Polishing the worms in my favourite can, term_flushln().

The TERMP_TWOSPACE flag i introduced in August 2009 was idiosyncratic
and served only a very narrow purpose.  Replace it by a more intuitive
and more general termp attribute "trailspace", to be used together
with TERMP_NOBREAK, to request a minimum amount of whitespace at
the end of the current column.  Adapt all code to the new interface.

No functional change intended;
code reviews to confirm that are welcome *eg*.

4 files changed, 49 insertions, 29 deletions

diff --git a/man_term.c b/man_term.c
index 3c76f4cb..22668f02 100644
--- a/man_term.c
+++ b/man_term.c
@@ -265,7 +265,8 @@ pre_literal(DECL_ARGS)
 	if (MAN_HP == n->parent->tok && p->rmargin < p->maxrmargin) {
 		p->offset = p->rmargin;
 		p->rmargin = p->maxrmargin;
-		p->flags &= ~(TERMP_NOBREAK | TERMP_TWOSPACE);
+		p->trailspace = 0;
+		p->flags &= ~TERMP_NOBREAK;
 		p->flags |= TERMP_NOSPACE;
 	}
 
@@ -535,7 +536,7 @@ pre_HP(DECL_ARGS)
 
 	if ( ! (MANT_LITERAL & mt->fl)) {
 		p->flags |= TERMP_NOBREAK;
-		p->flags |= TERMP_TWOSPACE;
+		p->trailspace = 2;
 	}
 
 	len = mt->lmargin[mt->lmargincur];
@@ -570,7 +571,7 @@ post_HP(DECL_ARGS)
 	case (MAN_BODY):
 		term_newln(p);
 		p->flags &= ~TERMP_NOBREAK;
-		p->flags &= ~TERMP_TWOSPACE;
+		p->trailspace = 0;
 		p->offset = mt->offset;
 		p->rmargin = p->maxrmargin;
 		break;
@@ -613,6 +614,7 @@ pre_IP(DECL_ARGS)
 		break;
 	case (MAN_HEAD):
 		p->flags |= TERMP_NOBREAK;
+		p->trailspace = 1;
 		break;
 	case (MAN_BLOCK):
 		print_bvspace(p, n, mt->pardist);
@@ -675,6 +677,7 @@ post_IP(DECL_ARGS)
 	case (MAN_HEAD):
 		term_flushln(p);
 		p->flags &= ~TERMP_NOBREAK;
+		p->trailspace = 0;
 		p->rmargin = p->maxrmargin;
 		break;
 	case (MAN_BODY):
@@ -698,6 +701,7 @@ pre_TP(DECL_ARGS)
 	switch (n->type) {
 	case (MAN_HEAD):
 		p->flags |= TERMP_NOBREAK;
+		p->trailspace = 1;
 		break;
 	case (MAN_BODY):
 		p->flags |= TERMP_NOSPACE;
@@ -745,8 +749,8 @@ pre_TP(DECL_ARGS)
 	case (MAN_BODY):
 		p->offset = mt->offset + len;
 		p->rmargin = p->maxrmargin;
+		p->trailspace = 0;
 		p->flags &= ~TERMP_NOBREAK;
-		p->flags &= ~TERMP_TWOSPACE;
 		break;
 	default:
 		break;
@@ -1101,6 +1105,7 @@ print_man_foot(struct termp *p, const void *arg)
 	/* Bottom left corner: manual source. */
 
 	p->flags |= TERMP_NOSPACE | TERMP_NOBREAK;
+	p->trailspace = 1;
 	p->offset = 0;
 	p->rmargin = (p->maxrmargin - datelen + term_len(p, 1)) / 2;
 
@@ -1123,6 +1128,7 @@ print_man_foot(struct termp *p, const void *arg)
 
 	p->flags &= ~TERMP_NOBREAK;
 	p->flags |= TERMP_NOSPACE;
+	p->trailspace = 0;
 	p->offset = p->rmargin;
 	p->rmargin = p->maxrmargin;
 
@@ -1154,6 +1160,7 @@ print_man_head(struct termp *p, const void *arg)
 	titlen = term_strlen(p, title);
 
 	p->flags |= TERMP_NOBREAK | TERMP_NOSPACE;
+	p->trailspace = 1;
 	p->offset = 0;
 	p->rmargin = 2 * (titlen+1) + buflen < p->maxrmargin ?
 	    (p->maxrmargin - 
@@ -1176,6 +1183,7 @@ print_man_head(struct termp *p, const void *arg)
 	/* Top right corner: title and section, again. */
 
 	p->flags &= ~TERMP_NOBREAK;
+	p->trailspace = 0;
 	if (p->rmargin + titlen <= p->maxrmargin) {
 		p->flags |= TERMP_NOSPACE;
 		p->offset = p->rmargin;
diff --git a/mdoc_term.c b/mdoc_term.c
index a9b41f15..e10ded9b 100644
--- a/mdoc_term.c
+++ b/mdoc_term.c
@@ -1,7 +1,7 @@
 /*	$Id$ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2010, 2012 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2010, 2012, 2013 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
@@ -424,6 +424,7 @@ print_mdoc_foot(struct termp *p, const void *arg)
 	p->offset = 0;
 	p->rmargin = (p->maxrmargin - 
 			term_strlen(p, meta->date) + term_len(p, 1)) / 2;
+	p->trailspace = 1;
 	p->flags |= TERMP_NOSPACE | TERMP_NOBREAK;
 
 	term_word(p, meta->os);
@@ -438,6 +439,7 @@ print_mdoc_foot(struct termp *p, const void *arg)
 
 	p->offset = p->rmargin;
 	p->rmargin = p->maxrmargin;
+	p->trailspace = 0;
 	p->flags &= ~TERMP_NOBREAK;
 	p->flags |= TERMP_NOSPACE;
 
@@ -489,6 +491,7 @@ print_mdoc_head(struct termp *p, const void *arg)
 	titlen = term_strlen(p, title);
 
 	p->flags |= TERMP_NOBREAK | TERMP_NOSPACE;
+	p->trailspace = 1;
 	p->offset = 0;
 	p->rmargin = 2 * (titlen+1) + buflen < p->maxrmargin ?
 	    (p->maxrmargin -
@@ -507,6 +510,7 @@ print_mdoc_head(struct termp *p, const void *arg)
 	term_flushln(p);
 
 	p->flags &= ~TERMP_NOBREAK;
+	p->trailspace = 0;
 	if (p->rmargin + titlen <= p->maxrmargin) {
 		p->flags |= TERMP_NOSPACE;
 		p->offset = p->rmargin;
@@ -794,13 +798,13 @@ termp_it_pre(DECL_ARGS)
 	case (LIST_dash):
 		/* FALLTHROUGH */
 	case (LIST_hyphen):
-		if (MDOC_HEAD == n->type)
-			p->flags |= TERMP_NOBREAK;
+		if (MDOC_HEAD != n->type)
+			break;
+		p->flags |= TERMP_NOBREAK;
+		p->trailspace = 1;
 		break;
 	case (LIST_hang):
-		if (MDOC_HEAD == n->type)
-			p->flags |= TERMP_NOBREAK;
-		else
+		if (MDOC_HEAD != n->type)
 			break;
 
 		/*
@@ -812,16 +816,18 @@ termp_it_pre(DECL_ARGS)
 		if (n->next->child && 
 				(MDOC_Bl == n->next->child->tok ||
 				 MDOC_Bd == n->next->child->tok))
-			p->flags &= ~TERMP_NOBREAK;
-		else
-			p->flags |= TERMP_HANG;
+			break;
+
+		p->flags |= TERMP_NOBREAK | TERMP_HANG;
+		p->trailspace = 1;
 		break;
 	case (LIST_tag):
-		if (MDOC_HEAD == n->type)
-			p->flags |= TERMP_NOBREAK | TERMP_TWOSPACE;
-
 		if (MDOC_HEAD != n->type)
 			break;
+
+		p->flags |= TERMP_NOBREAK;
+		p->trailspace = 2;
+
 		if (NULL == n->next || NULL == n->next->child)
 			p->flags |= TERMP_DANGLE;
 		break;
@@ -829,15 +835,20 @@ termp_it_pre(DECL_ARGS)
 		if (MDOC_HEAD == n->type)
 			break;
 
-		if (NULL == n->next)
+		if (NULL == n->next) {
 			p->flags &= ~TERMP_NOBREAK;
-		else
+			p->trailspace = 0;
+		} else {
 			p->flags |= TERMP_NOBREAK;
+			p->trailspace = 1;
+		}
 
 		break;
 	case (LIST_diag):
-		if (MDOC_HEAD == n->type)
-			p->flags |= TERMP_NOBREAK;
+		if (MDOC_HEAD != n->type)
+			break;
+		p->flags |= TERMP_NOBREAK;
+		p->trailspace = 1;
 		break;
 	default:
 		break;
@@ -989,8 +1000,8 @@ termp_it_post(DECL_ARGS)
 
 	p->flags &= ~TERMP_DANGLE;
 	p->flags &= ~TERMP_NOBREAK;
-	p->flags &= ~TERMP_TWOSPACE;
 	p->flags &= ~TERMP_HANG;
+	p->trailspace = 0;
 }
 
 
@@ -1023,6 +1034,7 @@ termp_nm_pre(DECL_ARGS)
 
 	if (MDOC_HEAD == n->type && n->next->child) {
 		p->flags |= TERMP_NOSPACE | TERMP_NOBREAK;
+		p->trailspace = 1;
 		p->rmargin = p->offset + term_len(p, 1);
 		if (NULL == n->child) {
 			p->rmargin += term_strlen(p, meta->name);
@@ -1051,6 +1063,7 @@ termp_nm_post(DECL_ARGS)
 	if (MDOC_HEAD == n->type && n->next->child) {
 		term_flushln(p);
 		p->flags &= ~(TERMP_NOBREAK | TERMP_HANG);
+		p->trailspace = 0;
 	} else if (MDOC_BODY == n->type && n->child)
 		term_flushln(p);
 }
diff --git a/term.c b/term.c
index c19b097d..f5f1882d 100644
--- a/term.c
+++ b/term.c
@@ -83,9 +83,8 @@ term_end(struct termp *p)
  *  - TERMP_NOBREAK: this is the most important and is used when making
  *    columns.  In short: don't print a newline and instead expect the
  *    next call to do the padding up to the start of the next column.
- *
- *  - TERMP_TWOSPACE: make sure there is room for at least two space
- *    characters of padding.  Otherwise, rather break the line.
+ *    p->trailspace may be set to 0, 1, or 2, depending on how many
+ *    space characters are required at the end of the column.
  *
  *  - TERMP_DANGLE: don't newline when TERMP_NOBREAK is specified and
  *    the line is overrun, and don't pad-right if it's underrun.
@@ -269,8 +268,8 @@ term_flushln(struct termp *p)
 	}
 
 	if (TERMP_HANG & p->flags) {
-		/* We need one blank after the tag. */
-		p->overstep = (int)(vis - maxvis + (*p->width)(p, ' '));
+		p->overstep = (int)(vis - maxvis +
+				p->trailspace * (*p->width)(p, ' '));
 
 		/*
 		 * If we have overstepped the margin, temporarily move
@@ -285,8 +284,7 @@ term_flushln(struct termp *p)
 		return;
 
 	/* If the column was overrun, break the line. */
-	if (maxvis <= vis +
-	    ((TERMP_TWOSPACE & p->flags) ? (*p->width)(p, ' ') : 0)) {
+	if (maxvis < vis + p->trailspace * (*p->width)(p, ' ')) {
 		(*p->endline)(p);
 		p->viscol = 0;
 	}
diff --git a/term.h b/term.h
index 2c6ece97..880fefb1 100644
--- a/term.h
+++ b/term.h
@@ -1,6 +1,7 @@
 /*	$Id$ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
+ * Copyright (c) 2011, 2012, 2013 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
@@ -63,6 +64,7 @@ struct	termp {
 	size_t		  tabwidth;	/* Distance of tab positions. */
 	size_t		  col;		/* Bytes in buf. */
 	size_t		  viscol;	/* Chars on current line. */
+	size_t		  trailspace;	/* See termp_flushln(). */
 	int		  overstep;	/* See termp_flushln(). */
 	int		  skipvsp;	/* Vertical space to skip. */
 	int		  flags;
@@ -73,7 +75,6 @@ struct	termp {
 #define	TERMP_NONOSPACE	 (1 << 7)	/* No space (no autounset). */
 #define	TERMP_DANGLE	 (1 << 8)	/* See term_flushln(). */
 #define	TERMP_HANG	 (1 << 9)	/* See term_flushln(). */
-#define	TERMP_TWOSPACE	 (1 << 10)	/* See term_flushln(). */
 #define	TERMP_NOSPLIT	 (1 << 11)	/* See termp_an_pre/post(). */
 #define	TERMP_SPLIT	 (1 << 12)	/* See termp_an_pre/post(). */
 #define	TERMP_ANPREC	 (1 << 13)	/* See termp_an_pre(). */