===================================================================
RCS file: /cvs/mandoc/eqn.c,v
retrieving revision 1.51
retrieving revision 1.63
diff -u -p -r1.51 -r1.63
--- mandoc/eqn.c	2014/10/10 14:27:46	1.51
+++ mandoc/eqn.c	2017/06/20 17:24:35	1.63
@@ -1,6 +1,7 @@
-/*	$Id: eqn.c,v 1.51 2014/10/10 14:27:46 schwarze Exp $ */
+/*	$Id: eqn.c,v 1.63 2017/06/20 17:24:35 schwarze Exp $ */
 /*
  * Copyright (c) 2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
+ * Copyright (c) 2014, 2015 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
@@ -30,13 +31,9 @@
 #include "libmandoc.h"
 #include "libroff.h"
 
-#define	EQN_MSG(t, x) \
-	mandoc_msg((t), (x)->parse, (x)->eqn.ln, (x)->eqn.pos, NULL)
 #define	EQN_NEST_MAX	 128 /* maximum nesting of defines */
 #define	STRNEQ(p1, sz1, p2, sz2) \
 	((sz1) == (sz2) && 0 == strncmp((p1), (p2), (sz1)))
-#define	EQNSTREQ(x, p, sz) \
-	STRNEQ((x)->name, (x)->sz, (p), (sz))
 
 enum	eqn_tok {
 	EQN_TOK_DYAD = 0,
@@ -197,6 +194,7 @@ enum	eqn_symt {
 	EQNSYM_equiv,
 	EQNSYM_lessequal,
 	EQNSYM_moreequal,
+	EQNSYM_minus,
 	EQNSYM__MAX
 };
 
@@ -252,7 +250,7 @@ static	const struct eqnsym eqnsyms[EQNSYM__MAX] = {
 	{ "cdot", "pc" }, /* EQNSYM_cdot */
 	{ "nothing", "&" }, /* EQNSYM_nothing */
 	{ "approx", "~~" }, /* EQNSYM_approx */
-	{ "prime", "aq" }, /* EQNSYM_prime */
+	{ "prime", "fm" }, /* EQNSYM_prime */
 	{ "half", "12" }, /* EQNSYM_half */
 	{ "partial", "pd" }, /* EQNSYM_partial */
 	{ "inf", "if" }, /* EQNSYM_inf */
@@ -265,8 +263,24 @@ static	const struct eqnsym eqnsyms[EQNSYM__MAX] = {
 	{ "==", "==" }, /* EQNSYM_equiv */
 	{ "<=", "<=" }, /* EQNSYM_lessequal */
 	{ ">=", ">=" }, /* EQNSYM_moreequal */
+	{ "-", "mi" }, /* EQNSYM_minus */
 };
 
+static	struct eqn_box	*eqn_box_alloc(struct eqn_node *, struct eqn_box *);
+static	void		 eqn_box_free(struct eqn_box *);
+static	struct eqn_box	*eqn_box_makebinary(struct eqn_node *,
+				enum eqn_post, struct eqn_box *);
+static	void		 eqn_def(struct eqn_node *);
+static	struct eqn_def	*eqn_def_find(struct eqn_node *, const char *, size_t);
+static	void		 eqn_delim(struct eqn_node *);
+static	const char	*eqn_next(struct eqn_node *, char, size_t *, int);
+static	const char	*eqn_nextrawtok(struct eqn_node *, size_t *);
+static	const char	*eqn_nexttok(struct eqn_node *, size_t *);
+static	enum rofferr	 eqn_parse(struct eqn_node *, struct eqn_box *);
+static	enum eqn_tok	 eqn_tok_parse(struct eqn_node *, char **);
+static	void		 eqn_undef(struct eqn_node *);
+
+
 enum rofferr
 eqn_read(struct eqn_node **epp, int ln,
 		const char *p, int pos, int *offs)
@@ -288,10 +302,10 @@ eqn_read(struct eqn_node **epp, int ln,
 		while (' ' == *p || '\t' == *p)
 			p++;
 		if ('\0' == *p)
-			return(er);
+			return er;
 		mandoc_vmsg(MANDOCERR_ARG_SKIP, ep->parse,
 		    ln, pos, "EN %s", p);
-		return(er);
+		return er;
 	}
 
 	/*
@@ -310,34 +324,22 @@ eqn_read(struct eqn_node **epp, int ln,
 	ep->sz += sz;
 	strlcat(ep->data, p + pos, ep->sz + 1);
 	strlcat(ep->data, " ", ep->sz + 1);
-	return(ROFF_IGN);
+	return ROFF_IGN;
 }
 
 struct eqn_node *
-eqn_alloc(const char *name, int pos, int line, struct mparse *parse)
+eqn_alloc(int pos, int line, struct mparse *parse)
 {
 	struct eqn_node	*p;
-	size_t		 sz;
-	const char	*end;
 
 	p = mandoc_calloc(1, sizeof(struct eqn_node));
 
-	if (name && '\0' != *name) {
-		sz = strlen(name);
-		assert(sz);
-		do {
-			sz--;
-			end = name + (int)sz;
-		} while (' ' == *end || '\t' == *end);
-		p->eqn.name = mandoc_strndup(name, sz + 1);
-	}
-
 	p->parse = parse;
 	p->eqn.ln = line;
 	p->eqn.pos = pos;
 	p->gsize = EQN_DEFSIZE;
 
-	return(p);
+	return p;
 }
 
 /*
@@ -351,9 +353,9 @@ eqn_def_find(struct eqn_node *ep, const char *key, siz
 	for (i = 0; i < (int)ep->defsz; i++)
 		if (ep->defs[i].keysz && STRNEQ(ep->defs[i].key,
 		    ep->defs[i].keysz, key, sz))
-			return(&ep->defs[i]);
+			return &ep->defs[i];
 
-	return(NULL);
+	return NULL;
 }
 
 /*
@@ -364,22 +366,27 @@ eqn_def_find(struct eqn_node *ep, const char *key, siz
 static const char *
 eqn_next(struct eqn_node *ep, char quote, size_t *sz, int repl)
 {
+	static size_t	 last_len;
+	static int	 lim;
+
 	char		*start, *next;
-	int		 q, diff, lim;
+	int		 q, diff;
 	size_t		 ssz, dummy;
 	struct eqn_def	*def;
 
 	if (NULL == sz)
 		sz = &dummy;
 
-	lim = 0;
+	if (ep->cur >= last_len)
+		lim = 0;
 	ep->rew = ep->cur;
 again:
 	/* Prevent self-definitions. */
 
 	if (lim >= EQN_NEST_MAX) {
-		EQN_MSG(MANDOCERR_ROFFLOOP, ep);
-		return(NULL);
+		mandoc_msg(MANDOCERR_ROFFLOOP, ep->parse,
+		    ep->eqn.ln, ep->eqn.pos, NULL);
+		return NULL;
 	}
 
 	ep->cur = ep->rew;
@@ -387,7 +394,7 @@ again:
 	q = 0;
 
 	if ('\0' == *start)
-		return(NULL);
+		return NULL;
 
 	if (quote == *start) {
 		ep->cur++;
@@ -419,7 +426,8 @@ again:
 			ep->cur++;
 	} else {
 		if (q)
-			EQN_MSG(MANDOCERR_ARG_QUOTE, ep);
+			mandoc_msg(MANDOCERR_ARG_QUOTE, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, NULL);
 		next = strchr(start, '\0');
 		*sz = (size_t)(next - start);
 		ep->cur += *sz;
@@ -428,7 +436,7 @@ again:
 	/* Quotes aren't expanded for values. */
 
 	if (q || ! repl)
-		return(start);
+		return start;
 
 	if (NULL != (def = eqn_def_find(ep, start, *sz))) {
 		diff = def->valsz - *sz;
@@ -444,10 +452,12 @@ again:
 		memmove(start + *sz + diff, start + *sz,
 		    (strlen(start) - *sz) + 1);
 		memcpy(start, def->val, def->valsz);
+		last_len = start - ep->data + def->valsz;
+		lim++;
 		goto again;
 	}
 
-	return(start);
+	return start;
 }
 
 /*
@@ -458,7 +468,7 @@ static const char *
 eqn_nexttok(struct eqn_node *ep, size_t *sz)
 {
 
-	return(eqn_next(ep, '"', sz, 1));
+	return eqn_next(ep, '"', sz, 1);
 }
 
 /*
@@ -468,7 +478,7 @@ static const char *
 eqn_nextrawtok(struct eqn_node *ep, size_t *sz)
 {
 
-	return(eqn_next(ep, '"', sz, 0));
+	return eqn_next(ep, '"', sz, 0);
 }
 
 /*
@@ -486,13 +496,22 @@ eqn_tok_parse(struct eqn_node *ep, char **p)
 {
 	const char	*start;
 	size_t		 i, sz;
+	int		 quoted;
 
 	if (NULL != p)
 		*p = NULL;
 
+	quoted = ep->data[ep->cur] == '"';
+
 	if (NULL == (start = eqn_nexttok(ep, &sz)))
-		return(EQN_TOK_EOF);
+		return EQN_TOK_EOF;
 
+	if (quoted) {
+		if (p != NULL)
+			*p = mandoc_strndup(start, sz);
+		return EQN_TOK__MAX;
+	}
+
 	for (i = 0; i < EQN_TOK__MAX; i++) {
 		if (NULL == eqn_toks[i])
 			continue;
@@ -503,7 +522,7 @@ eqn_tok_parse(struct eqn_node *ep, char **p)
 	if (i == EQN_TOK__MAX && NULL != p)
 		*p = mandoc_strndup(start, sz);
 
-	return(i);
+	return i;
 }
 
 static void
@@ -544,7 +563,7 @@ eqn_box_alloc(struct eqn_node *ep, struct eqn_box *par
 		parent->first = bp;
 
 	parent->last = bp;
-	return(bp);
+	return bp;
 }
 
 /*
@@ -574,29 +593,57 @@ eqn_box_makebinary(struct eqn_node *ep,
 	newb->first = newb->last = b;
 	newb->first->next = NULL;
 	b->parent = newb;
-	return(newb);
+	return newb;
 }
 
 /*
+ * Parse the "delim" control statement.
+ */
+static void
+eqn_delim(struct eqn_node *ep)
+{
+	const char	*start;
+	size_t		 sz;
+
+	if ((start = eqn_nextrawtok(ep, &sz)) == NULL)
+		mandoc_msg(MANDOCERR_REQ_EMPTY, ep->parse,
+		    ep->eqn.ln, ep->eqn.pos, "delim");
+	else if (strncmp(start, "off", 3) == 0)
+		ep->delim = 0;
+	else if (strncmp(start, "on", 2) == 0) {
+		if (ep->odelim && ep->cdelim)
+			ep->delim = 1;
+	} else if (start[1] != '\0') {
+		ep->odelim = start[0];
+		ep->cdelim = start[1];
+		ep->delim = 1;
+	}
+}
+
+/*
  * Undefine a previously-defined string.
  */
-static int
+static void
 eqn_undef(struct eqn_node *ep)
 {
 	const char	*start;
 	struct eqn_def	*def;
 	size_t		 sz;
 
-	if (NULL == (start = eqn_nextrawtok(ep, &sz))) {
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-		return(0);
-	} else if (NULL != (def = eqn_def_find(ep, start, sz)))
-		def->keysz = 0;
-
-	return(1);
+	if ((start = eqn_nextrawtok(ep, &sz)) == NULL) {
+		mandoc_msg(MANDOCERR_REQ_EMPTY, ep->parse,
+		    ep->eqn.ln, ep->eqn.pos, "undef");
+		return;
+	}
+	if ((def = eqn_def_find(ep, start, sz)) == NULL)
+		return;
+	free(def->key);
+	free(def->val);
+	def->key = def->val = NULL;
+	def->keysz = def->valsz = 0;
 }
 
-static int
+static void
 eqn_def(struct eqn_node *ep)
 {
 	const char	*start;
@@ -604,9 +651,10 @@ eqn_def(struct eqn_node *ep)
 	struct eqn_def	*def;
 	int		 i;
 
-	if (NULL == (start = eqn_nextrawtok(ep, &sz))) {
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-		return(0);
+	if ((start = eqn_nextrawtok(ep, &sz)) == NULL) {
+		mandoc_msg(MANDOCERR_REQ_EMPTY, ep->parse,
+		    ep->eqn.ln, ep->eqn.pos, "define");
+		return;
 	}
 
 	/*
@@ -626,113 +674,123 @@ eqn_def(struct eqn_node *ep)
 			ep->defs[i].key = ep->defs[i].val = NULL;
 		}
 
-		ep->defs[i].keysz = sz;
-		ep->defs[i].key = mandoc_realloc(
-		    ep->defs[i].key, sz + 1);
-
-		memcpy(ep->defs[i].key, start, sz);
-		ep->defs[i].key[(int)sz] = '\0';
-		def = &ep->defs[i];
+		def = ep->defs + i;
+		free(def->key);
+		def->key = mandoc_strndup(start, sz);
+		def->keysz = sz;
 	}
 
 	start = eqn_next(ep, ep->data[(int)ep->cur], &sz, 0);
-
-	if (NULL == start) {
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-		return(-1);
+	if (start == NULL) {
+		mandoc_vmsg(MANDOCERR_REQ_EMPTY, ep->parse,
+		    ep->eqn.ln, ep->eqn.pos, "define %s", def->key);
+		free(def->key);
+		free(def->val);
+		def->key = def->val = NULL;
+		def->keysz = def->valsz = 0;
+		return;
 	}
-
+	free(def->val);
+	def->val = mandoc_strndup(start, sz);
 	def->valsz = sz;
-	def->val = mandoc_realloc(def->val, sz + 1);
-	memcpy(def->val, start, sz);
-	def->val[(int)sz] = '\0';
-	return(1);
 }
 
 /*
  * Recursively parse an eqn(7) expression.
  */
-static int
+static enum rofferr
 eqn_parse(struct eqn_node *ep, struct eqn_box *parent)
 {
-	char		*p;
-	enum eqn_tok	 tok;
-	enum eqn_post	 pos;
-	struct eqn_box	*cur;
-	int		 rc, size;
-	size_t		 i, sz;
 	char		 sym[64];
+	struct eqn_box	*cur;
 	const char	*start;
+	char		*p;
+	size_t		 i, sz;
+	enum eqn_tok	 tok, subtok;
+	enum eqn_post	 pos;
+	int		 size;
 
-	assert(NULL != parent);
-again:
+	assert(parent != NULL);
 
-	switch ((tok = eqn_tok_parse(ep, &p))) {
-	case (EQN_TOK_UNDEF):
-		if ((rc = eqn_undef(ep)) <= 0)
-			return(rc);
+	/*
+	 * Empty equation.
+	 * Do not add it to the high-level syntax tree.
+	 */
+
+	if (ep->data == NULL)
+		return ROFF_IGN;
+
+next_tok:
+	tok = eqn_tok_parse(ep, &p);
+
+this_tok:
+	switch (tok) {
+	case EQN_TOK_UNDEF:
+		eqn_undef(ep);
 		break;
-	case (EQN_TOK_NDEFINE):
-	case (EQN_TOK_DEFINE):
-		if ((rc = eqn_def(ep)) <= 0)
-			return(rc);
+	case EQN_TOK_NDEFINE:
+	case EQN_TOK_DEFINE:
+		eqn_def(ep);
 		break;
-	case (EQN_TOK_TDEFINE):
-		if (NULL == eqn_nextrawtok(ep, NULL))
-			EQN_MSG(MANDOCERR_EQNEOF, ep);
-		else if (NULL == eqn_next(ep,
-				ep->data[(int)ep->cur], NULL, 0))
-			EQN_MSG(MANDOCERR_EQNEOF, ep);
+	case EQN_TOK_TDEFINE:
+		if (eqn_nextrawtok(ep, NULL) == NULL ||
+		    eqn_next(ep, ep->data[(int)ep->cur], NULL, 0) == NULL)
+			mandoc_msg(MANDOCERR_REQ_EMPTY, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, "tdefine");
 		break;
-	case (EQN_TOK_DELIM):
-	case (EQN_TOK_GFONT):
-		if (NULL == eqn_nextrawtok(ep, NULL)) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(-1);
-		}
+	case EQN_TOK_DELIM:
+		eqn_delim(ep);
 		break;
-	case (EQN_TOK_MARK):
-	case (EQN_TOK_LINEUP):
+	case EQN_TOK_GFONT:
+		if (eqn_nextrawtok(ep, NULL) == NULL)
+			mandoc_msg(MANDOCERR_REQ_EMPTY, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, eqn_toks[tok]);
+		break;
+	case EQN_TOK_MARK:
+	case EQN_TOK_LINEUP:
 		/* Ignore these. */
 		break;
-	case (EQN_TOK_DYAD):
-	case (EQN_TOK_VEC):
-	case (EQN_TOK_UNDER):
-	case (EQN_TOK_BAR):
-	case (EQN_TOK_TILDE):
-	case (EQN_TOK_HAT):
-	case (EQN_TOK_DOT):
-	case (EQN_TOK_DOTDOT):
-		if (NULL == parent->last) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(-1);
+	case EQN_TOK_DYAD:
+	case EQN_TOK_VEC:
+	case EQN_TOK_UNDER:
+	case EQN_TOK_BAR:
+	case EQN_TOK_TILDE:
+	case EQN_TOK_HAT:
+	case EQN_TOK_DOT:
+	case EQN_TOK_DOTDOT:
+		if (parent->last == NULL) {
+			mandoc_msg(MANDOCERR_EQN_NOBOX, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, eqn_toks[tok]);
+			cur = eqn_box_alloc(ep, parent);
+			cur->type = EQN_TEXT;
+			cur->text = mandoc_strdup("");
 		}
 		parent = eqn_box_makebinary(ep, EQNPOS_NONE, parent);
 		parent->type = EQN_LISTONE;
 		parent->expectargs = 1;
 		switch (tok) {
-		case (EQN_TOK_DOTDOT):
+		case EQN_TOK_DOTDOT:
 			strlcpy(sym, "\\[ad]", sizeof(sym));
 			break;
-		case (EQN_TOK_VEC):
+		case EQN_TOK_VEC:
 			strlcpy(sym, "\\[->]", sizeof(sym));
 			break;
-		case (EQN_TOK_DYAD):
+		case EQN_TOK_DYAD:
 			strlcpy(sym, "\\[<>]", sizeof(sym));
 			break;
-		case (EQN_TOK_TILDE):
+		case EQN_TOK_TILDE:
 			strlcpy(sym, "\\[a~]", sizeof(sym));
 			break;
-		case (EQN_TOK_UNDER):
+		case EQN_TOK_UNDER:
 			strlcpy(sym, "\\[ul]", sizeof(sym));
 			break;
-		case (EQN_TOK_BAR):
+		case EQN_TOK_BAR:
 			strlcpy(sym, "\\[rl]", sizeof(sym));
 			break;
-		case (EQN_TOK_DOT):
+		case EQN_TOK_DOT:
 			strlcpy(sym, "\\[a.]", sizeof(sym));
 			break;
-		case (EQN_TOK_HAT):
+		case EQN_TOK_HAT:
 			strlcpy(sym, "\\[ha]", sizeof(sym));
 			break;
 		default:
@@ -740,16 +798,16 @@ again:
 		}
 
 		switch (tok) {
-		case (EQN_TOK_DOTDOT):
-		case (EQN_TOK_VEC):
-		case (EQN_TOK_DYAD):
-		case (EQN_TOK_TILDE):
-		case (EQN_TOK_BAR):
-		case (EQN_TOK_DOT):
-		case (EQN_TOK_HAT):
+		case EQN_TOK_DOTDOT:
+		case EQN_TOK_VEC:
+		case EQN_TOK_DYAD:
+		case EQN_TOK_TILDE:
+		case EQN_TOK_BAR:
+		case EQN_TOK_DOT:
+		case EQN_TOK_HAT:
 			parent->top = mandoc_strdup(sym);
 			break;
-		case (EQN_TOK_UNDER):
+		case EQN_TOK_UNDER:
 			parent->bottom = mandoc_strdup(sym);
 			break;
 		default:
@@ -757,25 +815,24 @@ again:
 		}
 		parent = parent->parent;
 		break;
-	case (EQN_TOK_FWD):
-	case (EQN_TOK_BACK):
-	case (EQN_TOK_DOWN):
-	case (EQN_TOK_UP):
-		tok = eqn_tok_parse(ep, NULL);
-		if (EQN_TOK__MAX != tok) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(-1);
+	case EQN_TOK_FWD:
+	case EQN_TOK_BACK:
+	case EQN_TOK_DOWN:
+	case EQN_TOK_UP:
+		subtok = eqn_tok_parse(ep, NULL);
+		if (subtok != EQN_TOK__MAX) {
+			mandoc_msg(MANDOCERR_REQ_EMPTY, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, eqn_toks[tok]);
+			tok = subtok;
+			goto this_tok;
 		}
 		break;
-	case (EQN_TOK_FAT):
-	case (EQN_TOK_ROMAN):
-	case (EQN_TOK_ITALIC):
-	case (EQN_TOK_BOLD):
+	case EQN_TOK_FAT:
+	case EQN_TOK_ROMAN:
+	case EQN_TOK_ITALIC:
+	case EQN_TOK_BOLD:
 		while (parent->args == parent->expectargs)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
+			parent = parent->parent;
 		/*
 		 * These values apply to the next word or sequence of
 		 * words; thus, we mark that we'll have a child with
@@ -785,33 +842,35 @@ again:
 		parent->type = EQN_LISTONE;
 		parent->expectargs = 1;
 		switch (tok) {
-		case (EQN_TOK_FAT):
+		case EQN_TOK_FAT:
 			parent->font = EQNFONT_FAT;
 			break;
-		case (EQN_TOK_ROMAN):
+		case EQN_TOK_ROMAN:
 			parent->font = EQNFONT_ROMAN;
 			break;
-		case (EQN_TOK_ITALIC):
+		case EQN_TOK_ITALIC:
 			parent->font = EQNFONT_ITALIC;
 			break;
-		case (EQN_TOK_BOLD):
+		case EQN_TOK_BOLD:
 			parent->font = EQNFONT_BOLD;
 			break;
 		default:
 			abort();
 		}
 		break;
-	case (EQN_TOK_SIZE):
-	case (EQN_TOK_GSIZE):
+	case EQN_TOK_SIZE:
+	case EQN_TOK_GSIZE:
 		/* Accept two values: integral size and a single. */
 		if (NULL == (start = eqn_nexttok(ep, &sz))) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(-1);
+			mandoc_msg(MANDOCERR_REQ_EMPTY, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, eqn_toks[tok]);
+			break;
 		}
 		size = mandoc_strntoi(start, sz, 10);
 		if (-1 == size) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(-1);
+			mandoc_msg(MANDOCERR_IT_NONUM, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, eqn_toks[tok]);
+			break;
 		}
 		if (EQN_TOK_GSIZE == tok) {
 			ep->gsize = size;
@@ -822,18 +881,21 @@ again:
 		parent->expectargs = 1;
 		parent->size = size;
 		break;
-	case (EQN_TOK_FROM):
-	case (EQN_TOK_TO):
-	case (EQN_TOK_SUB):
-	case (EQN_TOK_SUP):
+	case EQN_TOK_FROM:
+	case EQN_TOK_TO:
+	case EQN_TOK_SUB:
+	case EQN_TOK_SUP:
 		/*
 		 * We have a left-right-associative expression.
 		 * Repivot under a positional node, open a child scope
 		 * and keep on reading.
 		 */
-		if (NULL == parent->last) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(-1);
+		if (parent->last == NULL) {
+			mandoc_msg(MANDOCERR_EQN_NOBOX, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, eqn_toks[tok]);
+			cur = eqn_box_alloc(ep, parent);
+			cur->type = EQN_TEXT;
+			cur->text = mandoc_strdup("");
 		}
 		/* Handle the "subsup" and "fromto" positions. */
 		if (EQN_TOK_SUP == tok && parent->pos == EQNPOS_SUB) {
@@ -847,16 +909,16 @@ again:
 			break;
 		}
 		switch (tok) {
-		case (EQN_TOK_FROM):
+		case EQN_TOK_FROM:
 			pos = EQNPOS_FROM;
 			break;
-		case (EQN_TOK_TO):
+		case EQN_TOK_TO:
 			pos = EQNPOS_TO;
 			break;
-		case (EQN_TOK_SUP):
+		case EQN_TOK_SUP:
 			pos = EQNPOS_SUP;
 			break;
-		case (EQN_TOK_SUB):
+		case EQN_TOK_SUB:
 			pos = EQNPOS_SUB;
 			break;
 		default:
@@ -864,12 +926,9 @@ again:
 		}
 		parent = eqn_box_makebinary(ep, pos, parent);
 		break;
-	case (EQN_TOK_SQRT):
+	case EQN_TOK_SQRT:
 		while (parent->args == parent->expectargs)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
+			parent = parent->parent;
 		/*
 		 * Accept a left-right-associative set of arguments just
 		 * like sub and sup and friends but without rebalancing
@@ -880,43 +939,47 @@ again:
 		parent->pos = EQNPOS_SQRT;
 		parent->expectargs = 1;
 		break;
-	case (EQN_TOK_OVER):
+	case EQN_TOK_OVER:
 		/*
 		 * We have a right-left-associative fraction.
 		 * Close out anything that's currently open, then
 		 * rebalance and continue reading.
 		 */
-		if (NULL == parent->last) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(-1);
+		if (parent->last == NULL) {
+			mandoc_msg(MANDOCERR_EQN_NOBOX, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, eqn_toks[tok]);
+			cur = eqn_box_alloc(ep, parent);
+			cur->type = EQN_TEXT;
+			cur->text = mandoc_strdup("");
 		}
 		while (EQN_SUBEXPR == parent->type)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
+			parent = parent->parent;
 		parent = eqn_box_makebinary(ep, EQNPOS_OVER, parent);
 		break;
-	case (EQN_TOK_RIGHT):
-	case (EQN_TOK_BRACE_CLOSE):
+	case EQN_TOK_RIGHT:
+	case EQN_TOK_BRACE_CLOSE:
 		/*
 		 * Close out the existing brace.
 		 * FIXME: this is a shitty sentinel: we should really
 		 * have a native EQN_BRACE type or whatnot.
 		 */
-		while (parent->type != EQN_LIST)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
+		for (cur = parent; cur != NULL; cur = cur->parent)
+			if (cur->type == EQN_LIST &&
+			    (tok == EQN_TOK_BRACE_CLOSE ||
+			     cur->left != NULL))
+				break;
+		if (cur == NULL) {
+			mandoc_msg(MANDOCERR_BLK_NOTOPEN, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, eqn_toks[tok]);
+			break;
+		}
+		parent = cur;
 		if (EQN_TOK_RIGHT == tok) {
-			if (NULL == parent->left) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
 			if (NULL == (start = eqn_nexttok(ep, &sz))) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
+				mandoc_msg(MANDOCERR_REQ_EMPTY,
+				    ep->parse, ep->eqn.ln,
+				    ep->eqn.pos, eqn_toks[tok]);
+				break;
 			}
 			/* Handling depends on right/left. */
 			if (STRNEQ(start, sz, "ceiling", 7)) {
@@ -928,42 +991,34 @@ again:
 			} else
 				parent->right = mandoc_strndup(start, sz);
 		}
-		if (NULL == (parent = parent->parent)) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(-1);
-		}
-		if (EQN_TOK_BRACE_CLOSE == tok && parent &&
+		parent = parent->parent;
+		if (tok == EQN_TOK_BRACE_CLOSE &&
 		    (parent->type == EQN_PILE ||
 		     parent->type == EQN_MATRIX))
 			parent = parent->parent;
 		/* Close out any "singleton" lists. */
 		while (parent->type == EQN_LISTONE &&
 		    parent->args == parent->expectargs)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
+			parent = parent->parent;
 		break;
-	case (EQN_TOK_BRACE_OPEN):
-	case (EQN_TOK_LEFT):
+	case EQN_TOK_BRACE_OPEN:
+	case EQN_TOK_LEFT:
 		/*
 		 * If we already have something in the stack and we're
 		 * in an expression, then rewind til we're not any more
 		 * (just like with the text node).
 		 */
 		while (parent->args == parent->expectargs)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
+			parent = parent->parent;
+		if (EQN_TOK_LEFT == tok &&
+		    (start = eqn_nexttok(ep, &sz)) == NULL) {
+			mandoc_msg(MANDOCERR_REQ_EMPTY, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, eqn_toks[tok]);
+			break;
+		}
 		parent = eqn_box_alloc(ep, parent);
 		parent->type = EQN_LIST;
 		if (EQN_TOK_LEFT == tok) {
-			if (NULL == (start = eqn_nexttok(ep, &sz))) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
-			/* Handling depends on right/left. */
 			if (STRNEQ(start, sz, "ceiling", 7)) {
 				strlcpy(sym, "\\[lc]", sizeof(sym));
 				parent->left = mandoc_strdup(sym);
@@ -974,57 +1029,44 @@ again:
 				parent->left = mandoc_strndup(start, sz);
 		}
 		break;
-	case (EQN_TOK_PILE):
-	case (EQN_TOK_LPILE):
-	case (EQN_TOK_RPILE):
-	case (EQN_TOK_CPILE):
-	case (EQN_TOK_CCOL):
-	case (EQN_TOK_LCOL):
-	case (EQN_TOK_RCOL):
+	case EQN_TOK_PILE:
+	case EQN_TOK_LPILE:
+	case EQN_TOK_RPILE:
+	case EQN_TOK_CPILE:
+	case EQN_TOK_CCOL:
+	case EQN_TOK_LCOL:
+	case EQN_TOK_RCOL:
 		while (parent->args == parent->expectargs)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
-		if (EQN_TOK_BRACE_OPEN != eqn_tok_parse(ep, NULL)) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(-1);
-		}
+			parent = parent->parent;
 		parent = eqn_box_alloc(ep, parent);
 		parent->type = EQN_PILE;
-		parent = eqn_box_alloc(ep, parent);
-		parent->type = EQN_LIST;
+		parent->expectargs = 1;
 		break;
-	case (EQN_TOK_ABOVE):
-		while (parent->type != EQN_PILE)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
-		parent = eqn_box_alloc(ep, parent);
+	case EQN_TOK_ABOVE:
+		for (cur = parent; cur != NULL; cur = cur->parent)
+			if (cur->type == EQN_PILE)
+				break;
+		if (cur == NULL) {
+			mandoc_msg(MANDOCERR_IT_STRAY, ep->parse,
+			    ep->eqn.ln, ep->eqn.pos, eqn_toks[tok]);
+			break;
+		}
+		parent = eqn_box_alloc(ep, cur);
 		parent->type = EQN_LIST;
 		break;
-	case (EQN_TOK_MATRIX):
+	case EQN_TOK_MATRIX:
 		while (parent->args == parent->expectargs)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
-		if (EQN_TOK_BRACE_OPEN != eqn_tok_parse(ep, NULL)) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(-1);
-		}
+			parent = parent->parent;
 		parent = eqn_box_alloc(ep, parent);
 		parent->type = EQN_MATRIX;
-		parent = eqn_box_alloc(ep, parent);
-		parent->type = EQN_LIST;
+		parent->expectargs = 1;
 		break;
-	case (EQN_TOK_EOF):
+	case EQN_TOK_EOF:
 		/*
 		 * End of file!
 		 * TODO: make sure we're not in an open subexpression.
 		 */
-		return(0);
+		return ROFF_EQN;
 	default:
 		assert(tok == EQN_TOK__MAX);
 		assert(NULL != p);
@@ -1033,11 +1075,7 @@ again:
 		 * in an expression, then rewind til we're not any more.
 		 */
 		while (parent->args == parent->expectargs)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				free(p);
-				return(-1);
-			}
+			parent = parent->parent;
 		cur = eqn_box_alloc(ep, parent);
 		cur->type = EQN_TEXT;
 		for (i = 0; i < EQNSYM__MAX; i++)
@@ -1055,14 +1093,11 @@ again:
 		 * Post-process list status.
 		 */
 		while (parent->type == EQN_LISTONE &&
-			parent->args == parent->expectargs)
-			if (NULL == (parent = parent->parent)) {
-				EQN_MSG(MANDOCERR_EQNSYNT, ep);
-				return(-1);
-			}
+		    parent->args == parent->expectargs)
+			parent = parent->parent;
 		break;
 	}
-	goto again;
+	goto next_tok;
 }
 
 enum rofferr
@@ -1075,7 +1110,7 @@ eqn_end(struct eqn_node **epp)
 
 	ep->eqn.root = mandoc_calloc(1, sizeof(struct eqn_box));
 	ep->eqn.root->expectargs = UINT_MAX;
-	return(0 == eqn_parse(ep, ep->eqn.root) ? ROFF_EQN : ROFF_IGN);
+	return eqn_parse(ep, ep->eqn.root);
 }
 
 void
@@ -1090,7 +1125,6 @@ eqn_free(struct eqn_node *p)
 		free(p->defs[i].val);
 	}
 
-	free(p->eqn.name);
 	free(p->data);
 	free(p->defs);
 	free(p);