regex error reporting

1 files changed, 27 insertions, 4 deletions

diff --git a/regex.c b/regex.c
index 6a362e4..88f926e 100644
--- a/regex.c
+++ b/regex.c
@@ -33,6 +33,7 @@ typedef struct {
 	Arena *perm, *scratch;
 	DYNARR(u32) lbl;
 	ReCompFlags flags;
+	ReCompErr err;
 	Str s;
 	int i;
 } ReParser;
@@ -90,7 +91,10 @@ ReNode *re_parse_group(ReParser *s) {
 	/* TODO */
 	skip(s, 1);
 	ReNode *n = re_new_node(s, N_GROUP, re_parse_expr(s), NULL);
-	if (ch(s) != ')') FAIL_WITH_MSG("expected )");
+	if (ch(s) != ')') {
+		s->err = RE_COMP_ENORPAREN;
+		return NULL;
+	}
 	skip(s, 1);
 	return n;
 }
@@ -177,7 +181,7 @@ ReNode *re_parse_atom(ReParser *s) {
 	} break;
 	case 0:
 		/* should never happen? */
-		FAIL_WITH_MSG("atom parsed at end");
+		s->err = RE_COMP_EEOF;
 		return NULL;
 	default: {
 		ReNode *n = re_new_node_char(s, ch(s));
@@ -586,14 +590,33 @@ int re_comp_ex(RegEx *re, Str src, Arena *perm, Arena *scratch, ReCompFlags flag
 		.perm = perm,
 		.scratch = scratch,
 		.s = src,
-		.flags = flags
+		.flags = flags,
+		.err = RE_COMP_ENONE
 	};
 	ReNode *n = re_parse_expr(&s);
+	if (!s.err) {
+		if (s.s.n > 0 && s.s.s[s.s.n - 1] == ')') {
+			s.err = RE_COMP_ENOLPAREN;
+		}
+	}
 
 	if (re_comp_node(&s, n)) return -1;
 	if (re_comp_fin(&s)) return -1;
 
-	return 0;
+	return s.err;
+}
+
+const char *re_comp_strerror(ReCompErr err) {
+	switch (err) {
+	case RE_COMP_ENONE:
+		return "success";
+	case RE_COMP_ENORPAREN:
+		return "no closing )";
+	case RE_COMP_ENOLPAREN:
+		return "no opening (";
+	case RE_COMP_EEOF:
+		return "unexpected end of pattern";
+	}
 }
 
 int re_comp(RegEx *re, Str src, Arena *perm, Arena *scratch) {