Allow registers to be unset. Implement and document the `.nr nS val'.

5 files changed, 41 insertions, 13 deletions

diff --git a/mdoc.c b/mdoc.c
index f2f5f1cf..59c54b83 100644
--- a/mdoc.c
+++ b/mdoc.c
@@ -380,6 +380,15 @@ node_alloc(struct mdoc *m, int line, int pos,
 	if (SEC_SYNOPSIS == p->sec)
 		p->flags |= MDOC_SYNPRETTY;
 
+	/* Register analysis. */
+
+	if (m->regs->regs[(int)REG_nS].set) {
+		if (m->regs->regs[(int)REG_nS].v.u)
+			p->flags |= MDOC_SYNPRETTY;
+		else
+			p->flags &= ~MDOC_SYNPRETTY;
+	}
+
 	return(p);
 }
 
diff --git a/mdoc_validate.c b/mdoc_validate.c
index 8615ad46..99c2e359 100644
--- a/mdoc_validate.c
+++ b/mdoc_validate.c
@@ -806,6 +806,8 @@ pre_sh(PRE_ARGS)
 
 	if (MDOC_BLOCK != n->type)
 		return(1);
+
+	mdoc->regs->regs[(int)REG_nS].set = 0;
 	return(check_parent(mdoc, n, MDOC_MAX, MDOC_ROOT));
 }
 
diff --git a/regs.h b/regs.h
index ca388597..0bec3a53 100644
--- a/regs.h
+++ b/regs.h
@@ -24,10 +24,21 @@ enum	regs {
 	REG__MAX
 };
 
-struct	regset {
+struct	reg {
+	int		 set; /* whether set or not */
 	union {
-		int	 i; /* integer value */
-	} regs[REG__MAX];
+		unsigned u; /* unsigned integer */
+	} v;
+};
+
+/*
+ * Registers are non-scoped state.  These can be manipulated directly in
+ * libroff or indirectly in libman or libmdoc by macros.  These should
+ * be implemented sparingly (we are NOT roffdoc!) and documented fully
+ * in roff.7.
+ */
+struct	regset {
+	struct reg	 regs[REG__MAX];
 };
 
 __END_DECLS
diff --git a/roff.7 b/roff.7
index e35f37d4..44759861 100644
--- a/roff.7
+++ b/roff.7
@@ -289,12 +289,15 @@ requests are recognised:
 .It Cm nS
 If set to a positive integer value, certain
 .Xr mdoc 7
-macros will behave as if they are defined in the
+macros will behave as if they were defined in the
 .Em SYNOPSIS
-section to a manual.
+section.
 Otherwise, this behaviour is unset (even if called within the
 .Em SYNOPSIS
 section itself).
+Note that invoking a new
+.Xr mdoc 7
+section will unset this value.
 .El
 .Ss \&tr
 Output character translation.
diff --git a/roff.c b/roff.c
index 15d4cfe6..9d2294c6 100644
--- a/roff.c
+++ b/roff.c
@@ -155,7 +155,7 @@ static	int		 roffnode_push(struct roff *,
 				enum rofft, int, int);
 static	void		 roffnode_pop(struct roff *);
 static	enum rofft	 roff_parse(const char *, int *);
-static	int		 roff_parse_nat(const char *, int *);
+static	int		 roff_parse_nat(const char *, unsigned int *);
 
 /* See roff_hash_find() */
 #define	ROFF_HASH(p)	(p[0] - ASCII_LO)
@@ -425,7 +425,7 @@ roff_parse(const char *buf, int *pos)
 
 
 static int
-roff_parse_nat(const char *buf, int *res)
+roff_parse_nat(const char *buf, unsigned int *res)
 {
 	char		*ep;
 	long		 lval;
@@ -436,10 +436,10 @@ roff_parse_nat(const char *buf, int *res)
 		return(0);
 	if ((errno == ERANGE && 
 			(lval == LONG_MAX || lval == LONG_MIN)) ||
-			(lval > INT_MAX || lval <= 0))
+			(lval > INT_MAX || lval < 0))
 		return(0);
 
-	*res = (int)lval;
+	*res = (unsigned int)lval;
 	return(1);
 }
 
@@ -882,8 +882,10 @@ static enum rofferr
 roff_nr(ROFF_ARGS)
 {
 	const char	*key, *val;
+	struct reg	*rg;
 
 	key = &(*bufp)[pos];
+	rg = r->regs->regs;
 
 	/* Parse register request. */
 	while ((*bufp)[pos] && ' ' != (*bufp)[pos])
@@ -905,11 +907,12 @@ roff_nr(ROFF_ARGS)
 	/* Process register token. */
 
 	if (0 == strcmp(key, "nS")) {
-		if ( ! roff_parse_nat(val, &r->regs->regs[(int)REG_nS].i))
-			r->regs->regs[(int)REG_nS].i = 0;
+		rg[(int)REG_nS].set = 1;
+		if ( ! roff_parse_nat(val, &rg[(int)REG_nS].v.u))
+			rg[(int)REG_nS].v.u = 0;
 
-		ROFF_DEBUG("roff: register nS: %d\n", 
-				r->regs->regs[(int)REG_nS].i);
+		ROFF_DEBUG("roff: register nS: %u\n", 
+				rg[(int)REG_nS].v.u);
 	} else
 		ROFF_DEBUG("roff: ignoring register: %s\n", key);