Introduce the concept of nodes that are semantically transparent:

they are skipped when looking for previous or following high-level
macros.  Examples include roff(7) .ft, .ll, and .ta, mdoc(7) .Sm
and .Tg, and man(7) .DT and .PD.  Use this concept for a variety
of improved decisions in various validators and formatters.

While here,
* remove a few const qualifiers on struct arguments that caused trouble;
* get rid of some more Yoda notation in the vicinity;
* and apply some other stylistic improvements in the vicinity.

I found this class of issues while considering .Tg patches from kn@.

1 files changed, 49 insertions, 38 deletions

diff --git a/mdoc_man.c b/mdoc_man.c
index d404fc7d..d7b42fac 100644
--- a/mdoc_man.c
+++ b/mdoc_man.c
@@ -1,4 +1,4 @@
-/*	$Id: mdoc_man.c,v 1.135 2020/02/20 22:55:42 schwarze Exp $ */
+/*	$Id: mdoc_man.c,v 1.136 2020/02/27 01:43:52 schwarze Exp $ */
 /*
  * Copyright (c) 2011-2020 Ingo Schwarze <schwarze@openbsd.org>
  *
@@ -113,7 +113,7 @@ static	int	  pre_sm(DECL_ARGS);
 static	void	  pre_sp(DECL_ARGS);
 static	int	  pre_sect(DECL_ARGS);
 static	int	  pre_sy(DECL_ARGS);
-static	void	  pre_syn(const struct roff_node *);
+static	void	  pre_syn(struct roff_node *);
 static	void	  pre_ta(DECL_ARGS);
 static	int	  pre_vt(DECL_ARGS);
 static	int	  pre_xr(DECL_ARGS);
@@ -650,7 +650,9 @@ print_node(DECL_ARGS)
 	 * Break the line if we were parsed subsequent the current node.
 	 * This makes the page structure be more consistent.
 	 */
-	if (MMAN_spc & outflags && NODE_LINE & n->flags)
+	if (outflags & MMAN_spc &&
+	    n->flags & NODE_LINE &&
+	    !roff_node_transparent(n))
 		outflags |= MMAN_nl;
 
 	act = NULL;
@@ -777,13 +779,20 @@ post_font(DECL_ARGS)
 static void
 post_percent(DECL_ARGS)
 {
+	struct roff_node *np, *nn, *nnn;
 
 	if (mdoc_man_act(n->tok)->pre == pre_em)
 		font_pop();
-	if (n->next) {
-		print_word(",");
-		if (n->prev &&	n->prev->tok == n->tok &&
-				n->next->tok == n->tok)
+
+	if ((nn = roff_node_next(n)) != NULL) {
+		np = roff_node_prev(n);
+		nnn = nn == NULL ? NULL : roff_node_next(nn);
+		if (nn->tok != n->tok ||
+		    (np != NULL && np->tok == n->tok) ||
+		    (nnn != NULL && nnn->tok == n->tok))
+			print_word(",");
+		if (nn->tok == n->tok &&
+		    (nnn == NULL || nnn->tok != n->tok))
 			print_word("and");
 	} else {
 		print_word(".");
@@ -851,13 +860,15 @@ post_sect(DECL_ARGS)
 
 /* See mdoc_term.c, synopsis_pre() for comments. */
 static void
-pre_syn(const struct roff_node *n)
+pre_syn(struct roff_node *n)
 {
+	struct roff_node *np;
 
-	if (NULL == n->prev || ! (NODE_SYNPRETTY & n->flags))
+	if ((n->flags & NODE_SYNPRETTY) == 0 ||
+	    (np = roff_node_prev(n)) == NULL)
 		return;
 
-	if (n->prev->tok == n->tok &&
+	if (np->tok == n->tok &&
 	    MDOC_Ft != n->tok &&
 	    MDOC_Fo != n->tok &&
 	    MDOC_Fn != n->tok) {
@@ -865,7 +876,7 @@ pre_syn(const struct roff_node *n)
 		return;
 	}
 
-	switch (n->prev->tok) {
+	switch (np->tok) {
 	case MDOC_Fd:
 	case MDOC_Fn:
 	case MDOC_Fo:
@@ -941,11 +952,10 @@ static int
 pre_bd(DECL_ARGS)
 {
 	outflags &= ~(MMAN_PP | MMAN_sp | MMAN_br);
-
-	if (DISP_unfilled == n->norm->Bd.type ||
-	    DISP_literal  == n->norm->Bd.type)
+	if (n->norm->Bd.type == DISP_unfilled ||
+	    n->norm->Bd.type == DISP_literal)
 		print_line(".nf", 0);
-	if (0 == n->norm->Bd.comp && NULL != n->parent->prev)
+	if (n->norm->Bd.comp == 0 && roff_node_prev(n->parent) != NULL)
 		outflags |= MMAN_sp;
 	print_offs(n->norm->Bd.offs, 1);
 	return 1;
@@ -977,7 +987,7 @@ post_bd(DECL_ARGS)
 	}
 
 	/* Maybe we are inside an enclosing list? */
-	if (NULL != n->parent->next)
+	if (roff_node_next(n->parent) != NULL)
 		mid_it();
 }
 
@@ -1102,16 +1112,15 @@ post_bl(DECL_ARGS)
 		print_line(".RE", MMAN_nl);
 		assert(Bl_stack_len);
 		Bl_stack_len--;
-		assert(0 == Bl_stack[Bl_stack_len]);
+		assert(Bl_stack[Bl_stack_len] == 0);
 	} else {
 		outflags |= MMAN_PP | MMAN_nl;
 		outflags &= ~(MMAN_sp | MMAN_br);
 	}
 
 	/* Maybe we are inside an enclosing list? */
-	if (NULL != n->parent->next)
+	if (roff_node_next(n->parent) != NULL)
 		mid_it();
-
 }
 
 static void
@@ -1123,7 +1132,6 @@ pre_br(DECL_ARGS)
 static int
 pre_dl(DECL_ARGS)
 {
-
 	print_offs("6n", 0);
 	return 1;
 }
@@ -1131,11 +1139,10 @@ pre_dl(DECL_ARGS)
 static void
 post_dl(DECL_ARGS)
 {
-
 	print_line(".RE", MMAN_nl);
 
 	/* Maybe we are inside an enclosing list? */
-	if (NULL != n->parent->next)
+	if (roff_node_next(n->parent) != NULL)
 		mid_it();
 }
 
@@ -1236,15 +1243,15 @@ pre_fa(DECL_ARGS)
 static void
 post_fa(DECL_ARGS)
 {
+	struct roff_node *nn;
 
-	if (NULL != n->next && MDOC_Fa == n->next->tok)
+	if ((nn = roff_node_next(n)) != NULL && nn->tok == MDOC_Fa)
 		print_word(",");
 }
 
 static int
 pre_fd(DECL_ARGS)
 {
-
 	pre_syn(n);
 	font_push('B');
 	return 1;
@@ -1253,7 +1260,6 @@ pre_fd(DECL_ARGS)
 static void
 post_fd(DECL_ARGS)
 {
-
 	font_pop();
 	outflags |= MMAN_br;
 }
@@ -1261,7 +1267,6 @@ post_fd(DECL_ARGS)
 static int
 pre_fl(DECL_ARGS)
 {
-
 	font_push('B');
 	print_word("\\-");
 	if (n->child != NULL)
@@ -1272,12 +1277,13 @@ pre_fl(DECL_ARGS)
 static void
 post_fl(DECL_ARGS)
 {
+	struct roff_node *nn;
 
 	font_pop();
-	if (!(n->child != NULL ||
-	    n->next == NULL ||
-	    n->next->type == ROFFT_TEXT ||
-	    n->next->flags & NODE_LINE))
+	if (n->child == NULL &&
+	    ((nn = roff_node_next(n)) != NULL &&
+	    nn->type != ROFFT_TEXT &&
+	    (nn->flags & NODE_LINE) == 0))
 		outflags &= ~MMAN_spc;
 }
 
@@ -1420,9 +1426,9 @@ pre_it(DECL_ARGS)
 	case ROFFT_HEAD:
 		outflags |= MMAN_PP | MMAN_nl;
 		bln = n->parent->parent;
-		if (0 == bln->norm->Bl.comp ||
-		    (NULL == n->parent->prev &&
-		     NULL == bln->parent->prev))
+		if (bln->norm->Bl.comp == 0 ||
+		    (n->parent->prev == NULL &&
+		     roff_node_prev(bln->parent) == NULL))
 			outflags |= MMAN_sp;
 		outflags &= ~MMAN_br;
 		switch (bln->norm->Bl.type) {
@@ -1634,17 +1640,22 @@ pre_nm(DECL_ARGS)
 {
 	char	*name;
 
-	if (n->type == ROFFT_BLOCK) {
+	switch (n->type) {
+	case ROFFT_BLOCK:
 		outflags |= MMAN_Bk;
 		pre_syn(n);
-	}
-	if (n->type != ROFFT_ELEM && n->type != ROFFT_HEAD)
 		return 1;
+	case ROFFT_HEAD:
+	case ROFFT_ELEM:
+		break;
+	default:
+		return 1;
+	}
 	name = n->child == NULL ? NULL : n->child->string;
-	if (NULL == name)
+	if (name == NULL)
 		return 0;
 	if (n->type == ROFFT_HEAD) {
-		if (NULL == n->parent->prev)
+		if (roff_node_prev(n->parent) == NULL)
 			outflags |= MMAN_sp;
 		print_block(".HP", 0);
 		printf(" %dn", man_strlen(name) + 1);