Implement in-line equations, much needed by Xenocara manuals.

Put the steering into the roff parser rather than into the mdoc
parser such that it works for all macro languages and on both text
and macro lines.
Line breaks and blank characters generated before and after in-line
equations are not perfect yet, but let's do one thing at a time.

1 files changed, 58 insertions, 11 deletions

diff --git a/roff.c b/roff.c
index 4e5d5024..4bbb48e3 100644
--- a/roff.c
+++ b/roff.c
@@ -120,6 +120,7 @@ struct	roff {
 	struct eqn_node	*last_eqn; /* last equation parsed */
 	struct eqn_node	*first_eqn; /* first equation parsed */
 	struct eqn_node	*eqn; /* current equation being parsed */
+	int		 eqn_inline; /* current equation is inline */
 	int		 options; /* parse options */
 	int		 rstacksz; /* current size limit of rstack */
 	int		 rstackpos; /* position in rstack */
@@ -183,6 +184,8 @@ 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 rofferr	 roff_ds(ROFF_ARGS);
+static	enum rofferr	 roff_eqndelim(struct roff *,
+				char **, size_t *, int);
 static	int		 roff_evalcond(const char *, int *);
 static	int		 roff_evalnum(const char *, int *, int *, int);
 static	int		 roff_evalpar(const char *, int *, int *);
@@ -724,10 +727,17 @@ roff_parseln(struct roff *r, int ln, char **bufp,
 	enum rofferr	 e;
 	int		 ppos, ctl;
 
-	/*
-	 * Run the reserved-word filter only if we have some reserved
-	 * words to fill in.
-	 */
+	/* Handle in-line equation delimiters. */
+
+	if (r->last_eqn != NULL && r->last_eqn->delim &&
+	    (r->eqn == NULL || r->eqn_inline)) {
+		e = roff_eqndelim(r, bufp, szp, pos);
+		if (e == ROFF_REPARSE)
+			return(e);
+		assert(e == ROFF_CONT);
+	}
+
+	/* Expand some escape sequences. */
 
 	e = roff_res(r, bufp, szp, ln, pos);
 	if (ROFF_IGN == e)
@@ -1841,14 +1851,48 @@ roff_T_(ROFF_ARGS)
 	return(ROFF_IGN);
 }
 
-#if 0
-static int
-roff_closeeqn(struct roff *r)
+/*
+ * Handle in-line equation delimiters.
+ */
+static enum rofferr
+roff_eqndelim(struct roff *r, char **bufp, size_t *szp, int pos)
 {
+	char	*cp1, *cp2;
 
-	return(r->eqn && ROFF_EQN == eqn_end(&r->eqn) ? 1 : 0);
+	/*
+	 * Outside equations, look for an opening delimiter.
+	 * If we are inside an equation, we already know it is
+	 * in-line, or this function wouldn't have been called;
+	 * so look for a closing delimiter.
+	 */
+
+	cp1 = *bufp + pos;
+	cp2 = strchr(cp1, r->eqn == NULL ?
+	    r->last_eqn->odelim : r->last_eqn->cdelim);
+	if (cp2 == NULL)
+		return(ROFF_CONT);
+
+	/* Found a delimiter; get rid of surrounding blanks. */
+
+	cp1 = cp2++;
+	while (cp2[0] == ' ')
+		cp2++;
+	while (cp1[-1] == ' ')
+		cp1--;
+	*cp1 = '\0';
+
+	/* Replace the delimiter with an equation macro. */
+
+	*szp = mandoc_asprintf(&cp1, "%s\n.E%c\n\\&%s", *bufp,
+	    r->eqn == NULL ? 'Q' : 'N', cp2) + 1;
+	free(*bufp);
+	*bufp = cp1;
+
+	/* Toggle the in-line state of the eqn subsystem. */
+
+	r->eqn_inline = r->eqn == NULL;
+	return(ROFF_REPARSE);
 }
-#endif
 
 static void
 roff_openeqn(struct roff *r, const char *name, int line,
@@ -1860,9 +1904,12 @@ roff_openeqn(struct roff *r, const char *name, int line,
 	assert(NULL == r->eqn);
 	e = eqn_alloc(name, offs, line, r->parse);
 
-	if (r->last_eqn)
+	if (r->last_eqn) {
 		r->last_eqn->next = e;
-	else
+		e->delim = r->last_eqn->delim;
+		e->odelim = r->last_eqn->odelim;
+		e->cdelim = r->last_eqn->cdelim;
+	} else
 		r->first_eqn = r->last_eqn = e;
 
 	r->eqn = r->last_eqn = e;