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).

6 files changed, 61 insertions, 24 deletions

diff --git a/html.c b/html.c
index da980857..487dacda 100644
--- a/html.c
+++ b/html.c
@@ -1,7 +1,7 @@
-/*	$Id: html.c,v 1.184 2014/12/20 00:20:11 schwarze Exp $ */
+/*	$Id: html.c,v 1.185 2015/01/21 20:33:25 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
@@ -307,6 +307,8 @@ html_strlen(const char *cp)
 		case ESCAPE_NUMBERED:
 			/* FALLTHROUGH */
 		case ESCAPE_SPECIAL:
+			/* FALLTHROUGH */
+		case ESCAPE_OVERSTRIKE:
 			if (skip)
 				skip = 0;
 			else
@@ -433,6 +435,11 @@ 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/mandoc.c b/mandoc.c
index 4975df00..a61d2331 100644
--- a/mandoc.c
+++ b/mandoc.c
@@ -1,4 +1,4 @@
-/*	$Id: mandoc.c,v 1.90 2015/01/01 18:11:45 schwarze Exp $ */
+/*	$Id: mandoc.c,v 1.91 2015/01/21 20:33:25 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2011-2015 Ingo Schwarze <schwarze@openbsd.org>
@@ -156,16 +156,18 @@ 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/mandoc.h b/mandoc.h
index 8c3c8749..9cbc0ff0 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -1,4 +1,4 @@
-/*	$Id: mandoc.h,v 1.183 2015/01/20 21:16:51 schwarze Exp $ */
+/*	$Id: mandoc.h,v 1.184 2015/01/21 20:33:25 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/mandoc_escape.3 b/mandoc_escape.3
index f381b629..fec298b8 100644
--- a/mandoc_escape.3
+++ b/mandoc_escape.3
@@ -1,4 +1,4 @@
-.\"	$Id: mandoc_escape.3,v 1.2 2014/10/28 14:06:31 schwarze Exp $
+.\"	$Id: mandoc_escape.3,v 1.3 2015/01/21 20:33:25 schwarze Exp $
 .\"
 .\" Copyright (c) 2014 Ingo Schwarze <schwarze@openbsd.org>
 .\"
@@ -14,14 +14,12 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: October 28 2014 $
+.Dd $Mdocdate: January 21 2015 $
 .Dt MANDOC_ESCAPE 3
 .Os
 .Sh NAME
 .Nm mandoc_escape
 .Nd parse roff escape sequences
-.Sh LIBRARY
-.Lb libmandoc
 .Sh SYNOPSIS
 .In sys/types.h
 .In mandoc.h
@@ -119,8 +117,8 @@ in turn contain other escape sequences,
 for error detection internally by the
 .Xr roff 7
 parser part of the
-.Lb libmandoc ,
-see the file
+.Xr mandoc 3
+library, see the file
 .Pa roff.c ,
 .It
 above all externally by the
@@ -256,6 +254,10 @@ Such ASCII character escape sequences can be rendered using the function
 described in the
 .Xr mchars_alloc 3
 manual.
+.It Dv ESCAPE_OVERSTRIKE
+The escape sequence
+.Ic \eo
+followed by an argument delimited by an arbitrary character.
 .It Dv ESCAPE_IGNORE
 .Bl -bullet -width 2n
 .It
@@ -288,7 +290,6 @@ The escape sequences
 .Ic \eA ,
 .Ic \eb ,
 .Ic \eD ,
-.Ic \eo ,
 .Ic \eR ,
 .Ic \eX ,
 and
diff --git a/roff.7 b/roff.7
index 2c1b98f6..c8c37cc0 100644
--- a/roff.7
+++ b/roff.7
@@ -1,4 +1,4 @@
-.\"	$Id: roff.7,v 1.64 2015/01/20 22:45:07 schwarze Exp $
+.\"	$Id: roff.7,v 1.65 2015/01/21 20:33:25 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
@@ -1948,10 +1948,11 @@ 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/term.c b/term.c
index e6e3f641..7ce90bcb 100644
--- a/term.c
+++ b/term.c
@@ -1,7 +1,7 @@
-/*	$Id: term.c,v 1.242 2014/12/24 23:32:42 schwarze Exp $ */
+/*	$Id: term.c,v 1.243 2015/01/21 20:33:25 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
@@ -495,6 +495,17 @@ 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;
 		}
@@ -716,6 +727,20 @@ 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;
 			}