Split tagging into a validation part including prioritization

in tag.{h,c} and {mdoc,man}_validate.c
and into a formatting part including command line argument checking
in term_tag.{h,c}, html.c, and {mdoc|man}_{term|html}.c.

Immediate functional benefits include:
* Improved prioritization of automatic tags for .Em and .Sy.
* Avoiding bogus automatic tags when .Em, .Fn, or .Sy are explicitly tagged.
* Explicit tagging of .Er and .Fl now works in HTML output.
* Automatic tagging of .IP and .TP now works in HTML output.
But mainly, this patch provides clean earth to build further improvements on.

Technical changes:
* Main program: Write a tag file for ASCII and UTF-8 output only.
* All formatters: There is no more need to delay writing the tags.
* mdoc(7)+man(7) formatters: No more need for elaborate syntax tree inspection.
* HTML formatter: If available, use the "string" attribute as the tag.
* HTML formatter: New function to write permalinks, to reduce code duplication.

Style cleanup in the vicinity while here:
* mdoc(7) terminal formatter: To set up bold font for children,
defer to termp_bold_pre() rather than calling term_fontpush() manually.
* mdoc(7) terminal formatter: Garbage collect some duplicate functions.
* mdoc(7) HTML formatter: Unify <code> handling, delete redundant functions.
* Where possible, use switch statements rather than if cascades.
* Get rid of some more Yoda notation.

The necessity for such changes was first discussed with kn@, but i didn't
bother him with a request to review the resulting -673/+782 line patch.

1 files changed, 7 insertions, 9 deletions

diff --git a/usr.bin/mandoc/man_html.c b/usr.bin/mandoc/man_html.c
index 589b4114138..dd360649d6d 100644
--- a/usr.bin/mandoc/man_html.c
+++ b/usr.bin/mandoc/man_html.c
@@ -1,7 +1,7 @@
-/*	$OpenBSD: man_html.c,v 1.129 2020/02/27 01:25:57 schwarze Exp $ */
+/* $OpenBSD: man_html.c,v 1.130 2020/03/13 00:31:05 schwarze Exp $ */
 /*
- * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2013-2015, 2017-2020 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -14,6 +14,8 @@
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * HTML formatter for man(7) used by mandoc(1).
  */
 #include <sys/types.h>
 
@@ -308,7 +310,6 @@ static int
 man_SH_pre(MAN_ARGS)
 {
 	const char	*class;
-	char		*id;
 	enum htmltag	 tag;
 
 	if (n->tok == MAN_SH) {
@@ -324,10 +325,8 @@ man_SH_pre(MAN_ARGS)
 		print_otag(h, TAG_SECTION, "c", class);
 		break;
 	case ROFFT_HEAD:
-		id = html_make_id(n, 1);
-		print_otag(h, tag, "ci", class, id);
-		if (id != NULL)
-			print_otag(h, TAG_A, "chR", "permalink", id);
+		n->flags |= NODE_ID;
+		print_otag_id(h, tag, class, n);
 		break;
 	case ROFFT_BODY:
 		break;
@@ -487,7 +486,7 @@ man_IP_pre(MAN_ARGS)
 	case ROFFT_HEAD:
 		if (body_elem == TAG_LI)
 			return 0;
-		print_otag(h, TAG_DT, "");
+		print_otag_id(h, TAG_DT, NULL, n);
 		break;
 	case ROFFT_BODY:
 		print_otag(h, body_elem, "");
@@ -495,7 +494,6 @@ man_IP_pre(MAN_ARGS)
 	default:
 		abort();
 	}
-
 	switch(n->tok) {
 	case MAN_IP:  /* Only print the first header element. */
 		if (n->child != NULL)