map "\ep" 'backward-text-line)))
 
+(defvar nroff-mode-syntax-table nil
+  "Syntax table used while in nroff mode.")
+
+(defvar nroff-font-lock-keywords
+  (list
+   ;; Directives are . or ' at start of line, followed by
+   ;; optional whitespace, then command (which my be longer than
+   ;; 2 characters in groff).  Perhaps the arguments should be
+   ;; fontified as well.
+   "^[.']\\s-*\\sw+"
+   ;; There are numerous groff escapes; the following get things
+   ;; like \-, \(em (standard troff) and \f[bar] (groff
+   ;; variants).  This won't currently do groff's \A'foo' and
+   ;; the like properly.  One might expect it to highlight an escape's
+   ;; arguments in common cases, like \f.
+   (concat "\\\\"                     ; backslash
+         "\\("                        ; followed by various possibilities
+         (mapconcat 'identity
+                    '("[f*n]*\\[.+]"  ; some groff extensions
+                      "(.."           ; two chars after (
+                      "[^(\"]"        ; single char escape
+                      ) "\\|")
+         "\\)")
+   )
+  "Font-lock highlighting control in nroff-mode.")
+
 ;;;###autoload
 (defun nroff-mode ()
   "Major mode for editing text intended for nroff to format.
@@ -59,7 +88,19 @@ closing requests for requests that are used in matched pairs."
   (use-local-map nroff-mode-map)
   (setq mode-name "Nroff")
   (setq major-mode 'nroff-mode)
-  (set-syntax-table text-mode-syntax-table)
+  (if nroff-mode-syntax-table
+      ()
+    (setq nroff-mode-syntax-table (copy-syntax-table text-mode-syntax-table))
+    ;; " isn't given string quote syntax in text-mode but it
+    ;; (arguably) should be for use round nroff arguments (with ` and
+    ;; ' used otherwise).
+    (modify-syntax-entry ?\" "\"  2" nroff-mode-syntax-table)
+    ;; Comments are delimited by \" and newline.
+    (modify-syntax-entry ?\\ "\\  1" nroff-mode-syntax-table)
+    (modify-syntax-entry ?\n ">  1" nroff-mode-syntax-table))
+  (set-syntax-table nroff-mode-syntax-table)
+  (make-local-variable 'font-lock-defaults)
+  (setq font-lock-defaults '(nroff-font-lock-keywords nil t))
   (setq local-abbrev-table nroff-mode-abbrev-table)
   (make-local-variable 'nroff-electric-mode)
   (setq nroff-electric-mode nil)
-- 
2.39.2