Revert "Use char instead of int for FSA rule input"

This reverts commit eb22abfb1b.

lib/include/fsa.h

@@ -8,9 +8,14 @@
 
 #include <stdbool.h>
 
+#define CHAR_COUNT 256
+#define ALPHABET_SIZE (CHAR_COUNT + 1)
+
+// Use one more than any valid char to represent empty string
+#define EPSILON CHAR_COUNT
+
 typedef struct {
-	int next;
-	char input;
+	int input, next;
 } fsa_rule_t;
 
 typedef struct {
@@ -28,6 +33,6 @@ void fsa_init(fsa_t *fsa);
 void fsa_free(const fsa_t *fsa);
 
 int fsa_add_state(fsa_t *fsa);
-void fsa_add_rule(fsa_t *fsa, int from, int to, char input);
+void fsa_add_rule(fsa_t *fsa, int from, int to, int input);
 
 #endif