Clarified the role of MDOC_HALT in libmdoc functions by having accessor

functions assert() if they're called after MDOC_HALT is set.

This makes more sense than returning 0 because this return value is used
for parse errors, not programme-flow errors, and it's inconsistent to
use the same value for both.  Plus, prior to this, I'd return 0 without
printing an error message, which would cause failure to go unreported to
the operator.

2 files changed, 20 insertions, 21 deletions

diff --git a/mdoc.3 b/mdoc.3
index 358008d8..f5259bac 100644
--- a/mdoc.3
+++ b/mdoc.3
@@ -96,6 +96,16 @@ See
 for details.
 .El
 .Ss Functions
+If
+.Fn mdoc_addspan ,
+.Fn mdoc_parseln ,
+or
+.Fn mdoc_endparse
+return 0, calls to any function but
+.Fn mdoc_reset
+or
+.Fn mdoc_free
+will raise an assertion.
 .Bl -ohang
 .It Fn mdoc_addspan
 Add a table span to the parsing stream.
@@ -106,8 +116,8 @@ The
 .Fa data
 pointer is passed to
 .Fa msgs .
-Returns NULL on failure.
-If non-NULL, the pointer must be freed with
+Always returns a valid pointer.
+The pointer must be freed with
 .Fn mdoc_free .
 .It Fn mdoc_reset
 Reset the parser for another parse routine.
@@ -135,18 +145,8 @@ the resulting tree is incomplete.
 Returns 0 on failure, 1 on success.
 .It Fn mdoc_node
 Returns the first node of the parse.
-Note that if
-.Fn mdoc_parseln
-or
-.Fn mdoc_endparse
-return 0, the tree will be incomplete.
 .It Fn mdoc_meta
 Returns the document's parsed meta-data.
-If this information has not yet been supplied or
-.Fn mdoc_parseln
-or
-.Fn mdoc_endparse
-return 0, the data will be incomplete.
 .El
 .Ss Variables
 .Bl -ohang
diff --git a/mdoc.c b/mdoc.c
index 389f0bc1..5494b633 100644
--- a/mdoc.c
+++ b/mdoc.c
@@ -106,7 +106,8 @@ const struct mdoc_node *
 mdoc_node(const struct mdoc *m)
 {
 
-	return(MDOC_HALT & m->flags ? NULL : m->first);
+	assert( ! (MDOC_HALT & m->flags));
+	return(m->first);
 }
 
 
@@ -114,7 +115,8 @@ const struct mdoc_meta *
 mdoc_meta(const struct mdoc *m)
 {
 
-	return(MDOC_HALT & m->flags ? NULL : &m->meta);
+	assert( ! (MDOC_HALT & m->flags));
+	return(&m->meta);
 }
 
 
@@ -215,9 +217,8 @@ int
 mdoc_endparse(struct mdoc *m)
 {
 
-	if (MDOC_HALT & m->flags)
-		return(0);
-	else if (mdoc_macroend(m))
+	assert( ! (MDOC_HALT & m->flags));
+	if (mdoc_macroend(m))
 		return(1);
 	m->flags |= MDOC_HALT;
 	return(0);
@@ -227,8 +228,7 @@ int
 mdoc_addspan(struct mdoc *m, const struct tbl_span *sp)
 {
 
-	if (MDOC_HALT & m->flags)
-		return(0);
+	assert( ! (MDOC_HALT & m->flags));
 
 	/* No text before an initial macro. */
 
@@ -250,8 +250,7 @@ int
 mdoc_parseln(struct mdoc *m, int ln, char *buf, int offs)
 {
 
-	if (MDOC_HALT & m->flags)
-		return(0);
+	assert( ! (MDOC_HALT & m->flags));
 
 	m->flags |= MDOC_NEWLINE;