===================================================================
RCS file: /cvs/mandoc/roff.c,v
retrieving revision 1.75
retrieving revision 1.88
diff -u -p -r1.75 -r1.88
--- mandoc/roff.c	2010/05/16 13:49:23	1.75
+++ mandoc/roff.c	2010/06/10 21:42:02	1.88
@@ -1,4 +1,4 @@
-/*	$Id: roff.c,v 1.75 2010/05/16 13:49:23 kristaps Exp $ */
+/*	$Id: roff.c,v 1.88 2010/06/10 21:42:02 kristaps Exp $ */
 /*
  * Copyright (c) 2010 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -19,6 +19,7 @@
 #endif
 
 #include <assert.h>
+#include <ctype.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
@@ -26,44 +27,59 @@
 #include "mandoc.h"
 #include "roff.h"
 
+#define	RSTACK_MAX	128
+
 #define	ROFF_CTL(c) \
 	('.' == (c) || '\'' == (c))
-#ifdef	ROFF_DEBUG
-#define	ROFF_MDEBUG(p, str) \
-	fprintf(stderr, "%s: %s (%d:%d)\n", (str), \
-		roffs[(p)->last->tok].name, \
-	       	(p)->last->line, (p)->last->col)
+
+#if 1
+#define	ROFF_DEBUG(fmt, args...) \
+	do { /* Nothing. */ } while (/*CONSTCOND*/ 0)
 #else
-#define	ROFF_MDEBUG(p, str) while (/* CONSTCOND */ 0)
+#define	ROFF_DEBUG(fmt, args...) \
+	do { fprintf(stderr, fmt , ##args); } while (/*CONSTCOND*/ 0)
 #endif
 
 enum	rofft {
-	ROFF_if,
-	ROFF_ccond,
-#if 0
 	ROFF_am,
 	ROFF_ami,
+	ROFF_am1,
 	ROFF_de,
 	ROFF_dei,
+	ROFF_de1,
+	ROFF_ds,
+	ROFF_el,
+	ROFF_ie,
+	ROFF_if,
 	ROFF_ig,
-	ROFF_close,
-#endif
+	ROFF_rm,
+	ROFF_tr,
+	ROFF_cblock,
+	ROFF_ccond,
 	ROFF_MAX
 };
 
+enum	roffrule {
+	ROFFRULE_ALLOW,
+	ROFFRULE_DENY
+};
+
 struct	roff {
 	struct roffnode	*last; /* leaf of stack */
 	mandocmsg	 msg; /* err/warn/fatal messages */
 	void		*data; /* privdata for messages */
+	enum roffrule	 rstack[RSTACK_MAX]; /* stack of !`ie' rules */
+	int		 rstackpos; /* position in rstack */
 };
 
 struct	roffnode {
 	enum rofft	 tok; /* type of node */
 	struct roffnode	*parent; /* up one in stack */
-	char		*end; /* end-token: custom */
 	int		 line; /* parse line */
 	int		 col; /* parse col */
-	int		 endspan;
+	char		*end; /* end-rules: custom token */
+	int		 endspan; /* end-rules: next-line or infty */
+	enum roffrule	 rule; /* current evaluation rule */
 };
 
 #define	ROFF_ARGS	 struct roff *r, /* parse ctx */ \
@@ -79,38 +95,85 @@ typedef	enum rofferr (*roffproc)(ROFF_ARGS);
 
 struct	roffmac {
 	const char	*name; /* macro name */
-	roffproc	 proc;
+	roffproc	 proc; /* process new macro */
+	roffproc	 text; /* process as child text of macro */
+	roffproc	 sub; /* process as child of macro */
+	int		 flags;
+#define	ROFFMAC_STRUCT	(1 << 0) /* always interpret */
+	struct roffmac	*next;
 };
 
-static	enum rofferr	 roff_if(ROFF_ARGS);
+static	enum rofferr	 roff_block(ROFF_ARGS);
+static	enum rofferr	 roff_block_text(ROFF_ARGS);
+static	enum rofferr	 roff_block_sub(ROFF_ARGS);
+static	enum rofferr	 roff_cblock(ROFF_ARGS);
 static	enum rofferr	 roff_ccond(ROFF_ARGS);
-#if 0
-static	enum rofferr	 roff_new_close(ROFF_ARGS);
-static	enum rofferr	 roff_new_ig(ROFF_ARGS);
-static	enum rofferr	 roff_sub_ig(ROFF_ARGS);
-#endif
+static	enum rofferr	 roff_cond(ROFF_ARGS);
+static	enum rofferr	 roff_cond_text(ROFF_ARGS);
+static	enum rofferr	 roff_cond_sub(ROFF_ARGS);
+static	enum roffrule	 roff_evalcond(const char *, int *);
+static	enum rofferr	 roff_line(ROFF_ARGS);
 
-const	struct roffmac	 roffs[ROFF_MAX] = {
-	{ "if", roff_if },
-	{ "\\}", roff_ccond },
-#if 0
-	{ "am", roff_sub_ig, roff_new_ig },
-	{ "ami", roff_sub_ig, roff_new_ig },
-	{ "de", roff_sub_ig, roff_new_ig },
-	{ "dei", roff_sub_ig, roff_new_ig },
-	{ "ig", roff_sub_ig, roff_new_ig },
-	{ ".", NULL, roff_new_close },
-#endif
+/* See roff_hash_find() */
+
+#define	ASCII_HI	 126
+#define	ASCII_LO	 33
+#define	HASHWIDTH	(ASCII_HI - ASCII_LO + 1)
+
+static	struct roffmac	*hash[HASHWIDTH];
+
+static	struct roffmac	 roffs[ROFF_MAX] = {
+	{ "am", roff_block, roff_block_text, roff_block_sub, 0, NULL },
+	{ "ami", roff_block, roff_block_text, roff_block_sub, 0, NULL },
+	{ "am1", roff_block, roff_block_text, roff_block_sub, 0, NULL },
+	{ "de", roff_block, roff_block_text, roff_block_sub, 0, NULL },
+	{ "dei", roff_block, roff_block_text, roff_block_sub, 0, NULL },
+	{ "de1", roff_block, roff_block_text, roff_block_sub, 0, NULL },
+	{ "ds", roff_line, NULL, NULL, 0, NULL },
+	{ "el", roff_cond, roff_cond_text, roff_cond_sub, ROFFMAC_STRUCT, NULL },
+	{ "ie", roff_cond, roff_cond_text, roff_cond_sub, ROFFMAC_STRUCT, NULL },
+	{ "if", roff_cond, roff_cond_text, roff_cond_sub, ROFFMAC_STRUCT, NULL },
+	{ "ig", roff_block, roff_block_text, roff_block_sub, 0, NULL },
+	{ "rm", roff_line, NULL, NULL, 0, NULL },
+	{ "tr", roff_line, NULL, NULL, 0, NULL },
+	{ ".", roff_cblock, NULL, NULL, 0, NULL },
+	{ "\\}", roff_ccond, NULL, NULL, 0, NULL },
 };
 
 static	void		 roff_free1(struct roff *);
 static	enum rofft	 roff_hash_find(const char *);
+static	void		 roff_hash_init(void);
+static	void		 roffnode_cleanscope(struct roff *);
 static	int		 roffnode_push(struct roff *, 
 				enum rofft, int, int);
 static	void		 roffnode_pop(struct roff *);
 static	enum rofft	 roff_parse(const char *, int *);
 
+/* See roff_hash_find() */
+#define	ROFF_HASH(p)	(p[0] - ASCII_LO)
 
+static void
+roff_hash_init(void)
+{
+	struct roffmac	 *n;
+	int		  buc, i;
+
+	for (i = 0; i < (int)ROFF_MAX; i++) {
+		assert(roffs[i].name[0] >= ASCII_LO);
+		assert(roffs[i].name[0] <= ASCII_HI);
+
+		buc = ROFF_HASH(roffs[i].name);
+
+		if (NULL != (n = hash[buc])) {
+			for ( ; n->next; n = n->next)
+				/* Do nothing. */ ;
+			n->next = &roffs[i];
+		} else
+			hash[buc] = &roffs[i];
+	}
+}
+
+
 /*
  * Look up a roff token by its name.  Returns ROFF_MAX if no macro by
  * the nil-terminated string name could be found.
@@ -118,14 +181,27 @@ static	enum rofft	 roff_parse(const char *, int *);
 static enum rofft
 roff_hash_find(const char *p)
 {
-	int		 i;
+	int		 buc;
+	struct roffmac	*n;
 
-	/* FIXME: make this be fast and efficient. */
+	/*
+	 * libroff has an extremely simple hashtable, for the time
+	 * being, which simply keys on the first character, which must
+	 * be printable, then walks a chain.  It works well enough until
+	 * optimised.
+	 */
 
-	for (i = 0; i < (int)ROFF_MAX; i++)
-		if (0 == strcmp(roffs[i].name, p))
-			return((enum rofft)i);
+	if (p[0] < ASCII_LO || p[0] > ASCII_HI)
+		return(ROFF_MAX);
 
+	buc = ROFF_HASH(p);
+
+	if (NULL == (n = hash[buc]))
+		return(ROFF_MAX);
+	for ( ; n; n = n->next)
+		if (0 == strcmp(n->name, p))
+			return((enum rofft)(n - roffs));
+
 	return(ROFF_MAX);
 }
 
@@ -141,6 +217,11 @@ roffnode_pop(struct roff *r)
 
 	assert(r->last);
 	p = r->last; 
+
+	if (ROFF_el == p->tok)
+		if (r->rstackpos > -1)
+			r->rstackpos--;
+
 	r->last = r->last->parent;
 	if (p->end)
 		free(p->end);
@@ -166,6 +247,7 @@ roffnode_push(struct roff *r, enum rofft tok, int line
 	p->parent = r->last;
 	p->line = line;
 	p->col = col;
+	p->rule = p->parent ? p->parent->rule : ROFFRULE_DENY;
 
 	r->last = p;
 	return(1);
@@ -210,6 +292,9 @@ roff_alloc(const mandocmsg msg, void *data)
 
 	r->msg = msg;
 	r->data = data;
+	r->rstackpos = -1;
+	
+	roff_hash_init();
 	return(r);
 }
 
@@ -221,28 +306,57 @@ roff_parseln(struct roff *r, int ln, 
 	enum rofft	 t;
 	int		 ppos;
 
-	/* Return when in free text without a context. */
+	/*
+	 * First, if a scope is open and we're not a macro, pass the
+	 * text through the macro's filter.  If a scope isn't open and
+	 * we're not a macro, just let it through.
+	 */
 
 	if (r->last && ! ROFF_CTL((*bufp)[pos])) {
-		/* XXX: this assumes we're just discarding. */
-		while (r->last) {
-			if (r->last->endspan-- < 0)
-				break;
-			ROFF_MDEBUG(r, "closing implicit scope");
-			roffnode_pop(r);
-		}
-		return(ROFF_IGN);
-	} else if ( ! ROFF_CTL((*bufp)[pos]))
+		t = r->last->tok;
+		assert(roffs[t].text);
+		ROFF_DEBUG("roff: intercept scoped text: %s, [%s]\n", 
+				roffs[t].name, &(*bufp)[pos]);
+		return((*roffs[t].text)
+				(r, t, bufp, szp, ln, pos, pos, offs));
+	} else if ( ! ROFF_CTL((*bufp)[pos])) {
+		ROFF_DEBUG("roff: pass non-scoped text: [%s]\n", 
+				&(*bufp)[pos]);
 		return(ROFF_CONT);
+	}
 
-	/* There's nothing on the stack: make us anew. */
+	/*
+	 * If a scope is open, go to the child handler for that macro,
+	 * as it may want to preprocess before doing anything with it.
+	 */
 
+	if (r->last) {
+		t = r->last->tok;
+		assert(roffs[t].sub);
+		ROFF_DEBUG("roff: intercept scoped context: %s\n", 
+				roffs[t].name);
+		return((*roffs[t].sub)
+				(r, t, bufp, szp, ln, pos, pos, offs));
+	}
+
+	/*
+	 * Lastly, as we've no scope open, try to look up and execute
+	 * the new macro.  If no macro is found, simply return and let
+	 * the compilers handle it.
+	 */
+
 	ppos = pos;
-	if (ROFF_MAX == (t = roff_parse(*bufp, &pos)))
+	if (ROFF_MAX == (t = roff_parse(*bufp, &pos))) {
+		ROFF_DEBUG("roff: pass non-scoped non-macro: [%s]\n", 
+				&(*bufp)[pos]);
 		return(ROFF_CONT);
+	}
 
+	ROFF_DEBUG("roff: intercept new-scope: %s, [%s]\n", 
+			roffs[t].name, &(*bufp)[pos]);
 	assert(roffs[t].proc);
-	return((*roffs[t].proc)(r, t, bufp, szp, ln, ppos, pos, offs));
+	return((*roffs[t].proc)
+			(r, t, bufp, szp, ln, ppos, pos, offs));
 }
 
 
@@ -280,7 +394,7 @@ roff_parse(const char *buf, int *pos)
 	for (j = 0; j < 4; j++, (*pos)++)
 		if ('\0' == (mac[j] = buf[*pos]))
 			break;
-		else if (' ' == buf[*pos])
+		else if (' ' == buf[*pos] || (j && '\\' == buf[*pos]))
 			break;
 
 	if (j == 4 || j < 1)
@@ -298,181 +412,434 @@ roff_parse(const char *buf, int *pos)
 }
 
 
-#if 0
 /* ARGSUSED */
 static enum rofferr
-roff_sub_ig(ROFF_ARGS)
+roff_cblock(ROFF_ARGS)
 {
-	int		 i, j;
 
-	/* Ignore free-text lines. */
+	/*
+	 * A block-close `..' should only be invoked as a child of an
+	 * ignore macro, otherwise raise a warning and just ignore it.
+	 */
 
-	if ('.' != (*bufp)[ppos] && '\'' != (*bufp)[ppos])
+	if (NULL == r->last) {
+		if ( ! (*r->msg)(MANDOCERR_NOSCOPE, r->data, ln, ppos, NULL))
+			return(ROFF_ERR);
 		return(ROFF_IGN);
+	}
 
-	if (r->last->end) {
-		i = ppos + 1;
+	switch (r->last->tok) {
+	case (ROFF_am):
+		/* FALLTHROUGH */
+	case (ROFF_ami):
+		/* FALLTHROUGH */
+	case (ROFF_am1):
+		/* FALLTHROUGH */
+	case (ROFF_de):
+		/* FALLTHROUGH */
+	case (ROFF_dei):
+		/* FALLTHROUGH */
+	case (ROFF_de1):
+		/* FALLTHROUGH */
+	case (ROFF_ig):
+		break;
+	default:
+		if ( ! (*r->msg)(MANDOCERR_NOSCOPE, r->data, ln, ppos, NULL))
+			return(ROFF_ERR);
+		return(ROFF_IGN);
+	}
 
-		while ((*bufp)[i] && ' ' == (*bufp)[i])
-			i++;
+	if ((*bufp)[pos])
+		if ( ! (*r->msg)(MANDOCERR_ARGSLOST, r->data, ln, pos, NULL))
+			return(ROFF_ERR);
 
-		for (j = 0; r->last->end[j]; i++, j++)
-			if ((*bufp)[i] != r->last->end[j])
-				return(ROFF_IGN);
+	roffnode_pop(r);
+	roffnode_cleanscope(r);
+	return(ROFF_IGN);
 
-		if (r->last->end[j])
-			return(ROFF_IGN);
-		if ((*bufp)[i] && ' ' != (*bufp)[i])
-			return(ROFF_IGN);
+}
 
-		while (' ' == (*bufp)[i])
-			i++;
 
-	} else if (ROFF_close != roff_parse(*bufp, &i))
+static void
+roffnode_cleanscope(struct roff *r)
+{
+
+	while (r->last) {
+		if (--r->last->endspan < 0)
+			break;
+		roffnode_pop(r);
+	}
+}
+
+
+/* ARGSUSED */
+static enum rofferr
+roff_ccond(ROFF_ARGS)
+{
+
+	if (NULL == r->last) {
+		if ( ! (*r->msg)(MANDOCERR_NOSCOPE, r->data, ln, ppos, NULL))
+			return(ROFF_ERR);
 		return(ROFF_IGN);
+	}
 
-	roffnode_pop(r);
+	switch (r->last->tok) {
+	case (ROFF_el):
+		/* FALLTHROUGH */
+	case (ROFF_ie):
+		/* FALLTHROUGH */
+	case (ROFF_if):
+		break;
+	default:
+		if ( ! (*r->msg)(MANDOCERR_NOSCOPE, r->data, ln, ppos, NULL))
+			return(ROFF_ERR);
+		return(ROFF_IGN);
+	}
 
-	if ('\0' == (*bufp)[i])
+	if (r->last->endspan > -1) {
+		if ( ! (*r->msg)(MANDOCERR_NOSCOPE, r->data, ln, ppos, NULL))
+			return(ROFF_ERR);
 		return(ROFF_IGN);
-	if ( ! (*r->msg)(MANDOCERR_ARGSLOST, r->data, ln, i, NULL))
-		return(ROFF_ERR);
+	}
 
+	if ((*bufp)[pos])
+		if ( ! (*r->msg)(MANDOCERR_ARGSLOST, r->data, ln, pos, NULL))
+			return(ROFF_ERR);
+
+	roffnode_pop(r);
+	roffnode_cleanscope(r);
 	return(ROFF_IGN);
 }
 
 
 /* ARGSUSED */
 static enum rofferr
-roff_new_close(ROFF_ARGS)
+roff_block(ROFF_ARGS)
 {
+	int		sv;
+	size_t		sz;
 
-	if ( ! (*r->msg)(MANDOCERR_NOSCOPE, r->data, ln, ppos, NULL))
+	if (ROFF_ig != tok && '\0' == (*bufp)[pos]) {
+		if ( ! (*r->msg)(MANDOCERR_NOARGS, r->data, ln, ppos, NULL))
+			return(ROFF_ERR);
+		return(ROFF_IGN);
+	} else if (ROFF_ig != tok) {
+		while ((*bufp)[pos] && ' ' != (*bufp)[pos])
+			pos++;
+		while (' ' == (*bufp)[pos])
+			pos++;
+	}
+
+	if ( ! roffnode_push(r, tok, ln, ppos))
 		return(ROFF_ERR);
 
+	if ('\0' == (*bufp)[pos])
+		return(ROFF_IGN);
+
+	sv = pos;
+	while ((*bufp)[pos] && ' ' != (*bufp)[pos] && 
+			'\t' != (*bufp)[pos])
+		pos++;
+
+	/*
+	 * Note: groff does NOT like escape characters in the input.
+	 * Instead of detecting this, we're just going to let it fly and
+	 * to hell with it.
+	 */
+
+	assert(pos > sv);
+	sz = (size_t)(pos - sv);
+
+	if (1 == sz && '.' == (*bufp)[sv])
+		return(ROFF_IGN);
+
+	r->last->end = malloc(sz + 1);
+
+	if (NULL == r->last->end) {
+		(*r->msg)(MANDOCERR_MEM, r->data, ln, pos, NULL);
+		return(ROFF_ERR);
+	}
+
+	memcpy(r->last->end, *bufp + sv, sz);
+	r->last->end[(int)sz] = '\0';
+
+	if ((*bufp)[pos])
+		if ( ! (*r->msg)(MANDOCERR_ARGSLOST, r->data, ln, pos, NULL))
+			return(ROFF_ERR);
+
 	return(ROFF_IGN);
 }
-#endif
 
 
 /* ARGSUSED */
 static enum rofferr
-roff_ccond(ROFF_ARGS)
+roff_block_sub(ROFF_ARGS)
 {
+	enum rofft	t;
+	int		i, j;
 
-	if (NULL == r->last || ROFF_if != r->last->tok || r->last->endspan > -1) {
-		if ( ! (*r->msg)(MANDOCERR_NOSCOPE, r->data, ln, ppos, NULL))
-			return(ROFF_ERR);
-		return(ROFF_IGN);
-	}
+	/*
+	 * First check whether a custom macro exists at this level.  If
+	 * it does, then check against it.  This is some of groff's
+	 * stranger behaviours.  If we encountered a custom end-scope
+	 * tag and that tag also happens to be a "real" macro, then we
+	 * need to try interpreting it again as a real macro.  If it's
+	 * not, then return ignore.  Else continue.
+	 */
 
-	ROFF_MDEBUG(r, "closing explicit scope");
-	roffnode_pop(r);
+	if (r->last->end) {
+		i = pos + 1;
+		while (' ' == (*bufp)[i] || '\t' == (*bufp)[i])
+			i++;
 
-	while (r->last) {
-		if (--r->last->endspan < 0)
-			break;
+		for (j = 0; r->last->end[j]; j++, i++)
+			if ((*bufp)[i] != r->last->end[j])
+				break;
 
-		ROFF_MDEBUG(r, "closing implicit scope");
-		roffnode_pop(r);
+		if ('\0' == r->last->end[j] && 
+				('\0' == (*bufp)[i] ||
+				 ' ' == (*bufp)[i] ||
+				 '\t' == (*bufp)[i])) {
+			roffnode_pop(r);
+			roffnode_cleanscope(r);
+
+			if (ROFF_MAX != roff_parse(*bufp, &pos))
+				return(ROFF_RERUN);
+			return(ROFF_IGN);
+		}
 	}
 
+	/*
+	 * If we have no custom end-query or lookup failed, then try
+	 * pulling it out of the hashtable.
+	 */
+
+	ppos = pos;
+	t = roff_parse(*bufp, &pos);
+
+	/* If we're not a comment-end, then throw it away. */
+	if (ROFF_cblock != t)
+		return(ROFF_IGN);
+
+	assert(roffs[t].proc);
+	return((*roffs[t].proc)(r, t, bufp, 
+			szp, ln, ppos, pos, offs));
+}
+
+
+/* ARGSUSED */
+static enum rofferr
+roff_block_text(ROFF_ARGS)
+{
+
 	return(ROFF_IGN);
 }
 
 
 /* ARGSUSED */
 static enum rofferr
-roff_if(ROFF_ARGS)
+roff_cond_sub(ROFF_ARGS)
 {
+	enum rofft	 t;
+	enum roffrule	 rr;
+	struct roffnode	*l;
 
+	ppos = pos;
+	rr = r->last->rule;
+
+	/* 
+	 * Clean out scope.  If we've closed ourselves, then don't
+	 * continue. 
+	 */
+
+	l = r->last;
+	roffnode_cleanscope(r);
+
+	if (l != r->last)
+		return(ROFFRULE_DENY == rr ? ROFF_IGN : ROFF_CONT);
+
+	if (ROFF_MAX == (t = roff_parse(*bufp, &pos)))
+		return(ROFFRULE_DENY == rr ? ROFF_IGN : ROFF_CONT);
+
 	/*
-	 * Read ahead past the conditional.
-	 * FIXME: this does not work, as conditionals don't end on
-	 * whitespace, but are parsed according to a formal grammar.
-	 * It's good enough for now, however.
+	 * A denied conditional must evaluate its children if and only
+	 * if they're either structurally required (such as loops and
+	 * conditionals) or a closing macro.
 	 */
+	if (ROFFRULE_DENY == rr)
+		if ( ! (ROFFMAC_STRUCT & roffs[t].flags))
+			if (ROFF_ccond != t)
+				return(ROFF_IGN);
 
-	if ( ! roffnode_push(r, tok, ln, ppos))
-		return(ROFF_ERR);
+	assert(roffs[t].proc);
+	return((*roffs[t].proc)
+			(r, t, bufp, szp, ln, ppos, pos, offs));
+}
 
-	while ((*bufp)[pos] && ' ' != (*bufp)[pos])
-		pos++;
-	while (' ' == (*bufp)[pos])
-		pos++;
 
-	/* Don't evaluate: just assume NO. */
+/* ARGSUSED */
+static enum rofferr
+roff_cond_text(ROFF_ARGS)
+{
+	char		*ep, *st;
+	enum roffrule	 rr;
 
-	r->last->endspan = 1;
+	rr = r->last->rule;
 
-	if ('\\' == (*bufp)[pos] && '{' == (*bufp)[pos + 1]) {
-		ROFF_MDEBUG(r, "opening explicit scope");
-		r->last->endspan = -1;
-		pos += 2;
-	} else
-		ROFF_MDEBUG(r, "opening implicit scope");
+	/*
+	 * We display the value of the text if out current evaluation
+	 * scope permits us to do so.
+	 */
 
-	if ('\0' == (*bufp)[pos])
-		return(ROFF_IGN);
+	st = &(*bufp)[pos];
+	if (NULL == (ep = strstr(st, "\\}"))) {
+		roffnode_cleanscope(r);
+		return(ROFFRULE_DENY == rr ? ROFF_IGN : ROFF_CONT);
+	}
 
-	*offs = pos;
-	return(ROFF_RERUN);
+	if (ep == st || (ep > st && '\\' != *(ep - 1)))
+		roffnode_pop(r);
+
+	roffnode_cleanscope(r);
+	return(ROFFRULE_DENY == rr ? ROFF_IGN : ROFF_CONT);
 }
 
 
-#if 0
+static enum roffrule
+roff_evalcond(const char *v, int *pos)
+{
+
+	switch (v[*pos]) {
+	case ('n'):
+		(*pos)++;
+		return(ROFFRULE_ALLOW);
+	case ('e'):
+		/* FALLTHROUGH */
+	case ('o'):
+		/* FALLTHROUGH */
+	case ('t'):
+		(*pos)++;
+		return(ROFFRULE_DENY);
+	default:
+		break;
+	}
+
+	while (v[*pos] && ' ' != v[*pos])
+		(*pos)++;
+	return(ROFFRULE_DENY);
+}
+
+
+/* ARGSUSED */
 static enum rofferr
-roff_new_ig(ROFF_ARGS)
+roff_cond(ROFF_ARGS)
 {
-	int		 i;
+	int		 sv;
+	enum roffrule	 rule;
 
-	if ( ! roffnode_push(r, tok, ln, ppos))
+	/* Stack overflow! */
+
+	if (ROFF_ie == tok && r->rstackpos == RSTACK_MAX - 1) {
+		(*r->msg)(MANDOCERR_MEM, r->data, ln, ppos, NULL);
 		return(ROFF_ERR);
-	
+	}
+
+	/* First, evaluate the conditional. */
+
+	if (ROFF_el == tok) {
+		/* 
+		 * An `.el' will get the value of the current rstack
+		 * entry set in prior `ie' calls or defaults to DENY.
+	 	 */
+		if (r->rstackpos < 0)
+			rule = ROFFRULE_DENY;
+		else
+			rule = r->rstack[r->rstackpos];
+	} else
+		rule = roff_evalcond(*bufp, &pos);
+
+	sv = pos;
+
+	while (' ' == (*bufp)[pos])
+		pos++;
+
 	/*
-	 * Other macros (not `ig') using this routine have additional
-	 * crap here that we discard. 
+	 * Roff is weird.  If we have just white-space after the
+	 * conditional, it's considered the BODY and we exit without
+	 * really doing anything.  Warn about this.  It's probably
+	 * wrong.
 	 */
 
-	if (ROFF_ig != tok) {
-		while ((*bufp)[ppos] && ' ' != (*bufp)[ppos])
-			ppos++;
-		while (' ' == (*bufp)[ppos])
-			ppos++;
+	if ('\0' == (*bufp)[pos] && sv != pos) {
+		if ((*r->msg)(MANDOCERR_NOARGS, r->data, ln, ppos, NULL))
+			return(ROFF_IGN);
+		return(ROFF_ERR);
 	}
 
-	i = (int)ppos;
+	if ( ! roffnode_push(r, tok, ln, ppos))
+		return(ROFF_ERR);
 
-	while ((*bufp)[i] && ' ' != (*bufp)[i])
-		i++;
+	r->last->rule = rule;
 
-	if (i == (int)ppos)
-		return(ROFF_IGN);
+	ROFF_DEBUG("roff: cond: %s -> %s\n", roffs[tok].name, 
+			ROFFRULE_ALLOW == rule ?  "allow" : "deny");
 
-	if ((*bufp)[i])
-		if ( ! (*r->msg)(MANDOCERR_ARGSLOST, r->data, ln, i, NULL))
-			return(ROFF_ERR);
+	if (ROFF_ie == tok) {
+		/*
+		 * An if-else will put the NEGATION of the current
+		 * evaluated conditional into the stack.
+		 */
+		r->rstackpos++;
+		if (ROFFRULE_DENY == r->last->rule)
+			r->rstack[r->rstackpos] = ROFFRULE_ALLOW;
+		else
+			r->rstack[r->rstackpos] = ROFFRULE_DENY;
+	}
 
+	/* If the parent has false as its rule, then so do we. */
+
+	if (r->last->parent && ROFFRULE_DENY == r->last->parent->rule) {
+		r->last->rule = ROFFRULE_DENY;
+		ROFF_DEBUG("roff: cond override: %s -> deny\n",
+				roffs[tok].name);
+	}
+
 	/*
-	 * If the macro has arguments, the first argument (up to the
-	 * next whitespace) is interpreted as an argument marking the
-	 * macro close.  Thus, `.ig foo' will close at `.foo'.
-	 *
-	 * NOTE: the closing macro `.foo' in the above case is not
-	 * allowed to have leading spaces with old groff!  Thus `.foo'
-	 * != `. foo'.  Oh yeah, everything after the `.foo' is lost.
-	 * Merry fucking Christmas.
+	 * Determine scope.  If we're invoked with "\{" trailing the
+	 * conditional, then we're in a multiline scope.  Else our scope
+	 * expires on the next line.
 	 */
 
-	r->last->end = malloc((size_t)(i - ppos) + 1);
-	if (NULL == r->last->end) {
-		(*r->msg)(MANDOCERR_MEM, r->data, ln, ppos, NULL);
-		return(ROFF_ERR);
-	}
+	r->last->endspan = 1;
 
-	memcpy(r->last->end, &(*bufp)[ppos], (size_t)(i - ppos));
-	r->last->end[i - ppos] = '\0';
+	if ('\\' == (*bufp)[pos] && '{' == (*bufp)[pos + 1]) {
+		r->last->endspan = -1;
+		pos += 2;
+		ROFF_DEBUG("roff: cond-scope: %s, multi-line\n", 
+				roffs[tok].name);
+	} else
+		ROFF_DEBUG("roff: cond-scope: %s, one-line\n", 
+				roffs[tok].name);
 
+	/*
+	 * If there are no arguments on the line, the next-line scope is
+	 * assumed.
+	 */
+
+	if ('\0' == (*bufp)[pos])
+		return(ROFF_IGN);
+
+	/* Otherwise re-run the roff parser after recalculating. */
+
+	*offs = pos;
+	return(ROFF_RERUN);
+}
+
+
+/* ARGSUSED */
+static enum rofferr
+roff_line(ROFF_ARGS)
+{
+
 	return(ROFF_IGN);
 }
-#endif