Support for badly nested blocks, written around the time of

the Rostock mandoc hackathon and tested and polished since,
supporting constructs like:

.Ao Bo    Ac    Bc        (exp breaking exp)
.Aq Bo    eol   Bc        (imp breaking exp)
.Ao Bq    Ac    eol       (exp breaking imp)
.Ao Bo So Bc    Ac  Sc    (double break, inner before outer)
.Ao Bo So Ac    Bc  Sc    (double break, outer before inner)
.Ao Bo    Ac So Bc  Sc    (broken breaker)
.Ao Bo So Bc Do Ac  Sc Dc (broken double breaker)

There are still two known issues which are tricky:

1) Breaking two identical explicit blocks (Ao Bo Bo Ac or Aq Bo Bo eol)
fails outright, triggering a bogus syntax error.
2) Breaking a block by two identical explicit blocks (Ao Ao Bo Ac Ac Bc
or Ao Ao Bq Ac Ac eol) still has a minor rendering error left:
"<ao1 <ao2 [bo ac2> ac1> bc]>" should not have the final ">".

We can fix these later in the tree, let's not grow this diff too large.

"get it in" kristaps@

8 files changed, 329 insertions, 95 deletions

diff --git a/libmdoc.h b/libmdoc.h
index d0a8a979..f4aba6a5 100644
--- a/libmdoc.h
+++ b/libmdoc.h
@@ -1,4 +1,4 @@
-/*	$Id: libmdoc.h,v 1.57 2010/06/27 16:18:13 kristaps Exp $ */
+/*	$Id: libmdoc.h,v 1.58 2010/06/29 19:20:38 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -109,6 +109,9 @@ int		  mdoc_block_alloc(struct mdoc *, int, int,
 int		  mdoc_head_alloc(struct mdoc *, int, int, enum mdoct);
 int		  mdoc_tail_alloc(struct mdoc *, int, int, enum mdoct);
 int		  mdoc_body_alloc(struct mdoc *, int, int, enum mdoct);
+int		  mdoc_endbody_alloc(struct mdoc *m, int line, int pos,
+			enum mdoct tok, struct mdoc_node *body,
+			enum mdoc_endbody end);
 void		  mdoc_node_delete(struct mdoc *, struct mdoc_node *);
 void		  mdoc_hash_init(void);
 enum mdoct	  mdoc_hash_find(const char *);
diff --git a/mdoc.3 b/mdoc.3
index 8b15b998..f65b4c39 100644
--- a/mdoc.3
+++ b/mdoc.3
@@ -1,4 +1,4 @@
-.\"	$Id: mdoc.3,v 1.44 2010/06/27 16:18:13 kristaps Exp $
+.\"	$Id: mdoc.3,v 1.45 2010/06/29 19:20:38 schwarze Exp $
 .\"
 .\" Copyright (c) 2009-2010 Kristaps Dzonsons <kristaps@bsd.lv>
 .\"
@@ -14,7 +14,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: June 27 2010 $
+.Dd $Mdocdate: June 29 2010 $
 .Dt MDOC 3
 .Os
 .Sh NAME
@@ -217,10 +217,14 @@ and
 fields), its position in the tree (the
 .Va parent ,
 .Va child ,
+.Va nchild ,
 .Va next
 and
 .Va prev
-fields) and some type-specific data.
+fields) and some type-specific data, in particular, for nodes generated
+from macros, the generating macro in the
+.Va tok
+field.
 .Pp
 The tree itself is arranged according to the following normal form,
 where capitalised non-terminals represent nodes.
@@ -235,11 +239,11 @@ where capitalised non-terminals represent nodes.
 .It ELEMENT
 \(<- TEXT*
 .It HEAD
-\(<- mnode+
+\(<- mnode*
 .It BODY
-\(<- mnode+
+\(<- mnode* [ENDBODY mnode*]
 .It TAIL
-\(<- mnode+
+\(<- mnode*
 .It TEXT
 \(<- [[:printable:],0x1e]*
 .El
@@ -253,6 +257,65 @@ an empty line will produce a zero-length string.
 Multiple body parts are only found in invocations of
 .Sq \&Bl \-column ,
 where a new body introduces a new phrase.
+.Ss Badly nested blocks
+A special kind of node is available to end the formatting
+associated with a given block before the physical end of that block.
+Such an ENDBODY node has a non-null
+.Va end
+field, is of the BODY
+.Va type ,
+has the same
+.Va tok
+as the BLOCK it is ending, and has a
+.Va pending
+field pointing to that BLOCK's BODY node.
+It is an indirect child of that BODY node
+and has no children of its own.
+.Pp
+An ENDBODY node is generated when a block ends while one of its child
+blocks is still open, like in the following example:
+.Bd -literal -offset indent
+\&.Ao ao
+\&.Bo bo ac
+\&.Ac bc
+\&.Bc end
+.Ed
+.Pp
+This example results in the following block structure:
+.Bd -literal -offset indent
+BLOCK Ao
+	HEAD Ao
+	BODY Ao
+		TEXT ao
+		BLOCK Bo, pending -> Ao
+			HEAD Bo
+			BODY Bo
+				TEXT bo
+				TEXT ac
+				ENDBODY Ao, pending -> Ao
+				TEXT bc
+TEXT end
+.Ed
+.Pp
+Here, the formatting of the Ao block extends from TEXT ao to TEXT ac,
+while the formatting of the Bo block extends from TEXT bo to TEXT bc,
+rendering like this in
+.Fl T Ns Cm ascii
+mode:
+.Dl <ao [bo ac> bc] end
+Support for badly nested blocks is only provided for backward
+compatibility with some older
+.Xr mdoc 7
+implementations.
+Using them in new code is stronly discouraged:
+Some frontends, in particular
+.Fl T Ns Cm html ,
+are unable to render them in any meaningful way,
+many other
+.Xr mdoc 7
+implementations do not support them, and even for those that do,
+the behaviour is not well-defined, in particular when using multiple
+levels of badly nested blocks.
 .Sh EXAMPLES
 The following example reads lines from stdin and parses them, operating
 on the finished parse tree with
diff --git a/mdoc.c b/mdoc.c
index 1184c641..4544e785 100644
--- a/mdoc.c
+++ b/mdoc.c
@@ -1,4 +1,4 @@
-/*	$Id: mdoc.c,v 1.151 2010/06/27 16:36:22 kristaps Exp $ */
+/*	$Id: mdoc.c,v 1.152 2010/06/29 19:20:38 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -332,6 +332,8 @@ node_append(struct mdoc *mdoc, struct mdoc_node *p)
 		p->parent->tail = p;
 		break;
 	case (MDOC_BODY):
+		if (p->end)
+			break;
 		assert(MDOC_BLOCK == p->parent->type);
 		p->parent->body = p;
 		break;
@@ -436,6 +438,22 @@ mdoc_body_alloc(struct mdoc *m, int line, int pos, enum mdoct tok)
 
 
 int
+mdoc_endbody_alloc(struct mdoc *m, int line, int pos, enum mdoct tok,
+		struct mdoc_node *body, enum mdoc_endbody end)
+{
+	struct mdoc_node *p;
+
+	p = node_alloc(m, line, pos, tok, MDOC_BODY);
+	p->pending = body;
+	p->end = end;
+	if ( ! node_append(m, p))
+		return(0);
+	m->next = MDOC_NEXT_SIBLING;
+	return(1);
+}
+
+
+int
 mdoc_block_alloc(struct mdoc *m, int line, int pos, 
 		enum mdoct tok, struct mdoc_arg *args)
 {
diff --git a/mdoc.h b/mdoc.h
index 485cfc61..06f97688 100644
--- a/mdoc.h
+++ b/mdoc.h
@@ -1,4 +1,4 @@
-/*	$Id: mdoc.h,v 1.94 2010/06/27 16:18:13 kristaps Exp $ */
+/*	$Id: mdoc.h,v 1.95 2010/06/29 19:20:38 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -249,6 +249,12 @@ struct 	mdoc_arg {
 	unsigned int	  refcnt;
 };
 
+enum	mdoc_endbody {
+	ENDBODY_NOT = 0,
+	ENDBODY_SPACE,
+	ENDBODY_NOSPACE,
+};
+
 enum	mdoc_list {
 	LIST__NONE = 0,
 	LIST_bullet,
@@ -302,6 +308,7 @@ struct	mdoc_node {
 #define	MDOC_EOS	 (1 << 2) /* at sentence boundary */
 #define	MDOC_LINE	 (1 << 3) /* first macro/text on line */
 #define	MDOC_SYNPRETTY	 (1 << 4) /* SYNOPSIS-style formatting */
+#define	MDOC_ENDED	 (1 << 5) /* rendering has been ended */
 	enum mdoc_type	  type; /* AST node type */
 	enum mdoc_sec	  sec; /* current named section */
 	/* FIXME: these can be union'd to shave a few bytes. */
@@ -311,6 +318,7 @@ struct	mdoc_node {
 	struct mdoc_node *body;		/* BLOCK */
 	struct mdoc_node *tail;		/* BLOCK */
 	char		 *string;	/* TEXT */
+	enum mdoc_endbody end;		/* BODY */
 
 	union {
 		struct mdoc_bl Bl;
diff --git a/mdoc_html.c b/mdoc_html.c
index 38538cdb..398152d6 100644
--- a/mdoc_html.c
+++ b/mdoc_html.c
@@ -1,4 +1,4 @@
-/*	$Id: mdoc_html.c,v 1.87 2010/06/27 16:18:13 kristaps Exp $ */
+/*	$Id: mdoc_html.c,v 1.88 2010/06/29 19:20:38 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -437,7 +437,7 @@ print_mdoc_node(MDOC_ARGS)
 		print_text(h, n->string);
 		return;
 	default:
-		if (mdocs[n->tok].pre)
+		if (mdocs[n->tok].pre && !n->end)
 			child = (*mdocs[n->tok].pre)(m, n, h);
 		break;
 	}
@@ -453,7 +453,7 @@ print_mdoc_node(MDOC_ARGS)
 		mdoc_root_post(m, n, h);
 		break;
 	default:
-		if (mdocs[n->tok].post)
+		if (mdocs[n->tok].post && !n->end)
 			(*mdocs[n->tok].post)(m, n, h);
 		break;
 	}
diff --git a/mdoc_macro.c b/mdoc_macro.c
index 51c852a0..6e9b07e8 100644
--- a/mdoc_macro.c
+++ b/mdoc_macro.c
@@ -1,4 +1,4 @@
-/*	$Id: mdoc_macro.c,v 1.82 2010/06/27 15:52:41 kristaps Exp $ */
+/*	$Id: mdoc_macro.c,v 1.83 2010/06/29 19:20:38 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -50,6 +50,8 @@ static	int	  	append_delims(struct mdoc *,
 				int, int *, char *);
 static	enum mdoct	lookup(enum mdoct, const char *);
 static	enum mdoct	lookup_raw(const char *);
+static	int		make_pending(struct mdoc_node *, enum mdoc_type,
+				struct mdoc *, int, int);
 static	int	  	phrase(struct mdoc *, int, int, char *);
 static	enum mdoct 	rew_alt(enum mdoct);
 static	int	  	rew_dobreak(enum mdoct, 
@@ -61,8 +63,6 @@ static	int	  	rew_last(struct mdoc *,
 				const struct mdoc_node *);
 static	int	  	rew_sub(enum mdoc_type, struct mdoc *, 
 				enum mdoct, int, int);
-static	int	  	swarn(struct mdoc *, enum mdoc_type, int, 
-				int, const struct mdoc_node *);
 
 const	struct mdoc_macro __mdoc_macros[MDOC_MAX] = {
 	{ in_line_argn, MDOC_CALLABLE | MDOC_PARSED }, /* Ap */
@@ -192,53 +192,6 @@ const	struct mdoc_macro __mdoc_macros[MDOC_MAX] = {
 const	struct mdoc_macro * const mdoc_macros = __mdoc_macros;
 
 
-static int
-swarn(struct mdoc *mdoc, enum mdoc_type type, 
-		int line, int pos, const struct mdoc_node *p)
-{
-	const char	*n, *t, *tt;
-	enum mandocerr	 ec;
-
-	n = t = "<root>";
-	tt = "block";
-
-	switch (type) {
-	case (MDOC_BODY):
-		tt = "multi-line";
-		break;
-	case (MDOC_HEAD):
-		tt = "line";
-		break;
-	default:
-		break;
-	}
-
-	switch (p->type) {
-	case (MDOC_BLOCK):
-		n = mdoc_macronames[p->tok];
-		t = "block";
-		break;
-	case (MDOC_BODY):
-		n = mdoc_macronames[p->tok];
-		t = "multi-line";
-		break;
-	case (MDOC_HEAD):
-		n = mdoc_macronames[p->tok];
-		t = "line";
-		break;
-	default:
-		break;
-	}
-
-	ec = (MDOC_IGN_SCOPE & mdoc->pflags) ?
-		MANDOCERR_SCOPE : MANDOCERR_SYNTSCOPE;
-
-	return(mdoc_vmsg(mdoc, ec, line, pos, 
-				"%s scope breaks %s of %s", 
-				tt, t, n));
-}
-
-
 /*
  * This is called at the end of parsing.  It must traverse up the tree,
  * closing out open [implicit] scopes.  Obviously, open explicit scopes
@@ -410,7 +363,11 @@ rew_dohalt(enum mdoct tok, enum mdoc_type type,
 		/* FALLTHROUGH */
 	case (MDOC_Vt):
 		assert(MDOC_TAIL != type);
-		if (type == p->type && tok == p->tok)
+		if (tok != p->tok)
+			break;
+		if (p->end)
+			return(REWIND_HALT);
+		if (type == p->type)
 			return(REWIND_REWIND);
 		break;
 	case (MDOC_It):
@@ -464,7 +421,11 @@ rew_dohalt(enum mdoct tok, enum mdoc_type type,
 	case (MDOC_So):
 		/* FALLTHROUGH */
 	case (MDOC_Xo):
-		if (type == p->type && tok == p->tok)
+		if (tok != p->tok)
+			break;
+		if (p->end)
+			return(REWIND_HALT);
+		if (type == p->type)
 			return(REWIND_REWIND);
 		break;
 	/* Multi-line explicit scope close. */
@@ -499,7 +460,11 @@ rew_dohalt(enum mdoct tok, enum mdoc_type type,
 	case (MDOC_Sc):
 		/* FALLTHROUGH */
 	case (MDOC_Xc):
-		if (type == p->type && rew_alt(tok) == p->tok)
+		if (rew_alt(tok) != p->tok)
+			break;
+		if (p->end)
+			return(REWIND_HALT);
+		if (type == p->type)
 			return(REWIND_REWIND);
 		break;
 	default:
@@ -526,6 +491,8 @@ rew_dobreak(enum mdoct tok, const struct mdoc_node *p)
 		return(1);
 	if (MDOC_VALID & p->flags)
 		return(1);
+	if (MDOC_BODY == p->type && p->end)
+		return(1);
 
 	switch (tok) {
 	case (MDOC_It):
@@ -576,6 +543,83 @@ rew_elem(struct mdoc *mdoc, enum mdoct tok)
 }
 
 
+/*
+ * We are trying to close a block identified by tok,
+ * but the child block *broken is still open.
+ * Thus, postpone closing the tok block
+ * until the rew_sub call closing *broken.
+ */
+static int
+make_pending(struct mdoc_node *broken, enum mdoct tok,
+		struct mdoc *m, int line, int ppos)
+{
+	struct mdoc_node *breaker;
+
+	/*
+	 * Iterate backwards, searching for the block matching tok,
+	 * that is, the block breaking the *broken block.
+	 */
+	for (breaker = broken->parent; breaker; breaker = breaker->parent) {
+
+		/*
+		 * If the *broken block had already been broken before
+		 * and we encounter its breaker, make the tok block
+		 * pending on the inner breaker.
+		 * Graphically, "[A breaker=[B broken=[C->B B] tok=A] C]"
+		 * becomes "[A broken=[B [C->B B] tok=A] C]"
+		 * and finally "[A [B->A [C->B B] A] C]".
+		 */
+		if (breaker == broken->pending) {
+			broken = breaker;
+			continue;
+		}
+
+		if (REWIND_REWIND != rew_dohalt(tok, MDOC_BLOCK, breaker))
+			continue;
+		if (MDOC_BODY == broken->type)
+			broken = broken->parent;
+
+		/*
+		 * Found the breaker.
+		 * If another, outer breaker is already pending on
+		 * the *broken block, we must not clobber the link
+		 * to the outer breaker, but make it pending on the
+		 * new, now inner breaker.
+		 * Graphically, "[A breaker=[B broken=[C->A A] tok=B] C]"
+		 * becomes "[A breaker=[B->A broken=[C A] tok=B] C]"
+		 * and finally "[A [B->A [C->B A] B] C]".
+		 */
+		if (broken->pending) {
+			struct mdoc_node *taker;
+
+			/*
+			 * If the breaker had also been broken before,
+			 * it cannot take on the outer breaker itself,
+			 * but must hand it on to its own breakers.
+			 * Graphically, this is the following situation:
+			 * "[A [B breaker=[C->B B] broken=[D->A A] tok=C] D]"
+			 * "[A taker=[B->A breaker=[C->B B] [D->C A] C] D]"
+			 */
+			taker = breaker;
+			while (taker->pending)
+				taker = taker->pending;
+			taker->pending = broken->pending;
+		}
+		broken->pending = breaker;
+		mdoc_vmsg(m, MANDOCERR_SCOPE, line, ppos, "%s breaks %s",
+		    mdoc_macronames[tok], mdoc_macronames[broken->tok]);
+		return(1);
+	}
+
+	/*
+	 * Found no matching block for tok.
+	 * Are you trying to close a block that is not open?
+	 * Report failure and abort the parser.
+	 */
+	mdoc_pmsg(m, line, ppos, MANDOCERR_SYNTNOSCOPE);
+	return(0);
+}
+
 static int
 rew_sub(enum mdoc_type t, struct mdoc *m, 
 		enum mdoct tok, int line, int ppos)
@@ -587,7 +631,7 @@ rew_sub(enum mdoc_type t, struct mdoc *m,
 	for (n = m->last; n; n = n->parent) {
 		c = rew_dohalt(tok, t, n);
 		if (REWIND_HALT == c) {
-			if (MDOC_BLOCK != t)
+			if (n->end || MDOC_BLOCK != t)
 				return(1);
 			if ( ! (MDOC_EXPLICIT & mdoc_macros[tok].flags))
 				return(1);
@@ -599,8 +643,7 @@ rew_sub(enum mdoc_type t, struct mdoc *m,
 			break;
 		else if (rew_dobreak(tok, n))
 			continue;
-		if ( ! swarn(m, t, line, ppos, n))
-			return(0);
+		return(make_pending(n, tok, m, line, ppos));
 	}
 
 	assert(n);
@@ -608,15 +651,14 @@ rew_sub(enum mdoc_type t, struct mdoc *m,
 		return(0);
 
 	/*
-	 * The current block extends an enclosing block beyond a line
-	 * break.  Now that the current block ends, close the enclosing
-	 * block, too.
+	 * The current block extends an enclosing block.
+	 * Now that the current block ends, close the enclosing block, too.
 	 */
-	if (NULL != (n = n->pending)) {
-		assert(MDOC_HEAD == n->type);
+	while (NULL != (n = n->pending)) {
 		if ( ! rew_last(m, n))
 			return(0);
-		if ( ! mdoc_body_alloc(m, n->line, n->pos, n->tok))
+		if (MDOC_HEAD == n->type &&
+		    ! mdoc_body_alloc(m, n->line, n->pos, n->tok))
 			return(0);
 	}
 
@@ -672,9 +714,13 @@ append_delims(struct mdoc *m, int line, int *pos, char *buf)
 static int
 blk_exp_close(MACRO_PROT_ARGS)
 {
+	struct mdoc_node *body;		/* Our own body. */
+	struct mdoc_node *later;	/* A sub-block starting later. */
+	struct mdoc_node *n;		/* For searching backwards. */
+
 	int	 	 j, lastarg, maxargs, flushed, nl;
 	enum margserr	 ac;
-	enum mdoct	 ntok;
+	enum mdoct	 atok, ntok;
 	char		*p;
 
 	nl = MDOC_NEWLINE & m->flags;
@@ -688,6 +734,68 @@ blk_exp_close(MACRO_PROT_ARGS)
 		break;
 	}
 
+	/*
+	 * Search backwards for beginnings of blocks,
+	 * both of our own and of pending sub-blocks.
+	 */
+	atok = rew_alt(tok);
+	body = later = NULL;
+	for (n = m->last; n; n = n->parent) {
+		if (MDOC_VALID & n->flags)
+			continue;
+
+		/* Remember the start of our own body. */
+		if (MDOC_BODY == n->type && atok == n->tok) {
+			if ( ! n->end)
+				body = n;
+			continue;
+		}
+
+		if (MDOC_BLOCK != n->type)
+			continue;
+		if (atok == n->tok) {
+			assert(body);
+
+			/*
+			 * Found the start of our own block.
+			 * When there is no pending sub block,
+			 * just proceed to closing out.
+			 */
+			if (NULL == later)
+				break;
+
+			/* 
+			 * When there is a pending sub block,
+			 * postpone closing out the current block
+			 * until the rew_sub() closing out the sub-block.
+			 */
+			if ( ! make_pending(later, tok, m, line, ppos))
+				return(0);
+
+			/*
+			 * Mark the place where the formatting - but not
+			 * the scope - of the current block ends.
+			 */
+			if ( ! mdoc_endbody_alloc(m, line, ppos,
+			    atok, body, ENDBODY_SPACE))
+				return(0);
+			break;
+		}
+
+		/*
+		 * When finding an open sub block, remember the last
+		 * open explicit block, or, in case there are only
+		 * implicit ones, the first open implicit block.
+		 */
+		if (later &&
+		    MDOC_EXPLICIT & mdoc_macros[later->tok].flags)
+			continue;
+		if (MDOC_CALLABLE & mdoc_macros[n->tok].flags) {
+			assert( ! (MDOC_ACTED & n->flags));
+			later = n;
+		}
+	}
+
 	if ( ! (MDOC_CALLABLE & mdoc_macros[tok].flags)) {
 		/* FIXME: do this in validate */
 		if (buf[*pos]) 
@@ -702,7 +810,7 @@ blk_exp_close(MACRO_PROT_ARGS)
 	if ( ! rew_sub(MDOC_BODY, m, tok, line, ppos))
 		return(0);
 
-	if (maxargs > 0) 
+	if (NULL == later && maxargs > 0) 
 		if ( ! mdoc_tail_alloc(m, line, ppos, rew_alt(tok)))
 			return(0);
 
@@ -1255,22 +1363,36 @@ blk_part_imp(MACRO_PROT_ARGS)
 		body->parent->flags |= MDOC_EOS;
 	}
 
+	/*
+	 * If there is an open sub-block requiring explicit close-out,
+	 * postpone closing out the current block
+	 * until the rew_sub() call closing out the sub-block.
+	 */
+	for (n = m->last; n && n != body && n != blk->parent; n = n->parent) {
+		if (MDOC_BLOCK == n->type &&
+		    MDOC_EXPLICIT & mdoc_macros[n->tok].flags &&
+		    ! (MDOC_VALID & n->flags)) {
+			assert( ! (MDOC_ACTED & n->flags));
+			if ( ! make_pending(n, tok, m, line, ppos))
+				return(0);
+			if ( ! mdoc_endbody_alloc(m, line, ppos,
+			    tok, body, ENDBODY_NOSPACE))
+				return(0);
+			return(1);
+		}
+	}
+
 	/* 
 	 * If we can't rewind to our body, then our scope has already
 	 * been closed by another macro (like `Oc' closing `Op').  This
 	 * is ugly behaviour nodding its head to OpenBSD's overwhelming
 	 * crufty use of `Op' breakage.
-	 *
-	 * FIXME - this should be ifdef'd OpenBSD?
 	 */
-	for (n = m->last; n; n = n->parent)
-		if (body == n)
-			break;
-
-	if (NULL == n && ! mdoc_nmsg(m, body, MANDOCERR_SCOPE))
+	if (n != body && ! mdoc_vmsg(m, MANDOCERR_SCOPE, line, ppos,
+	    "%s broken", mdoc_macronames[tok]))
 		return(0);
 
-	if (n && ! rew_last(m, body))
+	if (n && ! rew_sub(MDOC_BODY, m, tok, line, ppos))
 		return(0);
 
 	/* Standard appending of delimiters. */
@@ -1280,7 +1402,7 @@ blk_part_imp(MACRO_PROT_ARGS)
 
 	/* Rewind scope, if applicable. */
 
-	if (n && ! rew_last(m, blk))
+	if (n && ! rew_sub(MDOC_BLOCK, m, tok, line, ppos))
 		return(0);
 
 	return(1);
diff --git a/mdoc_term.c b/mdoc_term.c
index 33cfaac4..6995bba1 100644
--- a/mdoc_term.c
+++ b/mdoc_term.c
@@ -1,4 +1,4 @@
-/*	$Id: mdoc_term.c,v 1.161 2010/06/27 17:53:27 schwarze Exp $ */
+/*	$Id: mdoc_term.c,v 1.162 2010/06/29 19:20:38 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -325,20 +325,37 @@ print_mdoc_node(DECL_ARGS)
 	memset(&npair, 0, sizeof(struct termpair));
 	npair.ppair = pair;
 
-	if (MDOC_TEXT != n->type) {
-		if (termacts[n->tok].pre)
-			chld = (*termacts[n->tok].pre)(p, &npair, m, n);
-	} else 
+	if (MDOC_TEXT == n->type)
 		term_word(p, n->string); 
+	else if (termacts[n->tok].pre && !n->end)
+		chld = (*termacts[n->tok].pre)(p, &npair, m, n);
 
 	if (chld && n->child)
 		print_mdoc_nodelist(p, &npair, m, n->child);
 
 	term_fontpopq(p, font);
 
-	if (MDOC_TEXT != n->type)
-		if (termacts[n->tok].post)
-			(*termacts[n->tok].post)(p, &npair, m, n);
+	if (MDOC_TEXT != n->type &&
+	    termacts[n->tok].post &&
+	    ! (MDOC_ENDED & n->flags)) {
+		(*termacts[n->tok].post)(p, &npair, m, n);
+
+		/*
+		 * Explicit end tokens not only call the post
+		 * handler, but also tell the respective block
+		 * that it must not call the post handler again.
+		 */
+		if (n->end)
+			n->pending->flags |= MDOC_ENDED;
+
+		/*
+		 * End of line terminating an implicit block
+		 * while an explicit block is still open.
+		 * Continue the explicit block without spacing.
+		 */
+		if (ENDBODY_NOSPACE == n->end)
+			p->flags |= TERMP_NOSPACE;
+	}
 
 	if (MDOC_EOS & n->flags)
 		p->flags |= TERMP_SENTENCE;
diff --git a/tree.c b/tree.c
index 61ce1b4f..09bc87e6 100644
--- a/tree.c
+++ b/tree.c
@@ -1,4 +1,4 @@
-/*	$Id: tree.c,v 1.22 2010/06/26 15:36:37 kristaps Exp $ */
+/*	$Id: tree.c,v 1.23 2010/06/29 19:20:38 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -75,7 +75,10 @@ print_mdoc(const struct mdoc_node *n, int indent)
 		t = "block-head";
 		break;
 	case (MDOC_BODY):
-		t = "block-body";
+		if (n->end)
+			t = "body-end";
+		else
+			t = "block-body";
 		break;
 	case (MDOC_TAIL):
 		t = "block-tail";