Naive implementation of the roff(7) .po (page offset) request.

This clearly works when .po is called on the top level, but might
not be sophisticated enough if people call .po inside indentation-changing
contexts, but i haven't seen that in manual pages (yet :).

11 files changed, 91 insertions, 15 deletions

diff --git a/mdoc_man.c b/mdoc_man.c
index 65916cf4..cf552ce9 100644
--- a/mdoc_man.c
+++ b/mdoc_man.c
@@ -1,4 +1,4 @@
-/*	$Id: mdoc_man.c,v 1.121 2017/06/14 13:00:31 schwarze Exp $ */
+/*	$Id: mdoc_man.c,v 1.122 2017/06/14 22:51:25 schwarze Exp $ */
 /*
  * Copyright (c) 2011-2017 Ingo Schwarze <schwarze@openbsd.org>
  *
@@ -130,6 +130,7 @@ static	const void_fp roff_manacts[ROFF_MAX] = {
 	pre_ft,		/* ft */
 	pre_onearg,	/* ll */
 	pre_onearg,	/* mc */
+	pre_onearg,	/* po */
 	pre_onearg,	/* rj */
 	pre_sp,		/* sp */
 	pre_ta,		/* ta */
diff --git a/regress/roff/Makefile b/regress/roff/Makefile
index 0a464197..dae2ac37 100644
--- a/regress/roff/Makefile
+++ b/regress/roff/Makefile
@@ -1,7 +1,7 @@
 # $OpenBSD: Makefile,v 1.20 2015/02/06 16:05:51 schwarze Exp $
 
 SUBDIR  = args cond esc scale string
-SUBDIR += br cc de ds ft ig it ll na nr ps rm sp ta ti tr
+SUBDIR += br cc de ds ft ig it ll na nr po ps rm sp ta ti tr
 
 .include "../Makefile.sub"
 .include <bsd.subdir.mk>
diff --git a/regress/roff/po/Makefile b/regress/roff/po/Makefile
new file mode 100644
index 00000000..dabc7c9e
--- /dev/null
+++ b/regress/roff/po/Makefile
@@ -0,0 +1,5 @@
+# $OpenBSD: Makefile,v 1.1 2017/05/08 15:33:43 schwarze Exp $
+
+REGRESS_TARGETS	= basic-mdoc
+
+.include <bsd.regress.mk>
diff --git a/regress/roff/po/basic-mdoc.in b/regress/roff/po/basic-mdoc.in
new file mode 100644
index 00000000..082be68c
--- /dev/null
+++ b/regress/roff/po/basic-mdoc.in
@@ -0,0 +1,20 @@
+.Dd June 14, 2017
+.Dt PO-BASIC-MDOC 1
+.Os OpenBSD
+.Sh NAME
+.Nm po-basic-mdoc
+.Nd the roff page offset request
+.Sh DESCRIPTION
+initial text
+.Pp
+.po -2n
+shifted left
+.Pp
+.po +5n
+shifted right
+.Pp
+.po XXX
+shifted left
+.Pp
+.po 0
+final text
diff --git a/regress/roff/po/basic-mdoc.out_ascii b/regress/roff/po/basic-mdoc.out_ascii
new file mode 100644
index 00000000..0b35c2bd
--- /dev/null
+++ b/regress/roff/po/basic-mdoc.out_ascii
@@ -0,0 +1,17 @@
+PO-BASIC-MDOC(1)            General Commands Manual           PO-BASIC-MDOC(1)
+
+NNAAMMEE
+     ppoo--bbaassiicc--mmddoocc - the roff page offset request
+
+DDEESSCCRRIIPPTTIIOONN
+     initial text
+
+   shifted left
+
+        shifted right
+
+   shifted left
+
+     final text
+
+OpenBSD                          June 14, 2017                         OpenBSD
diff --git a/roff.7 b/roff.7
index 31bfcf42..1445b525 100644
--- a/roff.7
+++ b/roff.7
@@ -1,4 +1,4 @@
-.\"	$Id: roff.7,v 1.91 2017/06/14 19:39:18 schwarze Exp $
+.\"	$Id: roff.7,v 1.92 2017/06/14 22:51:25 schwarze Exp $
 .\"
 .\" Copyright (c) 2010, 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2010,2011,2013-2015,2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -1441,8 +1441,15 @@ Currently ignored.
 Print all number registers on standard error output.
 Currently ignored.
 .It Ic \&po Op Oo Cm + Ns | Ns Cm - Oc Ns Ar offset
-Set horizontal page offset.
-Currently ignored.
+Set a horizontal page offset.
+If no argument is specified, the page offset is reverted to its
+previous value.
+If a sign is specified, the new page offset is calculated relative
+to the current one; otherwise, it is absolute.
+The argument follows the syntax of
+.Sx Scaling Widths
+and the default scaling unit is
+.Cm m .
 .It Ic \&ps Op Oo Cm + Ns | Ns Cm - Oc Ns size
 Change point size.
 Currently ignored.
diff --git a/roff.c b/roff.c
index 8224639a..1577a9b8 100644
--- a/roff.c
+++ b/roff.c
@@ -1,4 +1,4 @@
-/*	$Id: roff.c,v 1.311 2017/06/14 19:39:18 schwarze Exp $ */
+/*	$Id: roff.c,v 1.312 2017/06/14 22:51:25 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -223,8 +223,8 @@ static	enum rofferr	 roff_userdef(ROFF_ARGS);
 
 const char *__roff_name[MAN_MAX + 1] = {
 	"br",		"ce",		"ft",		"ll",
-	"mc",		"rj",		"sp",		"ta",
-	"ti",		NULL,
+	"mc",		"po",		"rj",		"sp",
+	"ta",		"ti",		NULL,
 	"ab",		"ad",		"af",		"aln",
 	"als",		"am",		"am1",		"ami",
 	"ami1",		"as",		"as1",		"asciify",
@@ -265,7 +265,7 @@ const char *__roff_name[MAN_MAX + 1] = {
 	"open",		"opena",	"os",		"output",
 	"padj",		"papersize",	"pc",		"pev",
 	"pi",		"PI",		"pl",		"pm",
-	"pn",		"pnr",		"po",		"ps",
+	"pn",		"pnr",		"ps",
 	"psbb",		"pshape",	"pso",		"ptr",
 	"pvs",		"rchar",	"rd",		"recursionlimit",
 	"return",	"rfschar",	"rhang",
@@ -335,6 +335,7 @@ static	struct roffmac	 roffs[TOKEN_NONE] = {
 	{ roff_onearg, NULL, NULL, 0 },  /* ft */
 	{ roff_onearg, NULL, NULL, 0 },  /* ll */
 	{ roff_onearg, NULL, NULL, 0 },  /* mc */
+	{ roff_onearg, NULL, NULL, 0 },  /* po */
 	{ roff_onearg, NULL, NULL, 0 },  /* rj */
 	{ roff_onearg, NULL, NULL, 0 },  /* sp */
 	{ roff_manyarg, NULL, NULL, 0 },  /* ta */
@@ -500,7 +501,6 @@ static	struct roffmac	 roffs[TOKEN_NONE] = {
 	{ roff_line_ignore, NULL, NULL, 0 },  /* pm */
 	{ roff_line_ignore, NULL, NULL, 0 },  /* pn */
 	{ roff_line_ignore, NULL, NULL, 0 },  /* pnr */
-	{ roff_line_ignore, NULL, NULL, 0 },  /* po */
 	{ roff_line_ignore, NULL, NULL, 0 },  /* ps */
 	{ roff_unsupp, NULL, NULL, 0 },  /* psbb */
 	{ roff_unsupp, NULL, NULL, 0 },  /* pshape */
diff --git a/roff.h b/roff.h
index 7cc4ad27..8cc3c2eb 100644
--- a/roff.h
+++ b/roff.h
@@ -1,4 +1,4 @@
-/*	$Id: roff.h,v 1.53 2017/06/14 13:00:31 schwarze Exp $	*/
+/*	$Id: roff.h,v 1.54 2017/06/14 22:51:25 schwarze Exp $	*/
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2013, 2014, 2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -77,6 +77,7 @@ enum	roff_tok {
 	ROFF_ft,
 	ROFF_ll,
 	ROFF_mc,
+	ROFF_po,
 	ROFF_rj,
 	ROFF_sp,
 	ROFF_ta,
@@ -245,7 +246,6 @@ enum	roff_tok {
 	ROFF_pm,
 	ROFF_pn,
 	ROFF_pnr,
-	ROFF_po,
 	ROFF_ps,
 	ROFF_psbb,
 	ROFF_pshape,
diff --git a/roff_html.c b/roff_html.c
index 7f440dfe..909604f8 100644
--- a/roff_html.c
+++ b/roff_html.c
@@ -1,4 +1,4 @@
-/*	$Id: roff_html.c,v 1.9 2017/06/14 13:00:31 schwarze Exp $ */
+/*	$Id: roff_html.c,v 1.10 2017/06/14 22:51:25 schwarze Exp $ */
 /*
  * Copyright (c) 2010 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2014, 2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -38,6 +38,7 @@ static	const roff_html_pre_fp roff_html_pre_acts[ROFF_MAX] = {
 	NULL,  /* ft */
 	NULL,  /* ll */
 	NULL,  /* mc */
+	NULL,  /* po */
 	roff_html_pre_ce,  /* rj */
 	roff_html_pre_sp,  /* sp */
 	NULL,  /* ta */
diff --git a/roff_term.c b/roff_term.c
index db59db08..0b0b6fda 100644
--- a/roff_term.c
+++ b/roff_term.c
@@ -1,4 +1,4 @@
-/*	$Id: roff_term.c,v 1.12 2017/06/14 17:51:15 schwarze Exp $ */
+/*	$Id: roff_term.c,v 1.13 2017/06/14 22:51:25 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2014, 2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
  *
@@ -32,6 +32,7 @@ static	void	  roff_term_pre_ce(ROFF_TERM_ARGS);
 static	void	  roff_term_pre_ft(ROFF_TERM_ARGS);
 static	void	  roff_term_pre_ll(ROFF_TERM_ARGS);
 static	void	  roff_term_pre_mc(ROFF_TERM_ARGS);
+static	void	  roff_term_pre_po(ROFF_TERM_ARGS);
 static	void	  roff_term_pre_sp(ROFF_TERM_ARGS);
 static	void	  roff_term_pre_ta(ROFF_TERM_ARGS);
 static	void	  roff_term_pre_ti(ROFF_TERM_ARGS);
@@ -42,6 +43,7 @@ static	const roff_term_pre_fp roff_term_pre_acts[ROFF_MAX] = {
 	roff_term_pre_ft,  /* ft */
 	roff_term_pre_ll,  /* ll */
 	roff_term_pre_mc,  /* mc */
+	roff_term_pre_po,  /* po */
 	roff_term_pre_ce,  /* rj */
 	roff_term_pre_sp,  /* sp */
 	roff_term_pre_ta,  /* ta */
@@ -153,6 +155,28 @@ roff_term_pre_mc(ROFF_TERM_ARGS)
 }
 
 static void
+roff_term_pre_po(ROFF_TERM_ARGS)
+{
+	struct roffsu	 su;
+	static int	 po, polast;
+	int		 ponew;
+
+	if (n->child != NULL &&
+	    a2roffsu(n->child->string, &su, SCALE_EM) != NULL) {
+		ponew = term_hen(p, &su);
+		if (*n->child->string == '+' ||
+		    *n->child->string == '-')
+			ponew += po;
+	} else
+		ponew = polast;
+	polast = po;
+	po = ponew;
+
+	ponew = po - polast + (int)p->tcol->offset;
+	p->tcol->offset = ponew > 0 ? ponew : 0;
+}
+
+static void
 roff_term_pre_sp(ROFF_TERM_ARGS)
 {
 	struct roffsu	 su;
diff --git a/roff_validate.c b/roff_validate.c
index b76f12ce..801e9314 100644
--- a/roff_validate.c
+++ b/roff_validate.c
@@ -1,4 +1,4 @@
-/*	$Id: roff_validate.c,v 1.8 2017/06/14 13:00:31 schwarze Exp $ */
+/*	$Id: roff_validate.c,v 1.9 2017/06/14 22:51:25 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2017 Ingo Schwarze <schwarze@openbsd.org>
  *
@@ -36,6 +36,7 @@ static	const roff_valid_fp roff_valids[ROFF_MAX] = {
 	roff_valid_ft,  /* ft */
 	NULL,  /* ll */
 	NULL,  /* mc */
+	NULL,  /* po */
 	NULL,  /* rj */
 	NULL,  /* sp */
 	NULL,  /* ta */