Implement the roff(7) .nop (no operation) request.

Examples of manual pages (ab)using it
include groff(7), chem(1), groff_mom(7), and groff_hdtbl(7).

diff --git a/share/man/man7/roff.7 b/share/man/man7/roff.7
index daddc9c..5721081 100644 (file)
--- a/share/man/man7/roff.7
+++ b/share/man/man7/roff.7
@@ -1,4 +1,4 @@
-.\"    $OpenBSD: roff.7,v 1.76 2018/04/10 00:52:21 schwarze Exp $
+.\"    $OpenBSD: roff.7,v 1.77 2018/08/10 04:41:21 schwarze Exp $
 .\"
 .\" Copyright (c) 2010, 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2010-2018 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: April 10 2018 $
+.Dd $Mdocdate: August 10 2018 $
 .Dt ROFF 7
 .Os
 .Sh NAME
@@ -204,7 +204,7 @@ Unescaped trailing spaces are stripped from text line input unless in a
 literal context.
 In general, trailing whitespace on any input line is discouraged for
 reasons of portability.
-In the rare case that a blank character is needed at the end of an
+In the rare case that a space character is needed at the end of an
 input line, it may be forced by
 .Sq \e\ \e& .
 .Pp
@@ -663,7 +663,7 @@ produces
 .Pp
 in the input stream, and thus in the output: \fI\^XtFree\^\fP.
 Each occurrence of \e\e$* is replaced with all the arguments,
-joined together with single blank characters.
+joined together with single space characters.
 .Pp
 Since macros and user-defined strings share a common string table,
 defining a macro
@@ -1344,8 +1344,11 @@ Currently unsupported.
 Temporarily turn off line numbering.
 Currently unsupported.
 .It Ic \&nop Ar body
-Execute the rest of the input line as a request or macro line.
-Currently unsupported.
+Execute the rest of the input line as a request, macro, or text line,
+skipping the
+.Ic \&nop
+request and any space characters immediately following it.
+This is mostly used to indent text lines inside macro definitions.
 .It Ic \&nr Ar register Oo Cm + Ns | Ns Cm - Oc Ns Ar expression Op Ar stepsize
 Define or change a register.
 A register is an arbitrary string value that defines some sort of state,

diff --git a/usr.bin/mandoc/roff.c b/usr.bin/mandoc/roff.c
index 2e4e9c1..71b595a 100644 (file)
--- a/usr.bin/mandoc/roff.c
+++ b/usr.bin/mandoc/roff.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: roff.c,v 1.201 2018/08/01 15:39:47 schwarze Exp $ */
+/*     $OpenBSD: roff.c,v 1.202 2018/08/10 04:41:21 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015, 2017, 2018 Ingo Schwarze <schwarze@openbsd.org>
@@ -195,6 +195,7 @@ static      enum rofferr     roff_line_ignore(ROFF_ARGS);
 static void             roff_man_alloc1(struct roff_man *);
 static void             roff_man_free1(struct roff_man *);
 static enum rofferr     roff_manyarg(ROFF_ARGS);
+static enum rofferr     roff_nop(ROFF_ARGS);
 static enum rofferr     roff_nr(ROFF_ARGS);
 static enum rofferr     roff_onearg(ROFF_ARGS);
 static enum roff_tok    roff_parse(struct roff *, char *, int *,
@@ -488,7 +489,7 @@ static      struct roffmac   roffs[TOKEN_NONE] = {
        { roff_line_ignore, NULL, NULL, 0 },  /* nhychar */
        { roff_unsupp, NULL, NULL, 0 },  /* nm */
        { roff_unsupp, NULL, NULL, 0 },  /* nn */
-       { roff_unsupp, NULL, NULL, 0 },  /* nop */
+       { roff_nop, NULL, NULL, 0 },  /* nop */
        { roff_nr, NULL, NULL, 0 },  /* nr */
        { roff_unsupp, NULL, NULL, 0 },  /* nrf */
        { roff_line_ignore, NULL, NULL, 0 },  /* nroff */
@@ -3158,6 +3159,15 @@ roff_eo(ROFF_ARGS)
        return ROFF_IGN;
 }
 
+static enum rofferr
+roff_nop(ROFF_ARGS)
+{
+       while (buf->buf[pos] == ' ')
+               pos++;
+       *offs = pos;
+       return ROFF_RERUN;
+}
+
 static enum rofferr
 roff_tr(ROFF_ARGS)
 {