Partial implementation of \h (horizontal line drawing function).

A full implementation would require access to output device properties
and state variables (both only available after the main parser has
finalized the parse tree) before numerical expansions in the roff
preprocessor (i.e., before the main parser is even started).

Not trying to pull that stunt right now because the static-width
implementation committed here is sufficient for tcl-style manual pages
and already more complicated than i would have suspected.

4 files changed, 80 insertions, 11 deletions

diff --git a/mandoc.c b/mandoc.c
index 2ff4e186..fc360def 100644
--- a/mandoc.c
+++ b/mandoc.c
@@ -1,7 +1,7 @@
-/*	$Id: mandoc.c,v 1.99 2017/06/01 19:05:37 schwarze Exp $ */
+/*	$Id: mandoc.c,v 1.100 2017/06/02 19:21:23 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2011-2015 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2011-2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -175,7 +175,17 @@ mandoc_escape(const char **end, const char **start, int *sz)
 				++*end;
 			return ESCAPE_ERROR;
 		}
-		gly = (*start)[-1] == 'h' ? ESCAPE_HORIZ : ESCAPE_IGNORE;
+		switch ((*start)[-1]) {
+		case 'h':
+			gly = ESCAPE_HORIZ;
+			break;
+		case 'l':
+			gly = ESCAPE_HLINE;
+			break;
+		default:
+			gly = ESCAPE_IGNORE;
+			break;
+		}
 		term = **start;
 		*start = ++*end;
 		break;
diff --git a/mandoc.h b/mandoc.h
index c15ed4d0..39a18cbd 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -1,4 +1,4 @@
-/*	$Id: mandoc.h,v 1.220 2017/06/01 19:05:37 schwarze Exp $ */
+/*	$Id: mandoc.h,v 1.221 2017/06/02 19:21:23 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -412,6 +412,7 @@ enum	mandoc_esc {
 	ESCAPE_UNICODE, /* a unicode codepoint */
 	ESCAPE_NOSPACE, /* suppress space if the last on a line */
 	ESCAPE_HORIZ, /* horizontal movement */
+	ESCAPE_HLINE, /* horizontal line drawing */
 	ESCAPE_SKIPCHAR, /* skip the next character */
 	ESCAPE_OVERSTRIKE /* overstrike all chars in the argument */
 };
diff --git a/roff.7 b/roff.7
index bfce9b16..05a2b5a4 100644
--- a/roff.7
+++ b/roff.7
@@ -1,4 +1,4 @@
-.\"	$Id: roff.7,v 1.81 2017/06/01 19:05:37 schwarze Exp $
+.\"	$Id: roff.7,v 1.82 2017/06/02 19:21:23 schwarze Exp $
 .\"
 .\" Copyright (c) 2010, 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2010,2011,2013-2015,2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -15,7 +15,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: June 1 2017 $
+.Dd $Mdocdate: June 2 2017 $
 .Dt ROFF 7
 .Os
 .Sh NAME
@@ -1939,9 +1939,11 @@ and
 .Ss \eL\(aq Ns Ar number Ns Oo Ar c Oc Ns \(aq
 Vertical line drawing function; ignored by
 .Xr mandoc 1 .
-.Ss \el\(aq Ns Ar number Ns Oo Ar c Oc Ns \(aq
-Horizontal line drawing function; ignored by
-.Xr mandoc 1 .
+.Ss \el\(aq Ns Ar width Ns Oo Ar c Oc Ns \(aq
+Draw a horizontal line of
+.Ar width
+using the glyph
+.Ar c .
 .Ss \eM[ Ns Ar name ]
 Set fill (background) color (groff extension); ignored by
 .Xr mandoc 1 .
diff --git a/term.c b/term.c
index 266c49e7..afd5951a 100644
--- a/term.c
+++ b/term.c
@@ -1,4 +1,4 @@
-/*	$Id: term.c,v 1.261 2017/06/01 19:05:37 schwarze Exp $ */
+/*	$Id: term.c,v 1.262 2017/06/02 19:21:23 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -404,7 +404,7 @@ term_word(struct termp *p, const char *word)
 	const char	 nbrsp[2] = { ASCII_NBRSP, 0 };
 	const char	*seq, *cp;
 	int		 sz, uc;
-	size_t		 ssz;
+	size_t		 csz, lsz, ssz;
 	enum mandoc_esc	 esc;
 
 	if ( ! (TERMP_NOSPACE & p->flags)) {
@@ -510,6 +510,62 @@ term_word(struct termp *p, const char *word)
 				}
 			}
 			continue;
+		case ESCAPE_HLINE:
+			if (a2roffsu(seq, &su, SCALE_EM) == 0)
+				continue;
+			uc = term_hspan(p, &su) / 24;
+			if (uc <= 0) {
+				if (p->rmargin <= p->offset)
+					continue;
+				lsz = p->rmargin - p->offset;
+			} else
+				lsz = uc;
+			while (sz &&
+			    strchr(" %&()*+-./0123456789:<=>", *seq)) {
+				seq++;
+				sz--;
+			}
+			if (sz && strchr("cifMmnPpuv", *seq)) {
+				seq++;
+				sz--;
+			}
+			if (sz == 0)
+				uc = -1;
+			else if (*seq == '\\') {
+				seq++;
+				esc = mandoc_escape(&seq, &cp, &sz);
+				switch (esc) {
+				case ESCAPE_UNICODE:
+					uc = mchars_num2uc(cp + 1, sz - 1);
+					break;
+				case ESCAPE_NUMBERED:
+					uc = mchars_num2char(cp, sz);
+					break;
+				case ESCAPE_SPECIAL:
+					uc = mchars_spec2cp(cp, sz);
+					break;
+				default:
+					uc = -1;
+					break;
+				}
+			} else
+				uc = *seq;
+			if (uc < 0x20 || (uc > 0x7E && uc < 0xA0))
+				uc = '_';
+			if (p->enc == TERMENC_ASCII) {
+				cp = ascii_uc2str(uc);
+				csz = term_strlen(p, cp);
+				ssz = strlen(cp);
+			} else
+				csz = (*p->width)(p, uc);
+			while (lsz >= csz) {
+				if (p->enc == TERMENC_ASCII)
+					encode(p, cp, ssz);
+				else
+					encode1(p, uc);
+				lsz -= csz;
+			}
+			continue;
 		case ESCAPE_SKIPCHAR:
 			p->flags |= TERMP_BACKAFTER;
 			continue;