Rudimentary implementation of the roff(7) \o escape sequence (overstrike).

This is of some relevance because the pod2man(1) preamble abuses it
for the icelandic letter Thorn, instead of simply using \(TP and \(Tp.
Missing feature found by sthen@ in DateTime::Locale::is_IS(3p).

8 files changed, 87 insertions, 19 deletions

diff --git a/regress/usr.bin/mandoc/roff/esc/Makefile b/regress/usr.bin/mandoc/roff/esc/Makefile
index 92db491a430..ab2b01a543c 100644
--- a/regress/usr.bin/mandoc/roff/esc/Makefile
+++ b/regress/usr.bin/mandoc/roff/esc/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.9 2015/01/01 18:10:09 schwarze Exp $
+# $OpenBSD: Makefile,v 1.10 2015/01/21 20:20:49 schwarze Exp $
 
-REGRESS_TARGETS = one two multi B c c_man e f h w z ignore
+REGRESS_TARGETS = one two multi B c c_man e f h o w z ignore
 LINT_TARGETS	= B h w ignore
 
 # Postprocessing to remove "character backspace" sequences
diff --git a/regress/usr.bin/mandoc/roff/esc/o.in b/regress/usr.bin/mandoc/roff/esc/o.in
new file mode 100644
index 00000000000..2976a9d8288
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/esc/o.in
@@ -0,0 +1,18 @@
+.Dd January 21, 2015
+.Dt ESC-O 1
+.Os OpenBSD
+.Sh NAME
+.Nm esc-o
+.Nd the roff escape o sequence: overstrike
+.Sh DESCRIPTION
+empty: x\o''x
+.br
+one character: x\o'|'x
+.br
+wide/narrow: x\o'O|'x
+.br
+narrow/wide: x\o'|O'x
+.br
+wide/narrow/narrow: x\o'O-|'x
+.br
+narrow/narrow/wide: x\o'|-O'x
diff --git a/regress/usr.bin/mandoc/roff/esc/o.out_ascii b/regress/usr.bin/mandoc/roff/esc/o.out_ascii
new file mode 100644
index 00000000000..39dc1b1c073
--- /dev/null
+++ b/regress/usr.bin/mandoc/roff/esc/o.out_ascii
@@ -0,0 +1,14 @@
+ESC-O(1)                    General Commands Manual                   ESC-O(1)
+
+NNAAMMEE
+     eesscc--oo - the roff escape o sequence: overstrike
+
+DDEESSCCRRIIPPTTIIOONN
+     empty: xx
+     one character: x|x
+     wide/narrow: xO|x
+     narrow/wide: x|Ox
+     wide/narrow/narrow: xO-|x
+     narrow/narrow/wide: x|-Ox
+
+OpenBSD                        January 21, 2015                        OpenBSD
diff --git a/share/man/man7/roff.7 b/share/man/man7/roff.7
index 3930005a9ff..f6399c62479 100644
--- a/share/man/man7/roff.7
+++ b/share/man/man7/roff.7
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: roff.7,v 1.43 2015/01/20 22:34:15 jmc Exp $
+.\"	$OpenBSD: roff.7,v 1.44 2015/01/21 20:20:49 schwarze Exp $
 .\"
 .\" Copyright (c) 2010, 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2010, 2011, 2013, 2014 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: January 20 2015 $
+.Dd $Mdocdate: January 21 2015 $
 .Dt ROFF 7
 .Os
 .Sh NAME
@@ -1946,10 +1946,11 @@ For short names, there are variants
 and
 .No \en( Ns Ar cc .
 .Ss \eo\(aq Ns Ar string Ns \(aq
-Overstrike
-.Ar string ;
-ignored by
-.Xr mandoc 1 .
+Overstrike, that is, write all the characters contained in the
+.Ar string
+to the same output position.
+In terminal and HTML output modes,
+only the last one of the characters is visible.
 .Ss \eR\(aq Ns Ar name Oo +|- Oc Ns Ar number Ns \(aq
 Set number register; ignored by
 .Xr mandoc 1 .
diff --git a/usr.bin/mandoc/html.c b/usr.bin/mandoc/html.c
index 69f907ff526..44933c30fae 100644
--- a/usr.bin/mandoc/html.c
+++ b/usr.bin/mandoc/html.c
@@ -1,7 +1,7 @@
-/*	$OpenBSD: html.c,v 1.54 2014/12/20 00:19:54 schwarze Exp $ */
+/*	$OpenBSD: html.c,v 1.55 2015/01/21 20:20:49 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2011, 2012, 2013, 2014 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2011-2015 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
@@ -305,6 +305,8 @@ html_strlen(const char *cp)
 		case ESCAPE_NUMBERED:
 			/* FALLTHROUGH */
 		case ESCAPE_SPECIAL:
+			/* FALLTHROUGH */
+		case ESCAPE_OVERSTRIKE:
 			if (skip)
 				skip = 0;
 			else
@@ -431,6 +433,11 @@ print_encode(struct html *h, const char *p, int norecurse)
 			if ('\0' == *p)
 				nospace = 1;
 			continue;
+		case ESCAPE_OVERSTRIKE:
+			if (len == 0)
+				continue;
+			c = seq[len - 1];
+			break;
 		default:
 			continue;
 		}
diff --git a/usr.bin/mandoc/mandoc.c b/usr.bin/mandoc/mandoc.c
index 362edb9a724..14fd071dbd3 100644
--- a/usr.bin/mandoc/mandoc.c
+++ b/usr.bin/mandoc/mandoc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mandoc.c,v 1.58 2015/01/01 18:10:09 schwarze Exp $ */
+/*	$OpenBSD: mandoc.c,v 1.59 2015/01/21 20:20:49 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2011-2015 Ingo Schwarze <schwarze@openbsd.org>
@@ -154,16 +154,18 @@ mandoc_escape(const char **end, const char **start, int *sz)
 		/* FALLTHROUGH */
 	case 'D':
 		/* FALLTHROUGH */
-	case 'o':
-		/* FALLTHROUGH */
 	case 'R':
 		/* FALLTHROUGH */
 	case 'X':
 		/* FALLTHROUGH */
 	case 'Z':
-		if ('\0' == **start)
-			return(ESCAPE_ERROR);
 		gly = ESCAPE_IGNORE;
+		/* FALLTHROUGH */
+	case 'o':
+		if (**start == '\0')
+			return(ESCAPE_ERROR);
+		if (gly == ESCAPE_ERROR)
+			gly = ESCAPE_OVERSTRIKE;
 		term = **start;
 		*start = ++*end;
 		break;
diff --git a/usr.bin/mandoc/mandoc.h b/usr.bin/mandoc/mandoc.h
index 713bafd7d01..fb255d083af 100644
--- a/usr.bin/mandoc/mandoc.h
+++ b/usr.bin/mandoc/mandoc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mandoc.h,v 1.125 2015/01/20 21:12:46 schwarze Exp $ */
+/*	$OpenBSD: mandoc.h,v 1.126 2015/01/21 20:20:49 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015 Ingo Schwarze <schwarze@openbsd.org>
@@ -399,7 +399,8 @@ enum	mandoc_esc {
 	ESCAPE_NUMBERED, /* a numbered glyph */
 	ESCAPE_UNICODE, /* a unicode codepoint */
 	ESCAPE_NOSPACE, /* suppress space if the last on a line */
-	ESCAPE_SKIPCHAR /* skip the next character */
+	ESCAPE_SKIPCHAR, /* skip the next character */
+	ESCAPE_OVERSTRIKE /* overstrike all chars in the argument */
 };
 
 typedef	void	(*mandocmsg)(enum mandocerr, enum mandoclevel,
diff --git a/usr.bin/mandoc/term.c b/usr.bin/mandoc/term.c
index ee247461963..74401b36739 100644
--- a/usr.bin/mandoc/term.c
+++ b/usr.bin/mandoc/term.c
@@ -1,7 +1,7 @@
-/*	$OpenBSD: term.c,v 1.102 2014/12/24 23:31:59 schwarze Exp $ */
+/*	$OpenBSD: term.c,v 1.103 2015/01/21 20:20:49 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2010-2014 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2010-2015 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
@@ -493,6 +493,17 @@ term_word(struct termp *p, const char *word)
 		case ESCAPE_SKIPCHAR:
 			p->flags |= TERMP_SKIPCHAR;
 			continue;
+		case ESCAPE_OVERSTRIKE:
+			cp = seq + sz;
+			while (seq < cp) {
+				if (*seq == '\\') {
+					mandoc_escape(&seq, NULL, NULL);
+					continue;
+				}
+				encode1(p, *seq++);
+				if (seq < cp)
+					encode(p, "\b", 1);
+			}
 		default:
 			continue;
 		}
@@ -714,6 +725,20 @@ term_strlen(const struct termp *p, const char *cp)
 			case ESCAPE_SKIPCHAR:
 				skip = 1;
 				continue;
+			case ESCAPE_OVERSTRIKE:
+				rsz = 0;
+				rhs = seq + ssz;
+				while (seq < rhs) {
+					if (*seq == '\\') {
+						mandoc_escape(&seq, NULL, NULL);
+						continue;
+					}
+					i = (*p->width)(p, *seq++);
+					if (rsz < i)
+						rsz = i;
+				}
+				sz += rsz;
+				continue;
 			default:
 				continue;
 			}